I want to make a program with these goals:
1) Make a JButton
2) Attach the button to a key (The "A" Key) using KeyBindings
3) Execute some code when "A" is clicked
Here is the code I have so far:
// Imports
Public class Test{
JButton button = new JButton();
//...
Test(){
button.getInputMap().put(KeyStroke.getKeyStroke("A"), "Pressed");
//...
}
// Where do I add the code that responds when button is pressed?
}
Now where do I add the code that I want it to execute when the button is pressed?
Two ways I can think of:
Have JButton and and Key Bindings share the same AbstractAction, or perhaps better
Simply call doClick() on the button from the key binding.
KeyBindingEg.java
import java.awt.event.*;
import javax.swing.*;
public class KeyBindingEg extends JPanel {
private JButton btnA = new JButton();
public KeyBindingEg() {
Action btnAction = new ActionOne("A");
Action keyBindingAction = new ActionTwo();
int condition = JLabel.WHEN_IN_FOCUSED_WINDOW;
InputMap inputmap = btnA.getInputMap(condition);
ActionMap actionmap = btnA.getActionMap();
final String aKeyPressed = "a key pressed";
inputmap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), aKeyPressed );
actionmap.put(aKeyPressed, keyBindingAction);
// actionmap.put(aKeyPressed, btnAction); // one or the other, your choice
btnA.setAction(btnAction);
add(btnA);
}
private class ActionOne extends AbstractAction {
public ActionOne(String text) {
super(text);
}
#Override
public void actionPerformed(ActionEvent e) {
sharedMethod();
}
}
private class ActionTwo extends AbstractAction {
#Override
public void actionPerformed(ActionEvent e) {
btnA.doClick();
}
}
private void sharedMethod() {
System.out.println("Method called by either key bindings or action listener");
}
private static void createAndShowGui() {
JFrame frame = new JFrame("KeyBindingEg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new KeyBindingEg());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
you need to add an action listener, specificaly for actionPerformed. declare this somewhere inside your constructor:
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.KeyStroke;
public class Main {
public static void main(String[] argv) throws Exception {
JButton component = new JButton();
MyAction action = new MyAction();
component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("F2"),
action.getValue(Action.NAME));
}
}
class MyAction extends AbstractAction {
public MyAction() {
super("my action");
}
public void actionPerformed(ActionEvent e) {
//Here goes the code where the button does something
System.out.println("hi");//In this case we print hi
}
}
In this example if we press F2 it will be the equivalent of pressing the button.
Related
I have two classes that implement KeyListener and FocusListener interfaces. Neither works, but if I don't add the JButton by commenting or removing this: add(whiteJButton), then they do work. Could someone explain to me why this happens? Thanks in advance.
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class JFrames {
public static void main(String[] args) {
JFrame myJFrame = new JFrame("MyJFrame");
myJFrame.setBounds(400, 400, 500, 500);
myJFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
MyJPanel myJPanel = new MyJPanel();
myJFrame.add(myJPanel);
// Doesn't work
myJFrame.addKeyListener(new MyKeyListener());
// Doesn't work
myJFrame.addFocusListener(new MyFocusListener());
myJFrame.setVisible(true);
}
static class MyJPanel extends JPanel {
public MyJPanel() {
JButton whiteJButton = new JButton("WHITE");
add(whiteJButton);
whiteJButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setBackground(Color.WHITE);
}
});
}
}
}
class MyKeyListener implements KeyListener {
#Override
public void keyTyped(KeyEvent e) {
System.out.println("keyTyped: " + e.getKeyChar());
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println("keyPressed: " + e.getKeyChar());
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println("keyReleased: " + e.getKeyChar());
}
}
class MyFocusListener implements FocusListener {
#Override
public void focusGained(FocusEvent e) {
System.out.println("focusGained");
}
#Override
public void focusLost(FocusEvent e) {
System.out.println("focusLost");
}
}
The problem is that the button steals focus from the JFrame, preventing the focus listener from working (focus is already gone). Some solutions if you absolutely need to use a KeyListener are kludges, including making the JButton not focusable: whiteJButton.setFocusable(false);, but if you do this, you need to do this for all components added. And yes you can request focus as the other answer suggests, but it should be requestFocusInWindw(), not requestFocus() (many similar questions explain why this is so). And if you do this and the components are still focusable, then the whole thing breaks down if a component gains focus -- not good.
Better (as per comments) is to use Key Bindings which don't require focus to work if you use the correct InputMap. Note that key bindings is how Swing itself traps keystrokes for components, so using this would follow with the Swing general structure and contracts. The problem with Key Bindings is that you have to bind each key that you wish to trap, but you can use for loops to assist with this.
Another solution is to use a KeyEventDispatcher to the keyboard focus manager:
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
// code goes here
return false;
}
});
Example using Key Bindings:
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class KeyboardFun extends JPanel {
private InputMap inputMap = getInputMap(WHEN_IN_FOCUSED_WINDOW);
private ActionMap actionMap = getActionMap();
public KeyboardFun() {
setBorder(BorderFactory.createEmptyBorder(3, 3, 3, 3));
setLayout(new GridLayout(0, 8, 3, 3));
for (char c = 'A'; c <= 'Z'; c++) {
final String text = String.valueOf(c);
JButton button = new JButton(text);
button.addActionListener(e -> {System.out.println("Key pressed: " + text);});
add(button);
setBinding(c, button);
}
}
private void setBinding(char c, final JButton button) {
KeyStroke keyStroke = KeyStroke.getKeyStroke(Character.toLowerCase(c));
inputMap.put(keyStroke, keyStroke.toString());
actionMap.put(keyStroke.toString(), new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
button.doClick();
}
});
}
private static void createAndShowGui() {
KeyboardFun mainPanel = new KeyboardFun();
JFrame frame = new JFrame("KeyboardFun");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
You must focus the object that you add listener, try add listener to "myJFrame". You can't focus JPanel.
Your JPanel is probably isn't focusable at start and your JButton gets Focus.
So you can also add this codes to "myJPanel" :
setFocusable(true);
requestFocusInWindow();
a basic problem that i can't figure out, tried a lot of things and can't get it to work, i need to be able to get the value/text of the variable
String input;
so that i can use it again in a different class in order to do an if statement based upon the result
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
public class pInterface extends JFrame {
String input;
private JTextField item1;
public pInterface() {
super("PAnnalyser");
setLayout(new FlowLayout());
item1 = new JTextField("enter text here", 10);
add(item1);
myhandler handler = new myhandler();
item1.addActionListener(handler);
System.out.println();
}
public class myhandler implements ActionListener {
// class that is going to handle the events
public void actionPerformed(ActionEvent event) {
// set the variable equal to empty
if (event.getSource() == item1)// find value in box number 1
input = String.format("%s", event.getActionCommand());
}
public String userValue(String input) {
return input;
}
}
}
You could display the window as a modal JDialog, not a JFrame and place the obtained String into a private field that can be accessed via a getter method. Then the calling code can easily obtain the String and use it. Note that there's no need for a separate String field, which you've called "input", since we can easily and simply extract a String directly from the JTextField (in our "getter" method).
For example:
import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import javax.swing.*;
import javax.swing.text.JTextComponent;
public class TestPInterface {
#SuppressWarnings("serial")
private static void createAndShowGui() {
final JFrame frame = new JFrame("TestPInterface");
// JDialog to hold our JPanel
final JDialog pInterestDialog = new JDialog(frame, "PInterest",
ModalityType.APPLICATION_MODAL);
final MyPInterface myPInterface = new MyPInterface();
// add JPanel to dialog
pInterestDialog.add(myPInterface);
pInterestDialog.pack();
pInterestDialog.setLocationByPlatform(true);
final JTextField textField = new JTextField(10);
textField.setEditable(false);
textField.setFocusable(false);
JPanel mainPanel = new JPanel();
mainPanel.add(textField);
mainPanel.add(new JButton(new AbstractAction("Get Input") {
#Override
public void actionPerformed(ActionEvent e) {
// show dialog
pInterestDialog.setVisible(true);
// dialog has returned, and so now extract Text
textField.setText(myPInterface.getText());
}
}));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
// by making the class a JPanel, you can put it anywhere you want
// in a JFrame, a JDialog, a JOptionPane, another JPanel
#SuppressWarnings("serial")
class MyPInterface extends JPanel {
// no need for a String field since we can
// get our Strings directly from the JTextField
private JTextField textField = new JTextField(10);
public MyPInterface() {
textField.addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent e) {
JTextComponent textComp = (JTextComponent) e.getSource();
textComp.selectAll();
}
});
add(new JLabel("Enter Text Here:"));
add(textField);
textField.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Window win = (Window) SwingUtilities.getWindowAncestor(MyPInterface.this);
win.dispose();
}
});
}
public String getText() {
return textField.getText();
}
}
A Good way of doing this is use Callback mechanism.
I have already posted an answer in the same context.
Please find it here JFrame in separate class, what about the ActionListener?.
Your method is a bit confusing:
public String userValue(String input) {
return input;
}
I guess you want to do something like this:
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
Also your JFrame is not visible yet. Set the visibility like this setVisible(true)
So I've built a very basic Web browser - I'm trying desperately to remove the contents of the address bar when a user clicks on it (JTextField) this appears with some text in as default. Any advice is appreciated.
Have a great day!
MY CODE
import java.awt.*;
import java.awt.event.*;
import java.io.IOException;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class Web_Browser extends JFrame {
private final JTextField addressBar;
private final JEditorPane display;
// Constructor
public Web_Browser() {
super("Web Browser");
addressBar = new JTextField("Click & Type Web Address e.g. http://www.google.com");
addressBar.addActionListener(
new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
loadGo(event.getActionCommand());
}
}
);
add(addressBar, BorderLayout.NORTH);
display = new JEditorPane();
display.setEditable(false);
display.addHyperlinkListener(
new HyperlinkListener(){
#Override
public void hyperlinkUpdate(HyperlinkEvent event){
if(event.getEventType()==HyperlinkEvent.EventType.ACTIVATED){
loadGo(event.getURL().toString());
}
}
}
);
add(new JScrollPane(display), BorderLayout.CENTER);
setSize(500,300);
setVisible(true);
}
// loadGo to sisplay on the screen
private void loadGo(String userText) {
try{
display.setPage(userText);
addressBar.setText(userText);
}catch(IOException e){
System.out.println("Invalid URL, try again");
}
}
}
Use a FocusListener. On focusGained, select all.
addressBar.addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent e) {
JTextComponent textComponent = (JTextComponent) e.getSource();
textComponent.selectAll();
}
});
For example:
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import javax.swing.*;
import javax.swing.text.JTextComponent;
#SuppressWarnings("serial")
public class FocusExample extends JPanel {
private static final int TF_COUNT = 5;
private JTextField[] textFields = new JTextField[TF_COUNT];
public FocusExample() {
for (int i = 0; i < textFields.length; i++) {
textFields[i] = new JTextField("Foo " + (i + 1), 10);
textFields[i].addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent e) {
JTextComponent textComponent = (JTextComponent) e.getSource();
textComponent.selectAll();
}
});
add(textFields[i]);
}
}
private static void createAndShowGui() {
FocusExample mainPanel = new FocusExample();
JFrame frame = new JFrame("FocusExample");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
This gives the user the option of leaving the previous text in place, of adding to the previous text, or of simply over-writing it by typing.
new JTextField("Click & Type Web Address e.g. http://www.google.com");
Maybe you want the Text Prompt, which doesn't actually store any text in the text field. It just gives the user a hint what the text field is for.
This is beneficial so that you don't generate DocumentEvents etc., since you are not actually changing the Document.
Add a mouseListener instead of your actionListener method.
addressBar.addMouseListener(new MouseAdapter(){
#Override
public void mouseClicked(MouseEvent e){
addressBar.setText("");
}
How can I assign two buttons to share the same class for handling events in Java/swing?
For example, I have this:
private class BtnEvtHandler implements ActionListener {
private int counter=10;
public void actionPerformed(ActionEvent e) {
gs.setX(counter);
gs.repaint();
counter=counter+10;
}
public void actionPerformed(ActionEvent e) {
//action for move button
}
}
JButton jumpBtn= new JButton("JUMP");
BtnEvtHandler okButtonHandler= new BtnEvtHandler();
(jumpBtn).addActionListener(okButtonHandler);
menuPanel.add(jumpBtn);
Now I want to add another button as below which can have the same class as event handler but dispatches to different actionPerformed as mentioned in above code.
JButton moveBtn= new JButton("MOVE");
menuPanel.add(moveBtn);
(moveBtn).addActionListener(okButtonHandler);
You can't reuse one ActionListener and expect it to call a different method depending on the button you attach it to. The contract of ActionListener has one method that gets called. But you can check the source of the event and have flow control based on that. Here's an example:
package com.sandbox;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
public class SwingSandbox {
public static void main(String[] args) throws IOException {
JFrame frame = buildFrame();
JPanel pane = new JPanel();
MyActionListener myActionListener = new MyActionListener();
JButton button1 = new JButton("Button1");
button1.addActionListener(myActionListener);
pane.add(button1);
JButton button2 = new JButton("Button2");
button2.addActionListener(myActionListener);
pane.add(button2);
frame.add(pane);
}
private static JFrame buildFrame() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setSize(200, 200);
frame.setVisible(true);
return frame;
}
private static class MyActionListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
JButton source = (JButton) e.getSource();
if ("Button1".equals(source.getText())) {
System.out.println("You clicked button 1");
} else {
System.out.println("You clicked button 2");
}
}
}
}
Please have a look at the following code
Main.Java
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class Main extends JFrame
{
private JButton ok;
public Main()
{
ok = new JButton("OK");
ok.addActionListener(new ButtonAction());
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
panel.add(ok);
getContentPane().add(panel,"South");
this.setVisible(true);
this.setSize(new Dimension(200,200));
this.validate();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[]args)
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
new Main();
}
catch(Exception e)
{
}
}
private class ButtonAction implements ActionListener
{
public void actionPerformed(ActionEvent ae)
{
Dialog d = new Dialog();
d.setVisible(true);
}
}
}
Dialog.java
import java.awt.Event;
import java.awt.*;
import javax.swing.*;
public class Dialog extends JDialog
{
private JButton done;
public Dialog()
{
done = new JButton("Done");
this.add(done);
this.setSize(new Dimension(400,200));
}
}
In here, I want to "attach" the Dialog form to the main form. Which means, when I click the OK button in Main.Java, Dialog form will get attached to the right side of the main form. So, when I move the main form, the dialog also get moved. However, dialog form should be independent, which means, when I click "x" button in dialog form, only that form exists, not the main form.
How can I attach this dialog form, to the right side of the main form, when the button is clicked? Please help!
The answer is not MouseListener, but it is ComponentListener. I managed to do it with using that listener's "componentMoved()" method.
Main.java
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class Main extends JFrame implements ComponentListener, ActionListener
{
private JButton ok;
private Dialog dialog;
public Main()
{
ok = new JButton("OK");
ok.addActionListener(this);
dialog = new Dialog();
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
panel.add(ok);
getContentPane().add(panel,"South");
this.addComponentListener(this);
this.setVisible(true);
this.setSize(new Dimension(200,200));
this.validate();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[]args)
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
new Main();
}
catch(Exception e){}
}
public void actionPerformed(ActionEvent ae)
{
dialog.setVisible(true);
}
#Override
public void componentHidden(ComponentEvent arg0) {}
#Override
public void componentMoved(ComponentEvent arg0)
{
int x = this.getX() + this.getWidth();
int y = this.getY();
dialog.setDialogLocation(x, y);
}
#Override
public void componentResized(ComponentEvent arg0) {}
#Override
public void componentShown(ComponentEvent arg0) {}
}
Dialog.java
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JDialog;
public class Dialog extends JDialog
{
private JButton done;
public Dialog()
{
done = new JButton("Done");
this.add(done);
this.setSize(new Dimension(400,200));
}
public void setDialogLocation(int x, int y)
{
this.setLocation(x, y);
}
}
I'm not aware of any built-in function that you can just say "dialog.moveWithThisOtherWindow(otherWindow)" or some such and it just happens. You would have to write code to do this yourself.
Create a mouse listener or mouse adapter on the parent form. In the "mouse moved" event in the mouse listener, move the child form. Of course the parent would have to have a handle to the child. Depending how you create the windows, you may need some sort of "register" function that the child can call to identify himself to the parent.