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• Java: Preventing array going out of bounds.

  - by Troy

  I'm working on a game of checkers, if you want to read more about you can view it here; http://minnie.tuhs.org/I2P/Assessment/assig2.html When I am doing my test to see if the player is able to get to a certain square on the grid (i.e. +1 +1, +1 -1 .etc) from it's current location, I get an java.lang.ArrayIndexOutOfBoundsException error. This is the code I am using to make the move; public static String makeMove(String move, int playerNumber) { // variables to contain the starting and destination coordinates, subtracting 1 to match array size int colStart = move.charAt(1) - FIRSTCOLREF - 1; int rowStart = move.charAt(0) - FIRSTROWREF - 1; int colEnd = move.charAt(4) - FIRSTCOLREF - 1; int rowEnd = move.charAt(3) - FIRSTROWREF - 1; // variable to contain which player is which char player, enemy; if (playerNumber==1) { player= WHITEPIECE; enemy= BLACKPIECE; } else { player= BLACKPIECE; enemy= WHITEPIECE; } // check that the starting square contains a player piece if (grid [ colStart ] [ rowStart ] == player) { // check that the player is making a diagonal move if (grid [ colEnd ] [ rowEnd ] == grid [ (colStart++) ] [ (rowEnd++) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart--) ] [ (rowEnd++) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart++) ] [ (rowEnd--) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart--) ] [ (rowEnd--) ]) { // check that the destination square is free if (grid [ colEnd ] [ rowEnd ] == BLANK) { grid [ colStart ] [ rowStart ] = BLANK; grid [ colEnd ] [ rowEnd ] = player; } } // check if player is jumping over a piece else if (grid [ colEnd ] [ rowEnd ] == grid [ (colStart+2) ] [ (rowEnd+2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart-2) ] [ (rowEnd+2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart+2) ] [ (rowEnd-2) ] && grid [ colEnd ] [ rowEnd ] == grid [ (colStart-2) ] [ (rowEnd-2) ]) { // check that the piece in between contains an enemy if ((grid [ (colStart++) ] [ (rowEnd++) ] == enemy ) && (grid [ (colStart--) ] [ (rowEnd++) ] == enemy ) && (grid [ (colStart++) ] [ (rowEnd--) ] == enemy ) && (grid [ (colStart--) ] [ (rowEnd--) ] == enemy )) { // check that the destination is free if (grid [ colEnd ] [ rowEnd ] == BLANK) { grid [ colStart ] [ rowStart ] = BLANK; grid [ colEnd ] [ rowEnd ] = player; } } } } I'm not sure how I can prevent the error from happening, what do you recommend?

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• Java Best Practice for type resolution at runtime.

  - by Brian

  I'm trying to define a class (or set of classes which implement the same interface) that will behave as a loosely typed object (like JavaScript). They can hold any sort of data and operations on them depend on the underlying type. I have it working in three different ways but none seem ideal. These test versions only allow strings and integers and the only operation is add. Adding integers results in the sum of the integer values, adding strings concatenates the strings and adding an integer to a string converts the integer to a string and concatenates it with the string. The final version will have more types (Doubles, Arrays, JavaScript-like objects where new properties can be added dynamically) and more operations. Way 1: public interface DynObject1 { @Override public String toString(); public DynObject1 add(DynObject1 d); public DynObject1 addTo(DynInteger1 d); public DynObject1 addTo(DynString1 d); } public class DynInteger1 implements DynObject1 { private int value; public DynInteger1(int v) { value = v; } @Override public String toString() { return Integer.toString(value); } public DynObject1 add(DynObject1 d) { return d.addTo(this); } public DynObject1 addTo(DynInteger1 d) { return new DynInteger1(d.value + value); } public DynObject1 addTo(DynString1 d) { return new DynString1(d.toString()+Integer.toString(value)); } } ...and similar for DynString1 Way 2: public interface DynObject2 { @Override public String toString(); public DynObject2 add(DynObject2 d); } public class DynInteger2 implements DynObject2 { private int value; public DynInteger2(int v) { value = v; } @Override public String toString() { return Integer.toString(value); } public DynObject2 add(DynObject2 d) { Class c = d.getClass(); if(c==DynInteger2.class) { return new DynInteger2(value + ((DynInteger2)d).value); } else { return new DynString2(toString() + d.toString()); } } } ...and similar for DynString2 Way 3: public class DynObject3 { private enum ObjectType { Integer, String }; Object value; ObjectType type; public DynObject3(Integer v) { value = v; type = ObjectType.Integer; } public DynObject3(String v) { value = v; type = ObjectType.String; } @Override public String toString() { return value.toString(); } public DynObject3 add(DynObject3 d) { if(type==ObjectType.Integer && d.type==ObjectType.Integer) { return new DynObject3(Integer.valueOf(((Integer)value).intValue()+((Integer)value).intValue())); } else { return new DynObject3(value.toString()+d.value.toString()); } } } With the if-else logic I could use value.getClass()==Integer.class instead of storing the type but with more types I'd change this to use a switch statement and Java doesn't allow switch to use Classes. Anyway... My question is what is the best way to go about something thike this?

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• Write PEM encoded certificate in file - java

  - by user1349407

  Good day. I recently create X.509 certificate by using bouncy castle API. I need to save the certificate result rather than display the result. I tried to use FileOutputStream, but it does not work. regards the result is like follows -----BEGIN CERTIFICATE----- MIICeTCCAeKgAwIBAgIGATs8OWsXMA0GCSqGSIb3DQEBCwUAMBsxGTAXBgNVBAMT... -----END CERTIFICATE----- The code is belows import java.io.FileOutputStream; //example of a basic CA public class PKCS10CertCreateExample { public static X509Certificate[] buildChain() throws Exception { //create the certification request KeyPair pair = chapter7.Utils.generateRSAKeyPair(); PKCS10CertificationRequest request = PKCS10ExtensionExample.generateRequest(pair); //create a root certificate KeyPair rootPair=chapter7.Utils.generateRSAKeyPair(); X509Certificate rootCert = X509V1CreateExample.generateV1Certificate (rootPair); //validate the certification request if(!request.verify("BC")) { System.out.println("request failed to verify!"); System.exit(1); } //create the certificate using the information in the request X509V3CertificateGenerator certGen = new X509V3CertificateGenerator(); certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis())); certGen.setIssuerDN(rootCert.getSubjectX500Principal()); certGen.setNotBefore(new Date(System.currentTimeMillis())); certGen.setNotAfter(new Date(System.currentTimeMillis()+50000)); certGen.setSubjectDN(request.getCertificationRequestInfo().getSubject()); certGen.setPublicKey(request.getPublicKey("BC")); certGen.setSignatureAlgorithm("SHA256WithRSAEncryption"); certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, false, new AuthorityKeyIdentifierStructure(rootCert)); certGen.addExtension(X509Extensions.SubjectKeyIdentifier, false, new SubjectKeyIdentifierStructure(request.getPublicKey("BC"))); certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false)); //certGen.addExtension(X509Extensions.KeyUsage, true, new BasicConstraints(false)); certGen.addExtension(X509Extensions.KeyUsage, true, new KeyUsage(KeyUsage.digitalSignature | KeyUsage.keyEncipherment)); certGen.addExtension(X509Extensions.ExtendedKeyUsage, true, new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth)); //extract the extension request attribute ASN1Set attributes = request.getCertificationRequestInfo().getAttributes(); for(int i=0;i!=attributes.size();i++) { Attribute attr = Attribute.getInstance(attributes.getObjectAt(i)); //process extension request if(attr.getAttrType().equals(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest)) { X509Extensions extensions = X509Extensions.getInstance(attr.getAttrValues().getObjectAt(0)); Enumeration<?> e = extensions.oids(); while(e.hasMoreElements()) { DERObjectIdentifier oid = (DERObjectIdentifier)e.nextElement(); X509Extension ext = extensions.getExtension(oid); certGen.addExtension(oid, ext.isCritical(), ext.getValue().getOctets()); } } } X509Certificate issuedCert = certGen.generateX509Certificate(rootPair.getPrivate()); return new X509Certificate[]{issuedCert, rootCert}; } public static void main(String[] args) throws Exception { X509Certificate[] chain = buildChain(); PEMWriter pemWrt = new PEMWriter(new OutputStreamWriter(System.out)); pemWrt.writeObject(chain[0]); //pemWrt.writeObject(chain[1]); pemWrt.close(); //write it out //FileOutputStream fOut = new FileOutputStream("pkcs10req.req"); //fOut.write(chain[0].toString()); //fOut.write() //System.out.println(chain[0].toString()); //fOut.close(); } }

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• Java - is this an idiom or pattern, behavior classes with no state

  - by Berlin Brown

  I am trying to incorporate more functional programming idioms into my java development. One pattern that I like the most and avoids side effects is building classes that have behavior but they don't necessarily have any state. The behavior is locked into the methods but they only act on the parameters passed in. The code below is code I am trying to avoid: public class BadObject { private Map<String, String> data = new HashMap<String, String>(); public BadObject() { data.put("data", "data"); } /** * Act on the data class. But this is bad because we can't * rely on the integrity of the object's state. */ public void execute() { data.get("data").toString(); } } The code below is nothing special but I am acting on the parameters and state is contained within that class. We still may run into issues with this class but that is an issue with the method and the state of the data, we can address issues in the routine as opposed to not trusting the entire object. Is this some form of idiom? Is this similar to any pattern that you use? public class SemiStatefulOOP { /** * Private class implies that I can access the members of the <code>Data</code> class * within the <code>SemiStatefulOOP</code> class and I can also access * the getData method from some other class. * * @see Test1 * */ class Data { protected int counter = 0; public int getData() { return counter; } public String toString() { return Integer.toString(counter); } } /** * Act on the data class. */ public void execute(final Data data) { data.counter++; } /** * Act on the data class. */ public void updateStateWithCallToService(final Data data) { data.counter++; } /** * Similar to CLOS (Common Lisp Object System) make instance. */ public Data makeInstance() { return new Data(); } } // End of Class // Issues with the code above: I wanted to declare the Data class private, but then I can't really reference it outside of the class: I can't override the SemiStateful class and access the private members. Usage: final SemiStatefulOOP someObject = new SemiStatefulOOP(); final SemiStatefulOOP.Data data = someObject.makeInstance(); someObject.execute(data); someObject.updateStateWithCallToService(data);

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• Linked lists in Java - help with assignment

  - by user368241

  Representation of a string in linked lists In every intersection in the list there will be 3 fields : The letter itself. The number of times it appears consecutively. A pointer to the next intersection in the list. The following class CharNode represents a intersection in the list : public class CharNode { private char _data; private int _value; private charNode _next; public CharNode (char c, int val, charNode n) { _data = c; _value = val; _next = n; } public charNode getNext() { return _next; } public void setNext (charNode node) { _next = node; } public int getValue() { return _value; } public void setValue (int v) { value = v; } public char getData() { return _data; } public void setData (char c) { _data = c; } } The class StringList represents the whole list : public class StringList { private charNode _head; public StringList() { _head = null; } public StringList (CharNode node) { _head = node; } } Add methods to the class StringList according to the details : (I will add methods gradually according to my specific questions) (Pay attention, these are methods from the class String and we want to fulfill them by the representation of a string by a list as explained above) public int indexOf (int ch) - returns the index in the string it is operated on of the first appeareance of the char "ch". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex isn't in the range, returns -1. Pay attention to all the possible error cases. Write what is the time complexity and space complexity of every method that you wrote. Make sure the methods you wrote are effective. It is NOT allowed to use ready classes of Java. It is NOT allowed to move to string and use string operations. Here is my try to write the method indexOf (int ch). Kindly assist me with fixing the bugs so I can move on. public int indexOf (int ch) { int count = 0; charNode pose = _head; if (pose == null ) { return -1; } for (pose = _head; pose!=null && pose.getNext()!='ch'; pose = pose.getNext()) { count++; } if (pose!=null) return count; else return -1; }

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• run shell command from java

  - by Aykut

  Hi, I am working on an application an have an issue about running shell command from java application. here is the code: public String execRuntime(String cmd) { Process proc = null; int inBuffer, errBuffer; int result = 0; StringBuffer outputReport = new StringBuffer(); StringBuffer errorBuffer = new StringBuffer(); try { proc = Runtime.getRuntime().exec(cmd); } catch (IOException e) { return ""; } try { response.status = 1; result = proc.waitFor(); } catch (InterruptedException e) { return ""; } if (proc != null && null != proc.getInputStream()) { InputStream is = proc.getInputStream(); InputStream es = proc.getErrorStream(); OutputStream os = proc.getOutputStream(); try { while ((inBuffer = is.read()) != -1) { outputReport.append((char) inBuffer); } while ((errBuffer = es.read()) != -1) { errorBuffer.append((char) errBuffer); } } catch (IOException e) { return ""; } try { is.close(); is = null; es.close(); es = null; os.close(); os = null; } catch (IOException e) { return ""; } proc.destroy(); proc = null; } if (errorBuffer.length() > 0) { logger .error("could not finish execution because of error(s)."); logger.error("*** Error : " + errorBuffer.toString()); return ""; } return outputReport.toString(); } but when i try to exec command like : /export/home/test/myapp -T "some argument" myapp reads "some argument" as two seperated arguments.but I want to read "some argument" as only a argument. when i directly run this command from terminal, it executed successfully. I tried '"some argument"' ,""some argument"" , "some\ argument" but did not work for me. how can i read this argument as one argument. Thnaks.

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• Java: Multithreading & UDP Socket Programming

  - by Ravi

  I am new to multithreading & socket programming in Java. I would like to know what is the best way to implement 2 threads - one for receiving a socket and one for sending a socket. If what I am trying to do sounds absurd, pls let me know why! The code is largely inspired from Sun's tutorials online.I want to use Multicast sockets so that I can work with a multicast group. class server extends Thread { static protected MulticastSocket socket = null; protected BufferedReader in = null; public InetAddress group; private static class receive implements Runnable { public void run() { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); socket.receive(pkt); String received = new String(pkt.getData(),0,pkt.getLength()); System.out.println("From server@" + received); Thread.sleep(1000); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } } public server() throws IOException { super("server"); socket = new MulticastSocket(4446); group = InetAddress.getByName("239.231.12.3"); socket.joinGroup(group); } public void run() { while(1>0) { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); //String msg = reader.readLine(); String pid = ManagementFactory.getRuntimeMXBean().getName(); buf = pid.getBytes(); pkt = new DatagramPacket(buf,buf.length,group,4446); socket.send(pkt); Thread t = new Thread(new receive()); t.start(); while(t.isAlive()) { t.join(1000); } sleep(1); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } //socket.close(); } public static void main(String[] args) throws IOException { new server().start(); //System.out.println("Hello"); } }

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• Graph Tour with Uniform Cost Search in Java

  - by user324817

  Hi. I'm new to this site, so hopefully you guys don't mind helping a nub. Anyway, I've been asked to write code to find the shortest cost of a graph tour on a particular graph, whose details are read in from file. The graph is shown below: http://img339.imageshack.us/img339/8907/graphr.jpg This is for an Artificial Intelligence class, so I'm expected to use a decent enough search method (brute force has been allowed, but not for full marks). I've been reading, and I think that what I'm looking for is an A* search with constant heuristic value, which I believe is a uniform cost search. I'm having trouble wrapping my head around how to apply this in Java. Basically, here's what I have: Vertex class - ArrayList<Edge> adjacencies; String name; int costToThis; Edge class - final Vertex target; public final int weight; Now at the moment, I'm struggling to work out how to apply the uniform cost notion to my desired goal path. Basically I have to start on a particular node, visit all other nodes, and end on that same node, with the lowest cost. As I understand it, I could use a PriorityQueue to store all of my travelled paths, but I can't wrap my head around how I show the goal state as the starting node with all other nodes visited. Here's what I have so far, which is pretty far off the mark: public static void visitNode(Vertex vertex) { ArrayList<Edge> firstEdges = vertex.getAdjacencies(); for(Edge e : firstEdges) { e.target.costToThis = e.weight + vertex.costToThis; queue.add(e.target); } Vertex next = queue.remove(); visitNode(next); } Initially this takes the starting node, then recursively visits the first node in the PriorityQueue (the path with the next lowest cost). My problem is basically, how do I stop my program from following a path specified in the queue if that path is at the goal state? The queue currently stores Vertex objects, but in my mind this isn't going to work as I can't store whether other vertices have been visited inside a Vertex object. Help is much appreciated! Josh

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• synchronized in java - Proper use

  - by ZoharYosef

  I'm building a simple program to use in multi processes (Threads). My question is more to understand - when I have to use a reserved word synchronized? Do I need to use this word in any method that affects the bone variables? I know I can put it on any method that is not static, but I want to understand more. thank you! here is the code: public class Container { // *** data members *** public static final int INIT_SIZE=10; // the first (init) size of the set. public static final int RESCALE=10; // the re-scale factor of this set. private int _sp=0; public Object[] _data; /************ Constructors ************/ public Container(){ _sp=0; _data = new Object[INIT_SIZE]; } public Container(Container other) { // copy constructor this(); for(int i=0;i<other.size();i++) this.add(other.at(i)); } /** return true is this collection is empty, else return false. */ public synchronized boolean isEmpty() {return _sp==0;} /** add an Object to this set */ public synchronized void add (Object p){ if (_sp==_data.length) rescale(RESCALE); _data[_sp] = p; // shellow copy semantic. _sp++; } /** returns the actual amount of Objects contained in this collection */ public synchronized int size() {return _sp;} /** returns true if this container contains an element which is equals to ob */ public synchronized boolean isMember(Object ob) { return get(ob)!=-1; } /** return the index of the first object which equals ob, if none returns -1 */ public synchronized int get(Object ob) { int ans=-1; for(int i=0;i<size();i=i+1) if(at(i).equals(ob)) return i; return ans; } /** returns the element located at the ind place in this container (null if out of range) */ public synchronized Object at(int p){ if (p>=0 && p<size()) return _data[p]; else return null; }

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• Java Scanner class reading strings

  - by Max

  I've created a scanner class to read through the text file and get the value what I'm after. Let's assume that I have a text file contains 1 : Fnjiei : ID 7868860 : Age 18 2 : Oipuiieerb : ID 334134 : Age 39 3 : Enekaree : ID 6106274 : Age 31 I'm trying to get a name and id number and age, but everytime I try to run my code it gives me an exception. Here's my code. Any suggestion from java gurus?:) public void readFile(String fileName)throws IOException{ Scanner input = null; input = new Scanner(new BufferedReader(new FileReader(fileName))); try { while (input.hasNextLine()){ int howMany = 3; System.out.println(howMany); String userInput = input.nextLine(); String name = ""; String idS = ""; String ageS = ""; int id; int age; int count=0; for (int j = 0; j <= howMany; j++){ for (int i=0; i < userInput.length(); i++){ if(count < 2){ // for name if(Character.isLetter(userInput.charAt(i))){ name+=userInput.charAt(i); // store the name }else if(userInput.charAt(i)==':'){ count++; i++; } }else if(count == 2){ // for id if(Character.isDigit(userInput.charAt(i))){ idS+=userInput.charAt(i); // store the id } else if(userInput.charAt(i)==':'){ count++; i++; } }else if(count == 3){ // for age if(Character.isDigit(userInput.charAt(i))){ ageS+=userInput.charAt(i); // store the age } } id = Integer.parseInt(idS); // convert id to integer age = Integer.parseInt(ageS); // convert age to integer Fighters newFighters = new Fighters(id, name, age); fighterList.add(newFighters); } userInput = input.nextLine(); } } }finally{ if (input != null){ input.close(); } } } My appology if my mere code begs to be changed.

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• refactoring this function in Java

  - by Joel

  Hi folks, I'm learning Java, and I know one of the big complaints about newbie programmers is that we make really long and involved methods that should be broken into several. Well here is one I wrote and is a perfect example. :-D. public void buildBall(){ /* sets the x and y value for the center of the canvas */ double i = ((getWidth() / 2)); double j = ((getHeight() / 2)); /* randomizes the start speed of the ball */ vy = 3.0; vx = rgen.nextDouble(1.0, 3.0); if (rgen.nextBoolean(.05)) vx = -vx; /* creates the ball */ GOval ball = new GOval(i,j,(2 *BALL_RADIUS),(2 * BALL_RADIUS)); ball.setFilled(true); ball.setFillColor(Color.RED); add(ball); /* animates the ball */ while(true){ i = (i + (vx* 2)); j = (j + (vy* 2)); if (i > APPLICATION_WIDTH-(2 * BALL_RADIUS)){ vx = -vx; } if (j > APPLICATION_HEIGHT-(2 * BALL_RADIUS)){ vy = -vy; } if (i < 0){ vx = -vx; } if (j < 0){ vy = -vy; } ball.move(vx + vx, vy + vy); pause(10); /* checks the edges of the ball to see if it hits an object */ colider = getElementAt(i, j); if (colider == null){ colider = getElementAt(i + (2*BALL_RADIUS), j); } if (colider == null){ colider = getElementAt(i + (2*BALL_RADIUS), j + (2*BALL_RADIUS)); } if (colider == null){ colider = getElementAt(i, j + (2*BALL_RADIUS)); } /* If the ball hits an object it reverses direction */ if (colider != null){ vy = -vy; /* removes bricks when hit but not the paddle */ if (j < (getHeight() -(PADDLE_Y_OFFSET + PADDLE_HEIGHT))){ remove(colider); } } } You can see from the title of the method that I started with good intentions of "building the ball". There are a few issues I ran up against: The problem is that then I needed to move the ball, so I created that while loop. I don't see any other way to do that other than just keep it "true", so that means any other code I create below this loop won't happen. I didn't make the while loop a different function because I was using those variables i and j. So I don't see how I can refactor beyond this loop. So my main question is: How would I pass the values of i and j to a new method: "animateBall" and how would I use ball.move(vx + vx, vy + vy); in that new method if ball has been declared in the buildBall method? I understand this is probably a simple thing of better understanding variable scope and passing arguments, but I'm not quite there yet...

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• Java array of arry [matrix] of an integer partition with fixed term

  - by user335209

  Hello, for my study purpose I need to build an array of array filled with the partitions of an integer with fixed term. That is given an integer, suppose 10 and given the fixed number of terms, suppose 5 I need to populate an array like this 10 0 0 0 0 9 0 0 0 1 8 0 0 0 2 7 0 0 0 3 ............ 9 0 0 1 0 8 0 0 1 1 ............. 7 0 1 1 0 6 0 1 1 1 ............ ........... 0 6 1 1 1 ............. 0 0 0 0 10 am pretty new to Java and am getting confused with all the for loops. Right now my code can do the partition of the integer but unfortunately it is not with fixed term public class Partition { private static int[] riga; private static void printPartition(int[] p, int n) { for (int i= 0; i < n; i++) System.out.print(p[i]+" "); System.out.println(); } private static void partition(int[] p, int n, int m, int i) { if (n == 0) printPartition(p, i); else for (int k= m; k > 0; k--) { p[i]= k; partition(p, n-k, n-k, i+1); } } public static void main(String[] args) { riga = new int[6]; for(int i = 0; i<riga.length; i++){ riga[i] = 0; } partition(riga, 6, 1, 0); } } the output I get it from is like this: 1 5 1 4 1 1 3 2 1 3 1 1 1 2 3 1 2 2 1 1 2 1 2 1 2 1 1 1 what i'm actually trying to understand how to proceed is to have it with a fixed terms which would be the columns of my array. So, am stuck with trying to get a way to make it less dynamic. Any help?

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• Improving performance for WRITE operation on Oracle DB in Java

  - by Lucky

  I've a typical scenario & need to understand best possible way to handle this, so here it goes - I'm developing a solution that will retrieve data from a remote SOAP based web service & will then push this data to an Oracle database on network. Also, this will be a scheduled task that will execute every 15 minutes. I've event queues on remote service that contains the INSERT/UPDATE/DELETE operations that have been done since last retrieval, & once I retrieve the events for last 15 minutes, it again add events for next retrieval. Now, its just pushing data to Oracle so all my interactions are INSERT & UPDATE statements. There are around 60 tables on Oracle with some of them having 100+ columns. Moreover, for every 15 minutes cycle there would be around 60-70 Inserts, 100+ Updates & 10-20 Deletes. This will be an executable jar file that will terminate after operation & will again start on next 15 minutes cycle. So, I need to understand how should I handle WRITE operations (best practices) to improve performance for this application as whole ? Current Test Code (on every cycle) - Connects to remote service to get events. Creates a connection with DB (single connection object). Identifies the type of operation (INSERT/UPDATE/DELETE) & table on which it is done. After above, calls the respective method based on type of operation & table. Uses Preparedstatement with positional parameters, & retrieves each column value from remote service & assigns that to statement parameters. Commits the statement & returns to get event class to process next event. Above is repeated till all the retrieved events are processed after which program closes & then starts on next cycle & everything repeats again. Thanks for help !

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• Customs toString in Java not giving desired output and throwing error

  - by user2972048

  I am writing a program in Java to accept and validate dates according to the Gregorian Calendar. My public boolean setDate(String aDate) function for an incorrect entry is suppose to change the boolean goodDate variable to false. That variable is suppose tell the toString function, when called, to output "Invalid Entry" but it does not. My public boolean setDate(int d, int m, int y) function works fine though. I've only included the problem parts as its a long piece of code. Thanks public boolean setDate(int day, int month, int year){ // If 1 <= day <= 31, 1 <= month <= 12, and 0 <= year <= 9999 & the day match with the month // then set object to this date and return true // Otherwise,return false (and do nothing) boolean correct = isTrueDate(day, month, year); if(correct){ this.day = day; this.month = month; this.year = year; return true; }else{ goodDate = false; return false; } //return false; } public boolean setDate(String aDate){ // If aDate is of the form "dd/mm/yyyy" or "d/mm/yyyy" // Then set the object to this date and return true. // Otherwise, return false (and do nothing) Date d = new Date(aDate); boolean correct = isTrueDate(d.day, d.month, d.year); if(correct){ this.day = d.day; this.month = d.month; this.year = d.year; return true; }else{ goodDate = false; return false; } } public String toString(){ // outputs a String of the form "dd/mm/yyyy" // where dd must be 2 digits (with leading zero if needed) // mm must be 2 digits (with leading zero if needed) // yyyy must be 4 digits (with leading zeros if needed) String day1; String month1; String year1; if(day<10){ day1 = "0" + Integer.toString(this.day); } else{ day1 = Integer.toString(this.day); } if(month<10){ month1 = "0" + Integer.toString(this.month); } else{ month1 = Integer.toString(this.month); } if(year<10){ year1 = "00" + Integer.toString(this.year); } else{ year1 = Integer.toString(this.year); } if(goodDate){ return day1 +"/" +month1 +"/" + year1; }else{ goodDate = true; return "Invalid Entry"; } } Thank you

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• Java issues with Apache 2.0 Agent 2.202 for RHEL5 Linux 64bit

  - by Richard

  In trying to install Apache 2.0 Agent 2.202 for RHEL5 Linux 64bit, the dialogue appears as follows. $ ./setup Error : java is not present in path. Please enter JAVAHOME path to pick up java:/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/ Launching installer... Attach to native process failed $ ./setup Error : java is not present in path. Please enter JAVAHOME path to pick up java:/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/lib ./setup: line 80: [: 107:: integer expression expected ./setup: line 83: [: 107:: integer expression expected Error : Incorrect java version (1.2.2 or above is needed). Please enter JAVAHOME path to pick up java: On the server we have the following JREs and I've tried both. $ sudo rpm -qa | egrep "(openjdk|icedtea)" java-1.6.0-openjdk-1.6.0.0-1.27.1.10.8.el5_8 $ find 2>/dev/null | grep -i '/jre/' ./usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre/bin/ ... ./usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/ Any suggestions? I know I'm overlooking something. In previous searches I've only found one other posting that comes close but it has no responses (http://forum.parallels.com/showthread.php?t=76556).

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• Looking for Kiosk-style / camera store easy photo memory card to CD/DVD burning program for Windows-7 Notebook? For non techie user.

  - by Rob

  I'm looking for a Kiosk-style / camera shop easy photo memory card to CD/DVD burning program? For non technie user. The kind of system you see in a camera shop / store, e.g. in the UK, Jessops and Boots stores. This is for my Dad who is adept at general PC usage as a notebook owner, but would prefer something fairly simple. The task of burning photos to CD/DVD, in their original photo file .jpg form, i.e. NOT as CD or DVD video or slideshow, is what I'm looking for. I'm guessing this might be possible in Picasa, but all the options available might be superfluous and confusing. He could probably learn to use that but thought I would try simpler options first. Looking for something that guides the user through the steps/stages of the process, 'Wizard' style. Any suggestions? Platform: HP Windows 7 Home notebook with CD/DVD burner and SD memory card slot.

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• How To Completely Move Users/Program Files/Program Files (x86)/ProgramData (Folders) To Another Partition(s) On Windows 8?

  - by Enigma83

  I am attempting to move folders Users Program Files Program Files (x86), ProgramData (at the root of the C drive) to at least 2 other partitions, preferably on a fresh install. I have read that there are methods for doing this post-install, but it seems like it would be a bit more tedious to do things that way. I want to move the 2 Program Files folders to another partition on the same HDD, and Users/ProgramData will go to yet another partition on same HDD. I have done a bit of research on this, read up on some things that involved booting into Audit Mode, using the RoboCopy command to copy folders via booting into my Windows 8 USB drive, creating NTFS junctions/symbolic links, Registry edits, as well as accomplishing this automatically by creating an auto-attend file which Windows Setup processes automatically before the user is ever booted in for the 1st time. I tried this morning and now have a basic installation in which programs like Internet Explorer fail to open, certain files can't be found/opened (even if I click on them directly), an example is Regedit. Also, I can't run the Command/DOS (CMD) prompt as Administrator (or otherwise, as any other user), can't activate the real Administrator account or open any of the Administrative Tools (despite having added them to my Start Screen). So far I have only tried RoboCopy-ing Program Files and Program Files (x86) so far, creating junction points for them, and editing the Registry in the relevant locations. This is what I'm left with now. I also found the following blog article which describes how to do this for Windows 7 So, where should I go from here and where can I find more information? And how can this be done without disabling the Metro apps, which I've read will stop working if you move ProgramData. Once I have everything moved, where do I install programs to? Do I tell them to install to C:\Program Files\Program Files (x86) or to the junctioned/symbolic-linked partition/drive? I plan to test in VMware virtual machines from here on until things are working correctly, while using a baseline default install for daily tasks.

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• JavaOne Tutorial Report - JavaFX 2 – A Java Developer’s Guide

  - by Janice J. Heiss

  Oracle Java Technology Evangelist Stephen Chin and Independent Consultant Peter Pilgrim presented a tutorial session intended to help developers get a handle on JavaFX 2. Stephen Chin, a Java Champion, is co-author of the Pro JavaFX Platform 2, while Java Champion Peter Pilgrim is an independent consultant who works out of London.NightHacking with Stephen ChinBefore discussing the tutorial, a note about Chin’s “NightHacking Tour,” wherein from 10/29/12 to 11/11/12, he will be traveling across Europe via motorcycle stopping at JUGs and interviewing Java developers and offering live video streaming of the journey. As he says, “Along the way, I will visit user groups, interviewing interesting folks, and hack on open source projects. The last stop will be the Devoxx conference in Belgium.”It’s a dirty job but someone’s got to do it. His trip will take him from the UK through the Netherlands, Germany, Switzerland, Italy, France, and finally to Devoxx in Belgium. He has interviews lined up with Ben Evans, Trisha Gee, Stephen Coulebourne, Martijn Verburg, Simon Ritter, Bert Ertman, Tony Epple, Adam Bien, Michael Hutterman, Sven Reimers, Andres Almiray, Gerrit Grunewald, Bertrand Boetzmann, Luc Duponcheel, Stephen Janssen, Cheryl Miller, and Andrew Phillips. If you expect to be in Chin’s vicinity at the end of October and in early November, by all means get in touch with him at his site and add your perspective. The more the merrier! Taking the JavaFX PlungeNow to the business at hand. The “JavaFX 2 – A Java Developer’s Guide” tutorial introduced Java developers to the JavaFX 2 platform from the perspective of seasoned Java developers. It demonstrated the breadth of the JavaFX APIs through examples that are built out in the course of the session in an effort to present the basic requirements in using JavaFX to build rich internet applications. Chin began with a quote from Oracle’s Christopher Oliver, the creator of F3, the original version of JavaFX, on the importance of GUIs:“At the end of the day, on the one hand we have computer systems, and on the other, people. Connecting them together, and allowing people to interact with computer systems in a compelling way, requires graphical user interfaces.”Chin explained that JavaFX is about producing an immersive application experience that involves cross-platform animation, video and charting. It can integrate Java, JavaScript and HTML in the same application. The new graphics stack takes advantage of hardware acceleration for 2D and 3D applications. In addition, we can integrate Swing applications using JFXPanel.He reminded attendees that they were building JavaFX apps using pure Java APIs that included builders for declarative construction; in addition, alternative languages can be used for simpler UI creation. In addition, developers can call upon alternative languages such as GroovyFX, ScalaFX and Visage, if they want simpler UI creation. He presented the fundamentals of JavaFX 2.0: properties, lists and binding and then explored primitive, object and FX list collection properties. Properties in JavaFX are observable, lazy and type safe. He then provided an example of property declaration in code.  Pilgrim and Chin explained the architectural structure of JavaFX 2 and its basic properties:JavaFX 2.0 properties – Primitive, Object, and FX List Collection properties. * Primitive Properties* Object Properties* FX List Collection Properties* Properties are:– Observable– Lazy– Type SafeChin and Pilgrim then took attendees through several participatory demos and got deep into the weeds of the code for the two-hour session. At the end, everyone knew a lot more about the inner workings of JavaFX 2.0.

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• java.lang.RuntimeException: Unable to start activity ComponentInfo cannot be cast to android.widget.ZoomControls

  - by Hwl

  I'm new to android development, hope you all can help me. I got this androidVNC viewer source code from internet. When i'm running the androidVNC application in the emulator, it will exit automatically then i get following errors in LogCat. Can anyone one help me? Thanks. FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{android.androidVNC/android.androidVNC.VncCanvasActivity}: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) at android.app.ActivityThread.access$600(ActivityThread.java:122) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4340) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.androidVNC.VncCanvasActivity.onCreate(VncCanvasActivity.java:585) at android.app.Activity.performCreate(Activity.java:4465) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) ... 11 more This is the ZoomControls java file: package com.antlersoft.android.zoomer; import android.content.Context; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.animation.AlphaAnimation; import android.widget.ImageButton; import android.widget.LinearLayout; import android.widget.ZoomButton; public class ZoomControls extends LinearLayout { private final ZoomButton mZoomIn; private final ZoomButton mZoomOut; private final ImageButton mZoomKeyboard; public ZoomControls(Context context) { this(context, null); } public ZoomControls(Context context, AttributeSet attrs) { super(context, attrs); setFocusable(false); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.zoom_controls, this, // we are the parent true); mZoomIn = (ZoomButton) findViewById(R.id.zoomIn); mZoomOut = (ZoomButton) findViewById(R.id.zoomOut); mZoomKeyboard = (ImageButton) findViewById(R.id.zoomKeys); } public void setOnZoomInClickListener(OnClickListener listener) { mZoomIn.setOnClickListener(listener); } public void setOnZoomOutClickListener(OnClickListener listener) { mZoomOut.setOnClickListener(listener); } public void setOnZoomKeyboardClickListener(OnClickListener listener) { mZoomKeyboard.setOnClickListener(listener); } /* * Sets how fast you get zoom events when the user holds down the * zoom in/out buttons. */ public void setZoomSpeed(long speed) { mZoomIn.setZoomSpeed(speed); mZoomOut.setZoomSpeed(speed); } @Override public boolean onTouchEvent(MotionEvent event) { /* Consume all touch events so they don't get dispatched to the view * beneath this view. */ return true; } public void show() { fade(View.VISIBLE, 0.0f, 1.0f); } public void hide() { fade(View.GONE, 1.0f, 0.0f); } private void fade(int visibility, float startAlpha, float endAlpha) { AlphaAnimation anim = new AlphaAnimation(startAlpha, endAlpha); anim.setDuration(500); startAnimation(anim); setVisibility(visibility); } public void setIsZoomInEnabled(boolean isEnabled) { mZoomIn.setEnabled(isEnabled); } public void setIsZoomOutEnabled(boolean isEnabled) { mZoomOut.setEnabled(isEnabled); } @Override public boolean hasFocus() { return mZoomIn.hasFocus() || mZoomOut.hasFocus(); } } This is the zoom_controls XML file: <merge xmlns:android="http://schemas.android.com/apk/res/android"> <ZoomButton android:id="@+id/zoomOut" android:background="@drawable/btn_zoom_down" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ImageButton android:id="@+id/zoomKeys" android:background="@android:drawable/ic_dialog_dialer" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ZoomButton android:id="@+id/zoomIn" android:background="@drawable/btn_zoom_up" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </merge>

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• Good JDBC pattern

  - by Java Developer

  What is the good practice for database operation in Java application? Do you construct the DML syntax in the Java code and send the statements to DB engine for execution, or you just collect the parameters and then make a call to stored procedure with the parameters via java code? or neither because that's just not how to do it? can anyone give an example of a full database utility classes to do database operations in Java app? also what about the transaction manager? My assignment is to make database operation that is modular in Java. Thanks

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• Java: micro-optimizing array manipulation

  - by Martin Wiboe

  Hello all, I am trying to make a Java port of a simple feed-forward neural network. This obviously involves lots of numeric calculations, so I am trying to optimize my central loop as much as possible. The results should be correct within the limits of the float data type. My current code looks as follows (error handling & initialization removed): /** * Simple implementation of a feedforward neural network. The network supports * including a bias neuron with a constant output of 1.0 and weighted synapses * to hidden and output layers. * * @author Martin Wiboe */ public class FeedForwardNetwork { private final int outputNeurons; // No of neurons in output layer private final int inputNeurons; // No of neurons in input layer private int largestLayerNeurons; // No of neurons in largest layer private final int numberLayers; // No of layers private final int[] neuronCounts; // Neuron count in each layer, 0 is input // layer. private final float[][][] fWeights; // Weights between neurons. // fWeight[fromLayer][fromNeuron][toNeuron] // is the weight from fromNeuron in // fromLayer to toNeuron in layer // fromLayer+1. private float[][] neuronOutput; // Temporary storage of output from previous layer public float[] compute(float[] input) { // Copy input values to input layer output for (int i = 0; i < inputNeurons; i++) { neuronOutput[0][i] = input[i]; } // Loop through layers for (int layer = 1; layer < numberLayers; layer++) { // Loop over neurons in the layer and determine weighted input sum for (int neuron = 0; neuron < neuronCounts[layer]; neuron++) { // Bias neuron is the last neuron in the previous layer int biasNeuron = neuronCounts[layer - 1]; // Get weighted input from bias neuron - output is always 1.0 float activation = 1.0F * fWeights[layer - 1][biasNeuron][neuron]; // Get weighted inputs from rest of neurons in previous layer for (int inputNeuron = 0; inputNeuron < biasNeuron; inputNeuron++) { activation += neuronOutput[layer-1][inputNeuron] * fWeights[layer - 1][inputNeuron][neuron]; } // Store neuron output for next round of computation neuronOutput[layer][neuron] = sigmoid(activation); } } // Return output from network = output from last layer float[] result = new float[outputNeurons]; for (int i = 0; i < outputNeurons; i++) result[i] = neuronOutput[numberLayers - 1][i]; return result; } private final static float sigmoid(final float input) { return (float) (1.0F / (1.0F + Math.exp(-1.0F * input))); } } I am running the JVM with the -server option, and as of now my code is between 25% and 50% slower than similar C code. What can I do to improve this situation? Thank you, Martin Wiboe

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• boolean in java: what am I doing wrong?

  - by Cheesegraterr

  Hello, I am trying to make my boolean value work. I am new at programming java so I must be missing something simple. I am trying to make it so that if one of the tire pressures is below 35 or over 45 the system outputs "bad inflation" For class me must use a boolean which is what I tried. I cant figure out why this isnt working. No matter what I do the boolean is always true. Any tips? public class tirePressure { private static double getDoubleSystem1 () //Private routine to simply read a double in from the command line { String myInput1 = null; //Store the string that is read form the command line double numInput1 = 0; //Used to store the converted string into an double BufferedReader mySystem; //Buffer to store input mySystem = new BufferedReader (new InputStreamReader (System.in)); // creates a connection to system files or cmd try { myInput1 = mySystem.readLine (); //reads in data from console myInput1 = myInput1.trim (); //trim command cuts off unneccesary inputs } catch (IOException e) //checks for errors { System.out.println ("IOException: " + e); return -1; } numInput1 = Double.parseDouble (myInput1); //converts the string to an double return numInput1; //return double value to main program } static public void main (String[] args) { double TireFR; //double to store input from console double TireFL; double TireBR; double TireBL; boolean goodPressure; goodPressure = false; System.out.println ("Tire Pressure Checker"); System.out.println (" "); System.out.print ("Enter pressure of front left tire:"); TireFL = getDoubleSystem1 (); //read in an double from the user if (TireFL < 35 || TireFL > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } System.out.print ("Enter pressure of front right tire:"); TireFR = getDoubleSystem1 (); //read in an double from the user if (TireFR < 35 || TireFR > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } if (TireFL == TireFR) System.out.print (" "); else System.out.println ("Front tire pressures do not match"); System.out.println (" "); System.out.print ("Enter pressure of back left tire:"); TireBL = getDoubleSystem1 (); //read in an double from the user if (TireBL < 35 || TireBL > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } System.out.print ("Enter pressure of back right tire:"); TireBR = getDoubleSystem1 (); //read in an double from the user if (TireBR < 35 || TireBR > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } if (TireBL == TireBR) System.out.print (" "); else System.out.println ("Back tire pressures do not match"); if (goodPressure = true) System.out.println ("Inflation is OK."); else System.out.println ("Inflation is BAD."); System.out.println (goodPressure); } //mainmethod } // tirePressure Class

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• Radix sort in java help

  - by endif

  Hi i need some help to improve my code. I am trying to use Radixsort to sort array of 10 numbers (for example) in increasing order. When i run the program with array of size 10 and put 10 random int numbers in like 70 309 450 279 799 192 586 609 54 657 i get this out: 450 309 192 279 54 192 586 657 54 609 Don´t see where my error is in the code. class IntQueue { static class Hlekkur { int tala; Hlekkur naest; } Hlekkur fyrsti; Hlekkur sidasti; int n; public IntQueue() { fyrsti = sidasti = null; } // First number in queue. public int first() { return fyrsti.tala; } public int get() { int res = fyrsti.tala; n--; if( fyrsti == sidasti ) fyrsti = sidasti = null; else fyrsti = fyrsti.naest; return res; } public void put( int i ) { Hlekkur nyr = new Hlekkur(); n++; nyr.tala = i; if( sidasti==null ) f yrsti = sidasti = nyr; else { sidasti.naest = nyr; sidasti = nyr; } } public int count() { return n; } public static void radixSort(int [] q, int n, int d){ IntQueue [] queue = new IntQueue[n]; for (int k = 0; k < n; k++){ queue[k] = new IntQueue(); } for (int i = d-1; i >=0; i--){ for (int j = 0; j < n; j++){ while(queue[j].count() != 0) { queue[j].get(); } } for (int index = 0; index < n; index++){ // trying to look at one of three digit to sort after. int v=1; int digit = (q[index]/v)%10; v*=10; queue[digit].put(q[index]); } for (int p = 0; p < n; p++){ while(queue[p].count() != 0) { q[p] = (queue[p].get()); } } } } } I am also thinking can I let the function take one queue as an argument and on return that queue is in increasing order? If so how? Please help. Sorry if my english is bad not so good in it. Please let know if you need more details. import java.util.Random; public class RadTest extends IntQueue { public static void main(String[] args) { int [] q = new int[10]; Random r = new Random(); int t = 0; int size = 10; while(t != size) { q[t] = (r.nextInt(1000)); t++; } for(int i = 0; i!= size; i++) { System.out.println(q[i]); } System.out.println("Radad: \n"); radixSort(q,size,3); for(int i = 0; i!= size; i++) { System.out.println(q[i]); } } } Hope this is what you were talking about...

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• DoubleBuffering in Java

  - by DDP

  Hello there, I'm having some trouble implementing DoubleBuffer into my program. Before you faint from the wall of text, you should know that a lot of it is there just in case you need to know. The actual place where I think I'm having problems is in one method. I've recently looked up a tutorial on the gpwiki about double buffering, and decided to try and implement the code they had into the code I have that I'm trying to implement doublebuffer in. I get the following error: "java.lang.IllegalStateException: Component must have a valid peer". I don't know if it makes any difference if you know it or not, but the following is the code with the main method. This is just a Frame that displays the ChronosDisplay class inside it. I omitted irrelevant code with "..." public class CDM extends JFrame { public CDM(String str) { super("CD:M - "+str); try { ... ChronosDisplay theGame = new ChronosDisplay(str); ((Component)theGame).setFocusable(true); add(theGame); } catch(Exception e) { System.out.println("CDM ERROR: " +e); } } public static void main( String args[] ) { CDM run = new CDM("DP_Mini"); } } Here is the code where I think the problem resides (I think the problem is in the paint() method). This class is displayed in the CDM class public class ChronosDisplay extends Canvas implements Runnable { String mapName; public ChronosDisplay (String str) { mapName = str; new Thread(this).start(); setVisible(true); createBufferStrategy(2); } public void paint( Graphics window ) { BufferStrategy b = getBufferStrategy(); Graphics g = null; window.setColor(Color.white); try { g = b.getDrawGraphics(); paintMap(g); paintUnits(g); paintBullets(g); } finally { g.dispose(); } b.show(); Toolkit.getDefaultToolkit().sync(); } public void paintMap( Graphics window ) { TowerMap m = new TowerMap(); try { m = new TowerMap(mapName); for(int x=0; x<m.getRows()*50; x+=50) { for(int y = 0; y<m.getCols()*50; y+=50) { int tileType = m.getLocation(x/50,y/50); Image img; if(tileType == 0) { Tile0 t = new Tile0(x,y); t.draw(window); } ...// More similar if statements for other integers } catch(Exception e) ... } ...// Additional methods not shown here public void run() { try { while(true) { Thread.currentThread().sleep(20); repaint(); } } catch(Exception e) ... } } If you're curious (I doubt it matters), the draw() method in the Tile0 class is: public void draw( Graphics window ) { window.drawImage(img,getX(),getY(),50,50,null); } Any pointers, tips, or solutions are greatly appreciated. Thanks for your time! :D

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• Java multiple class compositing and boiler plate reduction

  - by h2g2java

  We all know why Java does/should not have multiple inheritance. So this is not questioning about what has already been debated till-cows-come-home. This discusses what we would do when we wish to create a class that has the characteristics of two or more other classes. Probably, most of us would do this to "inherit" from three classes. For simplicity, I left out the constructor.: class Car extends Vehicle { final public Transport transport; final public Machine machine; } So that, Car class directly inherits methods and objects of Vehicle class, but would have to refer to transport and machine explicitly to refer to objects instantiated in Transport and Machine. Car car = new Car(); car.drive(); // from Vehicle car.transport.isAmphibious(); // from Transport car.machine.getCO2Footprint(); // from Machine I thought this was a good idea until when I encounter frameworks that require setter and getter methods. For example, the XML <Car amphibious='false' footPrint='1000' model='Fordstatic999'/> would look for the methods setAmphibious(..), setFootPrint(..) and setModel(..). Therefore, I have to project the methods from Transport and Machine classes class Car extends Vehicle { final public Transport transport; final public Machine machine; public void setAmphibious(boolean b){ this.transport.setAmphibious(b); } public void setFootPrint(String fp){ this.machine.setFootPrint(fp); } } This is OK, if there were just a few characteristics. Right now, I am trying to adapt all of SmartGWT into GWT UIBinder, especially those classes that are not a GWT widget. There are lots of characteristics to project. Wouldn't it be nice if there exists some form of annotation framework that is like this: class Car extends Vehicle @projects {Transport @projects{Machine @projects Guzzler}} { /* No need to explicitly instantiate Transport, Machine or Guzzler */ .... } Where, in case of common names of characteristics exist, the characteristics of Machine would take precedence Guzzler's, and Transport's would have precedence over Machine's, and Vehicle's would have precedence over Transport's. The annotation framework would then instantiate Transport, Machine and Guzzler as hidden members of Car and expand to break-out the protected/public characteristics, in the precedence dictated by the @project annotation sequence, into actual source code or into byte-code. Preferably into byte-code. So that the setFootPrint method is found in both Machine and Guzzler, only that of Machine's would be projected. Questions: Don't you think this is a good idea to have such a framework? Does such a framework already exist? Tell me where/what. Is there an eclipse plugin that does it? Is there a proposal or plan anywhere that you know about such an annotation framework? It would be wonderful too, if the annotation/plugin framework lets me specify that boolean, int, or whatever else needs to be converted from String and does the conversion/parsing for me too. Please advise, somebody. I hope wording of my question was clear enough. Thx. Edited: To avoid OO enthusiasts jumping to conclusion, I have renamed the title of this question.

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