Instantiating Interface - ActionListener
Dec 25, 2014
I have a snippet here that I'm working with and I have a few questions about it.
button.addActionListener( new ActionListener(){
@Override
public void actionPerformed(ActionEvent ev){
System.out.println("Button Pressed");
}
});
My questions are:
1. How is it possible to use new on ActionListener when ActionListener is an Interface, not a Class. Isn't it illegal to instantiate an Interface?
2. What is going on with the argument to addActionListener? We have the new ActionListener, but we also have a method being defined as well?
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May 21, 2014
I had the question of what this was. [URL] ....
In summary, the Class XCopy's Main method creates an instance of the XCopy Class. So, now knowing that this can and does occur my next questions to myself were:
When would I do this?
How can this best be used?
Is this just another option available to a Java developer that has no other special significance?So far have no answers for myself.
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May 17, 2014
I would like to know what is the significance of instantiating an object without an assignment.
I have created a class TestClass1 with a single constructor that prints a test message.
In TestClass2, if I write "new TestClass1()" rather than "TestClass1 x = new TestClass1()" it still works, and prints the test message.
I would like to know if I do not assign an object at the time of instantiation, it cannot be referenced or reused later, then what is the significance of this type of construct and when it can be useful, and where is the object being held.
public class TestClass1 {
TestClass1() {
System.out.println("This is a test message");
}
}
public class TestClass2 {
[Code] ....
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Dec 14, 2014
I have two classes, MonsterGame (shown below) and Monster. Monster has a public accessor method to get it's private character variable, which represents the first character of the name of the Monster in question.
I'm just a bit confused as to why am I unable to cycle through the array of Monsters I have in the MonsterGame class and call
m.getCharacter(); (pretty much the last line of code)
public class MonsterGame{
private static final char EMPTY_SQUARE = ' ';
private char[][] gameBoard = new char[10][10];
private Monster[] monsters = new Monster[4];
private int maxXBoardSize = gameBoard.length -1;
private int maxYBoardSize = gameBoard[0].length -1;
[Code] ....
I understand that there need to be instances of objects to call methods, but is that not the case here? the Monster objects are have already been created, no? Do I need to create an index for the array? is the for loop not enough?
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Oct 28, 2014
Why I can create an Instance of a class that contains non static variables within the static main method ?
This program runs fine
import java.util.*;
public class Test{
public int j;
public static void main(String[] args) {
Test test1=new Test();
System.out.println(test1.j);
[Code] .....
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Jun 9, 2014
Below code gets printed as output?
public interface I1 {
public void method();
}
public interface I2 {
public void method();
}
public interface I3 extends I2, I1 {
[Code] ....
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Nov 17, 2014
public void paint(Graphics g) {
g2=(Graphics2D)g;
rectangle=new Rectangle(50,50,100,100);
}
public action() {
JFrame frame=new JFrame("Assignment 2");
frame.setSize(700,700);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
[code]....
I'm trying to add shapes on my panel once a button is clicked.The tutorials I found is having only 1 panel & therefore they can use g.drawRect() directly but I have few panels & that's the part I don't know how to implement it.The coding above with (//invalid) is the part I would like to write it out but it's invalid.
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Mar 25, 2015
I am trying to implement user input in my dice rolling program but I do not understand where I need to add the actionListener. What I want the program to do is allow the user to click on each roll button and have the output be between 1 and 6. I figured I can put it in the "main" class due to the size of the program but I would like to know the best way to go about adding the actionListener into a sub-class for practice purposes.Here is my code thus far:
package com.jprogs;
import java.awt.*;
import javax.swing.*;
public class DiceGenerator extends JFrame {
DiceRollEvent dice = new DiceRollEvent();
// create the roll buttons
JButton roll_1 = new JButton("Roll #1");
JButton roll_2 = new JButton("Roll #2");
JButton roll_3 = new JButton("Roll #3");
JButton roll_4 = new JButton("Roll #4");
JButton roll_5 = new JButton("Roll #5");
// create output field for each roll
[code].....
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Mar 31, 2014
I want to make a game and I have the following:
A main JFrame which include some text and a Button (The Start Button), and I made an ActionListener for that Button to another ActionListener which have a for, but when I run the project I only see the final of the for loop.
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Feb 11, 2015
What Is the difference between an ActionListener and an EventHandler ?
button.addActionListener(new ActionListener() {
button.setOnAction(new EventHandler<ActionEvent>() {
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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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Feb 7, 2014
I have a class with jbutton declared inside like these:
public class UI{
private JFrame ventana;
private JTable table;
private JPanel panel;
private JScrollPane tableScrollPane;
private JTextField aBuscar;
[Code] .....
I would like to add actionlistener in my JButton's. Where must I declared these listener. How should I do these?
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Jul 24, 2014
i have a row of int JTextfields and i want to get a running total of the sum of all boxes in the last total JTextfield, as the user types.I understand its an actionlistener but whats the best way of doing it. What the action to listen out for?
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Mar 18, 2015
How can I remove the ActionListener from the buttons of my application after i have got something happen.
Please consider the following application:
Java Code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Exer1218659 extends JFrame {
private String[] textButtons;
private Container contents;
[Code] .....
After the line 37 executes I expect that the ActionHandler (ah) will be removed from all of the buttons but this do not happen, then all the remaining button still responding to the clicks. Where is the problem in my code.
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Jun 21, 2014
In my given below code..in Action listener #Report function does not calling.
Java Code:
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
[Code] ....
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Nov 27, 2014
I was working on implementing the game Hunting the Wumpus [URL] .... for one of my projects in College. I've got the major parts of the game already implemented. I am working on creating a start screen right now. But I've run into a strange problem. In my code the main method that draws is the PaintComponent method in the private class HTWPanel. I need the Actionlistener to listen to the "QWES" keys while the state of the game is PlayState.Playing so that the user can enter the direction he's going in. If I have the following code for my paint component, the Actionlistener works fine.
public void paintComponent(Graphics g) {
super.paintComponent(g);
map.draw(g, 100);
}
But when I try to add a start screen (by changing the background color and adding a label called "StartScreen"), the controller only listens to keys while the start screen is showing, not while the game is playing. I'm pretty sure this problem is due to some internal implementation of KeyAdacpter or ActionListener, but I'm not sure what.
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (state == PlayState.START) {
this.setBackground(Color.orange);
this.add(startScreen);
}
else if (state == PlayState.PLAYING) {
if (this.getBackground() != Color.WHITE) {this.setBackground(Color.WHITE);}
map.draw(g, 100);
}
I attached a screenshot of my main class, HuntTheWumpus, and a screenshot of what my game looks like so far. Each square is a different room in the Wumpus's lair. The black rectangles are door representing which direction you can go to. The rooms that are 2 squares or less from the wumpus are colored red. The hunter is represented by the black circle in the upper left hand square. His he can move left right up and down into different rooms with the "QWES" keys.
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Mar 28, 2014
I've scanned the book and a few other forums trying to find an answer to my particular question (or I simply didn't understand) with no luck. I want to create an ActionListener for my ATM machine, that will both receive the input numbers to check them against the passcode for a predefined user, but also add the typical " * " that we see when performing such an action.
1. I have created individual objects for each button, which I then used in the constructor "perform" from class action. I'm not sure where to start in the method ActionPerformed.
2. How do I get the asterisks to appear in the JPasswordField each time a numeric button is pressed on the keypad?
Java Code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Atm extends JFrame {
Atm(){
super("ATM");
//Create Panels For ATM
JPanel buttonPanel1 = new JPanel(); //To Contain Digits 1-9
buttonPanel1.setLayout(new GridLayout(4,3));
[code]....
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Mar 5, 2014
I was suspecting I had a jButton not working, so I added a console print to test. See below. When I click the button, the console doesn't display anything. Am I using the button wrong?
private void jButtonUpdateItemsMouseClicked(java.awt.event.MouseEvent evt) {
System.out.println("click");
System.out.println(drawPreviousRectangle);//this is a boolean
}
I have also tried the following with the same results (or lack of).
private void jButtonUpdateMajorDeckItemsActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("click");
System.out.println(drawPreviousRectangle);//this is a boolean
}
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Mar 8, 2014
is any simple way to apply the same code on both ActionListener and MouseListener, so that the same code is executed when the user either presses a JButton or presses Enter when a JTextField is focused.I know that I can define a method, while it is not preferred as I may use break; in my MouseListener.
A simple example:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TwoListener extends JFrame
{
[code]....
Although I can define a new method that prints out the three numbers, I have to add certain break; code in different cases. So I just wonder whether there is another way to do things like this.
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Mar 3, 2014
ActionPerformed and ActionListener on Netbeans...If I create a ComboBox on Netbeans using GUI design, then I right click over the Combobox I can find Events - Action - ActionPerformed... but I can't find ActionListener...
Are ActionPerformed and ActionListener the same?
or...
where is ActionListener on GUI Netbeans? Do I need to manualy write the ActionListener part?
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Mar 8, 2014
I need to add actionlistener to my code which allow the number 1 to 9 to function which are located in the nested for loop.
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class EX_7_2 extends JFrame {
public EX_7_2() {
setLayout(new BorderLayout(5, 10));
[Code] .....
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May 23, 2014
If you look at line 74 you will see my actionPerformed method where I want to switch the icon displayed on the JButton. I know I still have to add the images to the button however I am running into a few issues here.
In my next class it will be vital that I can decipher what each icon is display on the JButton.
Java Code: import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Screen implements ActionListener
[code]....
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Jul 26, 2014
I'm trying to acces my variable "cost" so when i press a button it prints the cost(for now) but the int value just prints 0
public class Holiday extends JFrame
{
private RoutinePanel routine; // A panel for routine charge checkboxes
private JPanel HolidayPanel; // A panel for non-routine charges
[Code].....
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Aug 13, 2014
I know that JMenu and JMenuItem is suppose to use action listeners but would you consider this implementation an exception?
menuAbout.addMouseListener (new MouseListener () {
@Override
public void mouseClicked (MouseEvent arg0) {
JOptionPane.showMessageDialog (null, "Server Tec Software System
}
@Override
public void mouseEntered (MouseEvent arg0) { }
@Override
public void mouseExited (MouseEvent arg0) { }
@Override
public void mousePressed (MouseEvent arg0) { }
@Override
public void mouseReleased (MouseEvent arg0) { }
});
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Feb 26, 2015
My task is to make a BorderLayout and when clicking a button it should say "Going Right!", "Going Up!" etc but I don't know how to create that:
Java Code:
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
[code]....
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Nov 28, 2014
Is there something special about this? I would think not, however all of the buttons in my application work except those with images.Here's an example of one:
Java Code: // Class #1
// All components defined as private initially, used in initComponents() later to build GUI
private JButton btnRock = new JButton();
/** Create the frame. **/
public GameView() {
initComponents(); // Initialize components
} // End of GameView Method
public void initComponents() {
// ROCK BUTTON
btnRock = (JButton) mainController.createIcon("rock");
btnRock.setForeground(new Color(0, 0, 0));
btnRock.setBounds(12, 34, 97, 67);
[code]....
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