Swing/AWT/SWT :: Instantiation Of Listener Using Anonymous Inner Class
Jun 2, 2014
JMenuItem blueChoice = new JMenuItem("Blue");
blueChoice.addActionListener(new InnerMenuListener(){
public void actionPerformed(ActionEvent e){
String buttonCommandString = e.getActionCommand( );
if (buttonCommandString.equals("Red"))
redPanel.setBackground(Color.RED);
else if (buttonCommandString.equals("White"))
whitePanel.setBackground(Color.WHITE);
else if (buttonCommandString.equals("Blue"))
bluePanel.setBackground(Color.BLUE);
else
System.out.println("Unexpected error.");
}
});
Can a method in an anonymous inner class ever be private? why or why not?
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Jun 26, 2014
I have two different classes called Login (in the package View) and RegButtonListener (in the package Controller). I want to use the MVC pattern.
Login creates a GUI for login. I used NetBeans GUI Builder to create it.
In the class RegButtonListener there is the code for the click of the buttons, then various listeners of the GUI.
Now I want to close the login frame at the click of a button so I want to use the dispose() method.
If I had all the code (GUI code and code of the listener) in the same file, close the frame would be easy enough to do because this.dispose(). But in my case I have two different classes.
I also have a second problem.
In Login class (in the packege View) I have included the line :
regButton.addActionListener(Controller.RegButtonListener).
However, Netbeans tells me an error "package regButton does not exist. <identifier> expected". Why does he consider regButton a package? How can I fix these two problems?
How do I do then?
Below is the code of the two classes.
Login class.
public class Login extends javax.swing.JFrame {
/** Creates new form Login */
public Login() {
initComponents();
[code]....
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Apr 18, 2014
I am using the DJWebbrowser in a Java Swing Application that I am working on
// Browser addon as Panel
JPanel browser = new JPanel();
browser = (JPanel) util.BPanel.createContent();
wrapper.add(browser);
and am sending data from a Google Map API , Distance Matrix Query with following code
function callback(response, status) {
if (status != google.maps.DistanceMatrixStatus.OK) {
alert('Error was: ' + status);
} else {
var origins = response.originAddresses;
var destinations = response.destinationAddresses;
var outputDiv = document.getElementById('outputDiv');
[code]...
I haven't found a way to access a class property from the class that invoked the web browser, because the above WebBrowserAdapter is in an anonymous Inner Class.´I would like to have the distance that is sent from the Javascript to the application be passed on to the class member "distance" that in the invoking class.
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Jul 29, 2014
I am new to java coding.... When we create anonymous inner class for interface, we get one object for the sublcass of that interface .
In interface there is no constructor then how do we get that object. We know that to create Anonymous inner class we should use one super class constructor.
Whether my understand is correct or not.
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Jun 20, 2014
Wanted to know Is there any way to determine the class of a random anonymous object?
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Jun 22, 2014
In the following program i have called the anonymous class of dev class.
interface emp {
void desig();
}
public class dev implements emp {
dev e = new dev() //this line is throwing error ...works fine if i use emp instead of dev {
[Code] .....
i am getting stack over flow error as :
Exception in thread "main" java.lang.StackOverflowError
at dev$1.<init>(dev.java:17)
at dev.<init>(dev.java:16)
at dev$1.<init>(dev.java:17)
[Code] .....
Is it because the jvm is not able to decide which of the 2 desigs() it has to load in the memory when its object is created in the main..??
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Mar 31, 2014
Couple of problems here...
1. I am trying to use the getSource method in my inner class, in order to set the JPasswordField within an Inner Listener Class. This is a 4 integer password, setup by my for statement in the loop. I know what I want the program to do, but I don't know the correct language to use. I want the user to press one of the keys (0-9), that value be stored in JPassword (at least I think that is how it works) and for it to display the "*" in the Field---I want this to loop 4x. How do I use the getSource() to do this.
Also, I believe I need to use the set and get methods for the password entered into the JPassField, is that correct? The inner class is not recognizing my the object password that represents the JPasswordField.
2. In my second Inner Listener Class, clearButton, I set the event.getSource method to reset the JPasswordField to " ", when the clear button is pressed. Again, the problem is that the inner class does not recognize password. Why is this the case, since it is still a part of the parent class Atm?
Java Code: import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Atm extends JFrame {
Atm(){
super("ATM");
int i = 0;
//Create Panels For ATM
JPanel buttonPanel1 = new JPanel(); //To Contain Digits 1-9
buttonPanel1.setLayout(new GridLayout(4, 3));
[code]...
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May 25, 2014
I have a Jbutton in my application named as SUBMIT,on clicking SUBMIT the text of jButton changes to ABORT. I wish to apply enter key listener on both the SUBMIT and ABORT button in my applcation, however I am not able to get the text of the button in key listener,so that i can apply my code based on the current text of Button.
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Feb 22, 2014
I'm using Eclipse with the Window Builder Pro plugin to create a Java program. I noticed that when I had Eclipse create an action listener for a combobox in a Swing GUI it created an AWT listener.
Did I choose the wrong type of listener? I want my code to use the Swing components because I understand that they are more portable.
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Aug 1, 2014
I have data base connection which i have configured via a listener class i configured properly in DD but still i am not able to deploy the project and server log show that startL.java listener class was not found why is this so as config is proper with the name
here is my server log
[2014-08-01T20:53:59.112+0530] [glassfish 4.0] [SEVERE] [] [javax.enterprise.system.core] [tid: _ThreadID=34 _ThreadName=admin-listener(3)] [timeMillis: 1406906639112] [levelValue: 1000] [[
Exception while loading the app : java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: java.lang.IllegalArgumentException: java.lang.ClassNotFoundException: contpack.startL.java]]
**if i remove the Listener tag then app runs fine**
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Feb 19, 2014
In the book we made a GUI which has 2 buttons, a label and a panel (the panel is a subclass of JPanel). What the program does is the following: When I press one of the two buttons, in the panel there is a rectangle that changes its color. When I press the other button it has to change the text on the label. Now the problem is that when I start the program, the FIRST time I press the button on which the label must change, this also changes the color in the rectangle, which it should not (I also noticed that when i FIRST click the rectangle shifts a little bit to the left). After that the program works fine.
Here is my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TwoButtons{
JFrame fr;
JButton labelButton;
JButton colorButton;
JLabel label;
[Code] ....
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Jan 23, 2015
how it is decided which class will implement a session listener interface? Which class will implement HttpSessionListener? Which one will implement HttpSessionActivationListener, HttpSessionBindingListener or HttpSessionAttributeListener?
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Mar 8, 2014
again i am facing problem i am able to run Listener class also the ContextListener is initialised but it is giving me error on Tomcat 6.0 command prompt
Here is my Listener Class Sample.java i am able to compile the code but it is giving java.lang.nullpointer exception at runtime on Tomcat.exe Is there is problem in my code
package servlet;
import java.io.*;
import java.io.FileInputStream;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
import javax.mail.internet.MimeMessage.*;
import javax.mail.internet.InternetAddress.*;
import java.util.*;
[Code]...
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Jul 14, 2014
I have three JComboBoxes. When the user selects an entry in the first JComboBox the entries in the second are set. For this I use an Action extends AbstractAction which is bound to the first JComboBox.
I have also bound an Action to the second JComboBox.
Problem: this also fires when the entries on the second JCombox are added which leads to a Nullpointer.
I need a Listener which only reacts to user input, and does not react when the model of the JComboBox is changed.
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Sep 22, 2014
I’m teaching myself Java. I am a fairly proficient programmer in other languages, but this is the first OO language I’m doing.I have a question that is a bit hard to summarize. Or it should be: how can I pass on an object (or variable) to an event listener?
I am writing an application in which you can play a Sudoku game. I have separated the “logic” or the “model”(the classes with Sudoku data structures and methods to manipulate them) from the presentation (the view and the controller).The main method starts off as follows:
SudokuModel model = new SudokuModel();
SudokuView viewController = new SudokuViewController(model);
The first line creates class for the logic and the second line creates the class for the view and the controller. Since the view and the controller need access to the business logic, the model is passed on to the ViewController class.The SudokuViewController class creates the user interface in Swing and it handles the user input. For the user input I have created a number of listeners, like this:
table.addKeyListener(this);
Now these listeners need access to the model since they update it. However, as far as I’m aware the only parameter passed on to an event listener is the event itself. So these event listeners do not have direct access to the model, even though it is passed on to the constructor of the class SudokuViewController.
To circumvent this, I made model2 an attribute (variable) of the class SudokuViewController. The constructor of the class sets this variable as follows:
model2 = model;
Now the event listeners have access to model2, which they can manipulate.This works. However, I think it is an ugly solution, introducing an additional object (model2). I’d like to pass on the object named model to the event listener, but this doesn’t seem to be possible.
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Feb 22, 2015
I have buttons created on a frame and then I register the listener from a controller in a controller-view relationship.
When I click the button on the face, the action never executes for some reason. I thought maybe there was a problem registering the listener but I can call the buttons doclick() method and it executes as it should. Perhaps I'm overlooking something really obvious here but I can't see it.
btnEight = new JButton( "8" );
// btnEight.addActionListener( controller );
btnEight.setBounds( 212, 90, 41, 23 );
frame.getContentPane().add( btnEight );
and then I add the listener
public void setController( ActionListener theController ) {
Component[] components = frame.getContentPane().getComponents();
for ( Component component : components ) {
if ( component instanceof JButton ) {
JButton button = ( JButton ) component;
button.addActionListener( theController );
}
}
again, when i click the button nothing happens. but if i add the following code
btnEight.doclick()
the actionPerformed invokes in theController as I intended.
You can see the entire project on GitHub so you can see the full context. The controller class contains the listener and the view class contains the buttons.
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Nov 11, 2014
I need to take the value of what's typed in my JTextField, and once the submit button is clicked, I want to add that string to my JComboBox list items.
Depending which RadioButton they selected, I need to put the team in HOME or AWAY teams, and so on and so on, until they continue clicking submit.
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Jan 25, 2007
I need to change the value only when I press one of the arrows in a JSpinner component.How can I add a listener to the arrow buttons. I tried ChangeListener but it was not what I needed
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Jun 3, 2014
Is there some equivalent of the Swing TreeWillExpand-listener for TreeView?
In my particular case I want to check whether some constrains are set to show some children before they will populated in the view.
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Jan 30, 2015
I have the following listener on a tableset of names:
ListSelectionListener singleListener=new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
int row=e.getFirstIndex();
if (row==previousRow) {
row=-1;
[Code] .....
The println shows that getValueIsAdjusting is called 4 times when I click a single selection from the list. Is this normal behavior? If so how do I determine which call to really use. If not, where can I look to see why it is being called 4 times on a single click?
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Dec 3, 2014
I was developed a simple GUI, in that it requires modification of jtextfield content while JComboBox item selected and vice-versa. I was used itemListener on JComboBox and Document Listener on JTextField. It was gives exception while running the code. Because one listener source effected by another one..
Exceptions are like this:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification
at javax.swing.text.AbstractDocument.writeLock(Unknown Source)
at javax.swing.text.AbstractDocument.replace(Unknown Source)
at javax.swing.text.JTextComponent.setText(Unknown Source)
at ronanki.swing.pcahostsimUI$5.itemStateChanged(pcahostsimUI.java:368)
at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
[Code] ......
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May 17, 2014
I am currently learning Java basic concepts and this is a very simple code which produces error depending on the way I write. It is as follows:
package testPackage;
interface ArrayInsideClassShock {
}
class Check{
ArrayInsideClassShock var[]; //Error line
var= new ArrayInsideClassShock[10];
}
Error in eclipse:Syntax error on token ";", , expected
But if I write it as:
package testPackage;
interface ArrayInsideClassShock {
}
class Check{
ArrayInsideClassShock var[]=new ArrayInsideClassShock[10];
}
It doesn't show any error.
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Nov 18, 2014
So I have a persons class:
public class Person
{
private String name;
private int age;
public Person (String name, int age) {
this.name = name;
this.age = age;
[Code] .....
And I need to write a simple main method that creates lots of instances of the Person class and adds them to a generic instantiation of a Collection (ArrayList). And I need to make it so I as a programmer can define how many instances to create.
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May 17, 2015
Whilst pre-preparing for java certification, one of the online mock exams has slightly confused me by saying my answer was incorrect for multi-dimension array 'declaration and instantiation'.
This is one of the answers i chose - which was marked as incorrect
a)
int[][] array2d = {{123}, {4,5}};
Which looks absolutely fine to me.One of the other answers, which i agree is correct and so does the mock exam is
b)
int [][] array2d = new int[2][2];
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Sep 6, 2014
Where usually to instantiate and declare variables to be used in a loop. If you declare it outside to be used in the loop it will still be there when the loop is done, never to be used again and is just sitting there taking up memory. However, if you declare it inside the loop, you have the issue of it constantly creating space for said variable, but once it's out of scope it's gone. Is there any advantage performance wise to doing it either way?
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Dec 26, 2014
Why do we get such output or which line of code produces the output?
1class Egg2 {
2 protected class Yolk {
3 public Yolk() { print("Egg2.Yolk()"); }
4 public void f() { print("Egg2.Yolk.f()");}
5 }
6 private Yolk y = new Yolk();
[Code] ....
/* Output:
1.)Egg2.Yolk()
2.)New Egg2()
3.)Egg2.Yolk()
4.)BigEgg2.Yolk()
5.)BigEgg2.Yolk.f()
*///:~
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