I'm working on a program that uses an ArrayList to store Strings. The program prompts the user with a menu and allows the user to choose an operation to perform. Such operations are adding Strings to the List, printing the entries etc. What I want to be able to do is create a method called removeDuplicates().This method will search the ArrayList and remove any duplicated values. I want to leave one instance of the duplicated value(s) within the list. I also want this method to return the total number of duplicates removed.
I've been trying to use nested loops to accomplish this but I've been running into trouble because when entries get deleted, the indexing of the ArrayList gets altered and things don't work as they should. I know conceptually what I need to do but I'm having trouble implementing this idea in code.
Here is some pseudo code:
start with first entry;
check each subsequent entry in the list and see if it matches the first entry;
remove each subsequent entry in the list that matches the first entry;
after all entries have been examined, move on to the second entry;
check each entry in the list and see if it matches the second entry;
remove each entry in the list that matches the second entry;
repeat for entry in the list
Here's the code I have so far:
public int removeDuplicates()
{
int duplicates = 0;
for ( int i = 0; i < strings.size(); i++ )
{
for ( int j = 0; j < strings.size(); j++ )
{
if ( i == j )
{
// i & j refer to same entry so do nothing
}
else if ( strings.get( j ).equals( strings.get( i ) ) )
{
strings.remove( j );
duplicates++;
}
}
}
return duplicates;
}
I use next code to print current time
Calendar cal = Calendar.getInstance();
System.out.println(cal.getTime());
I have Windows XP sp3 istalled. Current time in system tray is 14:30. But this code return 13:30
Why returned time is wrong?
I want to store an object from my class in file, and after that to be able to load the object from this file. But somewhere I am making a mistake(s) and cannot figure out where. May I receive some help?
public class GameManagerSystem implements GameManager, Serializable {
private static final long serialVersionUID = -5966618586666474164L;
HashMap<Game, GameStatus> games;
HashMap<Ticket, ArrayList<Object>> baggage;
HashSet<Ticket> bookedTickets;
Place place;
public GameManagerSystem(Place place) {
super();
this.games = new HashMap<Game, GameStatus>();
this.baggage = new HashMap<Ticket, ArrayList<Object>>();
this.bookedTickets = new HashSet<Ticket>();
this.place = place;
}
public static GameManager createManagerSystem(Game at) {
return new GameManagerSystem(at);
}
public boolean store(File f) {
try {
FileOutputStream fos = new FileOutputStream(f);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(games);
oos.writeObject(bookedTickets);
oos.writeObject(baggage);
oos.close();
fos.close();
} catch (IOException ex) {
return false;
}
return true;
}
public boolean load(File f) {
try {
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
this.games = (HashMap<Game,GameStatus>)ois.readObject();
this.bookedTickets = (HashSet<Ticket>)ois.readObject();
this.baggage = (HashMap<Ticket,ArrayList<Object>>)ois.readObject();
ois.close();
fis.close();
} catch (IOException e) {
return false;
} catch (ClassNotFoundException e) {
return false;
}
return true;
}
.
.
.
}
public class JUnitDemo {
GameManager manager;
@Before
public void setUp() {
manager = GameManagerSystem.createManagerSystem(Place.ENG);
}
@Test
public void testStore() {
Game g = new Game(new Date(), Teams.LIONS, Teams.SHARKS);
manager.registerGame(g);
File file = new File("file.ser");
assertTrue(airport.store(file));
}
}
I have:
Image i = Image.getInstance("tabelka.png");
i.scalePercent(25, 25);
for(int i=0; i<= 5; i++)
{
doc.add(i);
content.moveTo(50, ??);////// <-------------- HOW TO CHECK THE Y POSITION
content.showText("skowron-line");
}
I want to set text on upper right corner of image. How do I do that?
EIDT:
After hours of thinkin i found dirty solution:
Image img = Image.getInstance("tabelka.png");
img.scalePercent(25, 25);
float start = x;
for(int i =1; i<= 5; i++)
{
start = (x - (img.getHeight() * 0.25f) * i);
}
If U know better solution let me know.
I am using this code to find the MAC address of a machine.This code prints directly the MAC address, but i want to return it as a string.I am completely confused.
please help.
try {
InetAddress add = InetAddress.getByName("10.123.96.102");
NetworkInterface ni1 = NetworkInterface.getByInetAddress(add);
if (ni1 != null) {
byte[] mac1 = ni1.getHardwareAddress();
if (mac1 != null) {
for (int k = 0; k < mac1.length; k++) {
System.out.format("%02X%s", mac1[k], (k < mac1.length - 1) ? "-" : "");
}
} else {
System.out.println("Address doesn't exist ");
}
System.out.println();
} else {
System.out.println("address is not found.");
}
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (SocketException e) {
e.printStackTrace();
}
Hello,
I am wondering when to use static methods? Say If i have a class with a few getters and setters, a method or two, and i want those methods only to be invokable on an instance object of the class. Does this mean i should use a static method?
e.g
Obj x = new Obj();
x.someMethod
or
Obj.someMethod
(is this the static way?)
I'm rather confused!
Please explain the output of the below code:
If I call th1.run() ,the output is
EXTENDS RUN
RUNNABLE RUN
If I call th1.start() , the output is :
RUNNABLE RUN
EXTENDS RUN
Why this inconsistency . Please explain.
class ThreadExample extends Thread{
public void run(){
System.out.println("EXTENDS RUN");
}
}
class ThreadExampleRunnable implements Runnable {
public void run(){
System.out.println("RUNNABLE RUN ");
}
}
class ThreadExampleMain{
public static void main(String[] args){
ThreadExample th1 = new ThreadExample();
//th1.start();
th1.run();
ThreadExampleRunnable th2 = new ThreadExampleRunnable();
th2.run();
}
}
This is my code...
class info{
public static void main (String[]args) throws IOException{
char gen;
while(true) { //problem occurs with this while
System.out.print("\nENTER YOUR GENDER (M/F) : ");
gen=(char)System.in.read();
if(gen=='M' || gen=='F' || gen=='m' || gen=='f'){
break;
}
}
System.out.println("\nGENDER = "+gen);
}
}
This is my output...
ENTER YOUR GENDER (M/F) : h
ENTER YOUR GENDER (M/F) :
ENTER YOUR GENDER (M/F) :
ENTER YOUR GENDER (M/F) : m
GENDER = m
Could someone please help me understand why it is asking for the gender so many times.
Hy ,what i`m trying to do is something like this:
private class aClass
{
private ArrayList idProd;
aClass(ArrayList prd)
{
this.idProd=new ArrayList(prd);
}
public ArrayList getIdProd()
{
return this.idProd;
}
}
So if i have multiple instances of ArrayLIst (st1 ,st2 ,st3) and I want to make new objects of aClass :
{
aClass obj1,obj2,obj3;
obj1=new aClass(st1);
obj2=new aClass(st2);
obj3=new aClass(st3);
}why all of the aClass objects will return st3 if I access the method getIdProd() for each of them(obj1..obj3)? is an arraylist as a instance variable automatically declared static?
Hi, what is the best practice or best way of passing form parameters from page to page in a flow? If I have a flow where a user enters data in a form and hits next and repeats this process until they get to an approval page, what ways could I approach this problem to make the retention of data as simple as possible over the flow?
I guess you could put all the information as you go in the session but could you get into memory issues if a lot of people are using your app and going through the flow at the same time?
I know that when creating buttons, like next and previous, that the code can be somewhat long to get those buttons to function.
My professor gave us this example to create the next button:
private void jbtnNext_Click() {
JOptionPane.showMessageDialog(null, "Next" ,"Button Pressed",
JOptionPane.INFORMATION_MESSAGE);
try {
if (rset.next()) {
fillTextFields(false);
}else{
//Display result in a dialog box
JOptionPane.showMessageDialog(null, "Not found");
}
}
catch (SQLException ex) {
ex.printStackTrace();
}
}
Though, I do not really understand how that short and simple if statement is what makes the next button function. I see that the fillTextFields(false) uses a boolean value and that you need to initialize that boolean value in the beginning of the code I believe. I had put private fillTextFields boolean = false; but this does not seem to be right...
I'm just hoping someone could explain it better. Thanks :)
public class b {
public static void main(String[] args) {
byte b = 1;
long l = 127;
// b = b + l; // 1 if I try this then it does not compile
b += l; // 2 if I try this then it does compile
System.out.println(b);
}
}
I am using this code but I have problem:
I don't understand why b=b+l; is not compiling but if I write b+=l; then it compiles and runs.
Please explain why this happens.
I want to create a program for generating the series for the given base-n. ,
for example if my input is 2,then series shuould be, 00,01,10,11,etc.,(binary)
if my input is 10,then series shuould be,1,2,3,4,5,etc.,(decimal)
is there any general mechanism to find these numbers so that I can program for base-n.,
hi everyone,
I work on inheritence with GUI (graphical user interfaces)
let me explain for example I made super class which is vehicle and the subclass is car, so the code to make inheritence will be
public class Car extends Vehicle
then I want to build the class Car as JFrame like
public class Car JFrame implements ActionListener {
so the problem is that I couldn't put both codes in the same class, and I need to do that.
anyone help me. thanks in advance
I wish that the question would be clear
type first integer , type second integer, , program repeatedly outputs the second value of the number of times indicated by the first value. Example use inputs 4 and 2, 222 2 displayed. another example user inputs 3 and 8 , 88 8 displayed
about = new JMenuItem("About");
about.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_A((Toolkit.getDefaultToolkit().getMenuShortcutMask()))));
JMenu help = new JMenu("Help");
help.add(about);
I was wondering why my aaccelerators were not working. I am running this in snow leopard with JavaSe-1.6 VM. They do work if I pull the menu down then try the key sequence. Thanks
Hello
I have this configuration for ehCache:
<ehcache>
<defaultCache
name="defaut"
maxElementsInMemory="5"
eternal="false"
timeToIdleSeconds="20"
timeToLiveSeconds="20"
overflowToDisk="false"
diskPersistent="false"
memoryStoreEvictionPolicy="LRU"
/>
</ehcache>
How can I get access to default cache of EhCache?
CacheManager.getInstance().getCache("default") - returns null
thank you
i have the following class:
public class NewGameContract {
public boolean HomeNewGame = false;
public boolean AwayNewGame = false;
public boolean GameContract(){
if (HomeNewGame && AwayNewGame){
return true;
} else {
return false;
}
}
}
when i try to use it like so:
if (networkConnection){
connect4GameModel.newGameContract.HomeNewGame = true;
boolean status = connect4GameModel.newGameContract.GameContract();
switch (status){
case true:
break;
case false:
break;
}
return;
}
i am getting the error: incompatible types found: boolean required: int on the following switch (status) code.
what am i doing wrong please?
Hi guys,
I have a Spring application that I believe has some bottlenecks, so I'd like to run it with a profiler to measure what functions take how much time. Any recommendations to how I should do that?
I'm running STS, the project is a maven project, and I'm running Spring 3.0.1
Cheers
Nik
Ok, so I'm tyring to iterate through an ArrayList and remove a specefic element. However, I am having some trouble using the For-Each like structure. When I run the following code:
ArrayList<String> arr = new ArrayList<String>();
//... fill with some values (doesn't really matter)
for(String t : arr)
{
t = " some other value "; //hoping this would change the actual array
}
for(String t : arr)
{
System.out.println(t); //however, I still get the same array here
}
My question in, how can I make 't' a pointer to 'arr' so that I am able to change the values in a for-each loop? I know I could loop through the ArrayList using a different structure, but this one looks so clean and readable, it would just be nice to be able to make 't' a pointer.
All comments are appreciated! Even if you say I should just suck it up and use a different construct.
I have a strange problem I've come across. My app can write a simple textfile to SD card and sometimes it works for some people but not for others and I have no idea why. Some people it force closes if they put some characters like "..." in it and such. I cannot seem to reproduce it as I've had no troubles but this is the code that handles it. Can anyone think of something that may lead to problems or a better to way to do it?
public void generateNoteOnSD(String sFileName, String sBody){
try
{
File root = new File(Environment.getExternalStorageDirectory(), "Notes");
if (!root.exists()) {
root.mkdirs();
}
File gpxfile = new File(root, sFileName);
FileWriter writer = new FileWriter(gpxfile);
writer.append(sBody);
writer.flush();
writer.close();
Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show();
}
catch(IOException e)
{
e.printStackTrace();
importError = e.getMessage();
iError();
}
}