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  • Need to split a string into two parts in java

    - by Reddy
    I have a string which contains a contiguous chunk of digits and then a contiguous chunk of characters. I need to split them into two parts (one integer part, and one string). I tried using String.split("\D", 1), but it is eating up first character. I checked all the String API and didn't find a suitable method. Is there any method for doing this thing?

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  • java Swing Listeners: components listening at each others.

    - by Pierre
    Hi all, I want to code two JList (categories and items). When I click one category it should select all the items for that category and when I click on one item it should select its categories. So both JList will have a ListSelectionListener listening at each other and changing the selection. Should I fear about some a of "loop" ? Is there a way to tell that an Event has been consumed ? how do people manage that kind of situation ? Thanks

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  • Download Large Files using java

    - by angelina
    Dear All, I M building a application in which i want to download large files on handset (mobile),but if size of file is large i m getting exception socket exception-broken pipe . inputStream = new FileInputStream(path); byte[] buffer = new byte[1024]; int bytesRead = 0; do { bytesRead = inputStream.read(buffer, offset, buffer.length); resp.getOutputStream().write(buffer, 0, bytesRead); } while (bytesRead == buffer.length); resp.getOutputStream().flush(); }

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  • Java: stopping long HTTP operations

    - by kilonet
    I'm using Apache Common library for HTTP operations: HttpClient client = getClient(); PutMethod put = new PutMethod(url); FileRequestEntity countingFileRequestEntity = new FileRequestEntity(file, "application/octet-stream"); put.setRequestEntity(countingFileRequestEntity); client.executeMethod(put); put.releaseConnection(); I wonder how can safely interrup long HTTP operation. Running it in new thread and stopping it seems to be wrong way. HttpMethodBase has abort() method, but I can't understand how to use it because client.executeMethod blocks execution until it complets

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  • Extract two double Values from String using RegEx in Java

    - by tzippy
    I am reading a file by line and need to extract latitude and longitude from it. This how lines can looks: DE 83543 Rott am Inn Bayern BY Oberbayern Landkreis Rosenheim 47.983 12.1278 DE 21147 Hamburg Hamburg HH Kreisfreie Stadt Hamburg 53.55 10 What's for sure is, there are no dots surrounded by digits except for the ones representing the doubles. Unfortunately there are Values without a dot, so it's probably best to check for numbers from the end of the String. thanks for your help!

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  • ConcurentModificationException in Java HashMap

    - by Bear
    Suppose I have two methods in my classes, writeToMap() and processKey() and both methods are called by multiple threads. writeToMap is a method to write something in hashmap and processKey() is used to do sth based on the keySet of HashMap. Inside processKey, I first copy the originalMap before getting the key set. new HashMap<String, Map<String,String>(originalMap).get("xx").keySet(); But I am still getting ConcurrentModificationException even though I always copy the hashmap. Whats the problem?

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  • java phone number validation....

    - by user69514
    Here is my problem: Create a constructor for a telephone number given a string in the form xxx-xxx-xxxx or xxx-xxxx for a local number. Throw an exception if the format is not valid. So I was thinking to validate it using a regular expression, but I don't know if I'm doing it correctly. Also what kind of exception would I have to throw? Do I need to create my own exception? public TelephoneNumber(String aString){ if(isPhoneNumberValid(aString)==true){ StringTokenizer tokens = new StringTokenizer("-"); if(tokens.countTokens()==3){ areaCode = Integer.parseInt(tokens.nextToken()); exchangeCode = Integer.parseInt(tokens.nextToken()); number = Integer.parseInt(tokens.nextToken()); } else if(tokens.countTokens()==2){ exchangeCode = Integer.parseInt(tokens.nextToken()); number = Integer.parseInt(tokens.nextToken()); } else{ //throw an excemption here } } } public static boolean isPhoneNumberValid(String phoneNumber){ boolean isValid = false; //Initialize reg ex for phone number. String expression = "(\\d{3})(\\[-])(\\d{4})$"; CharSequence inputStr = phoneNumber; Pattern pattern = Pattern.compile(expression); Matcher matcher = pattern.matcher(inputStr); if(matcher.matches()){ isValid = true; } return isValid; } Hi sorry, yes this is homework. For this assignments the only valid format are xxx-xxx-xxxx and xxx-xxxx, all other formats (xxx)xxx-xxxx or xxxxxxxxxx are invalid in this case. I would like to know if my regular expression is correct

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  • Java Swing: JTextArea columns question

    - by battousai622
    How do i put the text in specific columns with jTextArea? private javax.swing.JTextArea jTextArea1; jTextArea1.setColumns(4); jTextArea1.insert(price, 0); //column 1 jTextArea1.insert(cost, 0); //column 2 jTextArea1.insert(quantity, 0); //column ect.. jTextArea1.insert(itemName, 0); jTextArea1.insert("\n", 0);

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  • Java: Are these 2 codes the same?

    - by Kevin Duke
    for (Player p : players) { p.addCard(deck.dealCard()); p.addCard(deck.dealCard()); } and for (int i = 0; i < players.size() ; i++) { Player p = players.get(i); p.addCard(deck.dealCard()); p.addCard(deck.dealCard()); } The second code yeilds a null pointer exception, what can be done to make the bottom one equivalent ?

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  • java hashmap array to double array

    - by Tweety
    Hi, I declared LinkedHashMap<String, float[]> and now I want to convert float[] values into double[][]. I am using following code. LinkedHashMap<String, float[]> fData; double data[][] = null; Iterator<String> iter = fData.keySet().iterator(); int i = 0; while (iter.hasNext()) { faName = iter.next(); tValue = fData.get(faName); //data = new double[fData.size()][tValue.length]; for (int j = 0; j < tValue.length; j++) { data[i][j] = tValue[j]; } i++; } When I try to print data System.out.println(Arrays.deepToString(data)); it doesn't show the data :( I tried to debug my code and i figured out that I have to initialize data outside the while loop but then I don't know the array dimensions :( How to solve it? Thanks

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  • Connection and Collection Interfaces in Java

    - by Bhupi
    Which class implements all the Connection Interfaces which are in javax.microedition.io package and how? And in the same way which class implements the some of Collection interfaces like Iterator interface. I saw a code: - Iterator it; ArrayList list = new ArrayList(); it = list.iterator(); The iterator() return type is "Iterator" which is an interface. Please tell me what this code is doing is it returning an object of type Iterator? but as far as I know, interface can't be initialized.

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  • java.lang.NumberFormatException: unable to parse '' as integer one more time

    - by Quzziy
    I will take two numbers from user, but this number from EditText must be converted to int. I think it should be working, but I still have problem with compilation code in Android Studio. CatLog show error in line with: int wiek = Integer.parseInt(wiekEditText.getText().toString()); Below is my full Android code: public class MyActivity extends ActionBarActivity { int Wynik; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_my); int Tmax, RT; EditText wiekEditText = (EditText) findViewById(R.id.inWiek); EditText tspoczEditText = (EditText) findViewById(R.id.inTspocz); int wiek = Integer.parseInt(wiekEditText.getText().toString()); int tspocz = Integer.parseInt(tspoczEditText.getText().toString()); Tmax = 220 - wiek; RT = Tmax - tspocz; Wynik = 70*RT/100 + tspocz; final EditText tempWiekEdit = wiekEditText; TabHost tabHost = (TabHost) findViewById(R.id.tabHost); //Do TabHost'a z layoutu tabHost.setup(); TabHost.TabSpec tabSpec = tabHost.newTabSpec("Calc"); tabSpec.setContent(R.id.Calc); tabSpec.setIndicator("Calc"); tabHost.addTab(tabSpec); tabSpec = tabHost.newTabSpec("Hints"); tabSpec.setContent(R.id.Hints); tabSpec.setIndicator("Hints"); tabHost.addTab(tabSpec); final Button Btn = (Button) findViewById(R.id.Btn); Btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Toast.makeText(getApplicationContext(),"blablabla"+ "Wynik",Toast.LENGTH_SHORT).show(); } }); wiekEditText.addTextChangedListener(new TextWatcher() { @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { Btn.setEnabled(!(tempWiekEdit.getText().toString().trim().isEmpty())); } @Override public void afterTextChanged(Editable s) { } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.my, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }

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  • Freeing Java memory at a specific point in time

    - by Marcus
    Given this code, where we load a lot of data, write it to a file, and then run an exe.. void myMethod() { Map stuff = createMap(); //Consumes 250 MB memory File file = createFileInput(stuff); //Create input for exe runExectuable(file); //Run Windows exe } What is the best way to release the memory consumed by stuff prior to running the exe? We don't need this in memory any more as we have dumped the data to a file for input to the exe... Is the best method to just set stuff = null prior to runExecutable(file)?

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  • Question About Eclipse Java Debugger Conditional Breakpoints Inefficiency

    - by Personman
    I just set a conditional breakpoint in Eclipse's debugger with a mildly inefficient condition by breakpoint standards - checking whether a HashMap's value list (8 elements) contains Double.NaN. This resulted in an extremely noticeable slowdown in performance - after about five minutes, I gave up. Then I copy pasted the condition into an if statement at the exact same line, put a noop in the if, and set a normal breakpoint there. That breakpoint was reached in the expected 20-30 seconds. Is there something special that conditional breakpoints do that is different from this, or is Eclipse's implementation just kinda stupid? It seems like they could fairly easily just do exactly the same thing behind the scenes.

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  • java objects, shared variables

    - by raven
    hello, I have a simple question here. If I declare a variable inside an object which was made [declared] in the main class, like this: public static int number; ( usually I declare it like this : private int number; ) can it be used in a different object which was also made [declared] in the main class? btw I do not care about security atm, I just want to make something work, don't care about protection)

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  • Relating text fields to check boxes in Java

    - by Finzz
    This program requires the user to login and request a database to access. The program then gets a connection object, searches through the database storing the column names into a vector for later use. The problem comes with implementing text fields to allow the user to search for specific values within the database. I can get the check boxes and text fields to appear using a gridlayout and add them to a panel. How do I relate the text fields to their appropriate check box? I've tried adding them to a vector, but then they can't also be added to the panel as well. I've searched for a way to name the text fields as the loop cycles through the column names, but it seems impossible to do without having them declared ahead of time. This can't be done either, as it's impossible to determine the attributes that the user will request. I just need to be able to know the names of the text fields so I can test to see if the user entered information and perform the necessary logic. Let me know if you have to see the rest of the code to give an answer, but hopefully you get the general idea of what I'm trying to accomplish. Picture of UI: try { ResultSet r2 = con.getMetaData().getColumns("", "", rb.getText(), ""); colNames1 = new Vector<String>(); columns1 = new Vector<JCheckBox>(); while (r2.next()) { colNames1.add(r2.getString(4)); JCheckBox cb = new JCheckBox(r2.getString(4)); JTextField tf = new JTextField(10); columns1.add(cb); p3.add(cb); p3.add(tf); } }

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  • JAVA: Can't get context parameters in Filter

    - by DaTval
    Hello, I have a filter and parameters in web.xml web.xml is like this: <filter> <description> </description> <display-name>AllClassFilter</display-name> <filter-name>AllClassFilter</filter-name> <filter-class>com.datval.homework.AllClassFilter</filter-class> <init-param> <param-name>DB_URL</param-name> <param-value>jdbc:derby:C:/Users/admin/workspace/homework03/homework/databases/StudentsDB;create=true</param-value> </init-param> <init-param> <param-name>DB_DIALECT</param-name> <param-value>org.hibernate.dialect.DerbyDialect</param-value> </init-param> <init-param> <param-name>DB_DRIVER</param-name> <param-value>org.apache.derby.jdbc.EmbeddedDriver</param-value> </init-param> </filter> mapping is working well. But I can't get this parameters in my filter. public void init(FilterConfig config) throws ServletException { // TODO Auto-generated method stub debugMessage = config.getInitParameter("debugMessage"); ctx = config.getServletContext(); } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { // TODO Auto-generated method stub // place your code here ctx.log("Start - " + debugMessage); String myDbUrl = ctx.getInitParameter("DB_URL"); String DB_DIALECT = ctx.getInitParameter("DB_DIALECT"); String DB_DRIVER = ctx.getInitParameter("DB_DRIVER"); Map<String,String> pr = new HashMap<String,String>(); pr.put("hibernate.connection.url", myDbUrl); pr.put("hibernate.dialect", DB_DIALECT); pr.put("hibernate.connection.driver_class", DB_DRIVER); EntityManagerFactory emf = Persistence.createEntityManagerFactory("students",pr); EntityManager em = emf.createEntityManager(); request.setAttribute("em", em); chain.doFilter(request, response); em.close(); ctx.log("end - " + debugMessage); } I have checked and myDbUrl is null. What I'm doing wrong? Any idea? Sorry about code, I will change it later :)

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  • Java Flow Control Problem

    - by Kyle_Solo
    I am programming a simple 2d game engine. I've decided how I'd like the engine to function: it will be composed of objects containing "events" that my main game loop will trigger when appropriate. A little more about the structure: Every GameObject has an updateEvent method. objectList is a list of all the objects that will receive update events. Only objects on this list have their updateEvent method called by the game loop. I’m trying to implement this method in the GameObject class (This specification is what I’d like the method to achieve): /** * This method removes a GameObject from objectList. The GameObject * should immediately stop executing code, that is, absolutely no more * code inside update events will be executed for the removed game object. * If necessary, control should transfer to the game loop. * @param go The GameObject to be removed */ public void remove(GameObject go) So if an object tries to remove itself inside of an update event, control should transfer back to the game engine: public void updateEvent() { //object's update event remove(this); System.out.println("Should never reach here!"); } Here’s what I have so far. It works, but the more I read about using exceptions for flow control the less I like it, so I want to see if there are alternatives. Remove Method public void remove(GameObject go) { //add to removedList //flag as removed //throw an exception if removing self from inside an updateEvent } Game Loop for(GameObject go : objectList) { try { if (!go.removed) { go.updateEvent(); } else { //object is scheduled to be removed, do nothing } } catch(ObjectRemovedException e) { //control has been transferred back to the game loop //no need to do anything here } } // now remove the objects that are in removedList from objectList 2 questions: Am I correct in assuming that the only way to implement the stop-right-away part of the remove method as described above is by throwing a custom exception and catching it in the game loop? (I know, using exceptions for flow control is like goto, which is bad. I just can’t think of another way to do what I want!) For the removal from the list itself, it is possible for one object to remove one that is farther down on the list. Currently I’m checking a removed flag before executing any code, and at the end of each pass removing the objects to avoid concurrent modification. Is there a better, preferably instant/non-polling way to do this?

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  • Java, searching within a list of objects?

    - by Rick
    I'm a bit lost on the way to make this happen the fastest. I have a large list of objects that have basic variable attributes (with getters / setters) and I need to do a search in this list to find the objects within the list that match a given parameter I have found how to do a regular list search but I need to, for example search for the value of the result of doing a call getName() for each object in the list and get objects that have a result that matches my input. Something like below where the third argument is the result of the method call and the second is what I am trying to find. int index = Collections.binarySearch(myList, "value", getName()); Any advice is appreciated

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