How can I make it so that when I press enter in a JTextField it activates a specific JButton? What I mean is something along the lines of a web page form where you can press enter to activate the button in the form.
You should use an Action for the JButton:
Action sendAction = new AbstractAction("Send") {
public void actionPerformed(ActionEvent e) {
// do something
}
};
JButton button = new JButton(sendAction);
Then you can set the same action for a JTextField or even on a MenuItem if you want the same action to be available in the Menu:
JTextField textField = new JTextField();
textField.setAction(sendAction);
Something like this should work:
textField.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
button.requestFocusInWindow();
}
});
You can achieve this by adding the default behavior to the button, like this
cmdLogin.setDefaultCapable(true); // by default, this is true
this.getRootPane().setDefaultButton(cmdLogin); // here `this` is your parent container
I'd do something like the following:
textField.addKeyListener(
new KeyAdapter() {
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
button.doClick();
}
}
});
}
Related
So I have a Submit button with an ActionEvent that consists of around 50 lines of code. How would I assign the exact same ActionEvent for the JFrame as the Submit button whenever it detects the Enter key being pressed? This is what my Submit button's ActionEvent looks like
btnSubmit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// miscellaneous code that needs to be repeated for 'Enter' key press
}
});
What and where would the code for giving the JFrame the same ActionEvent as the Submit button go?
Start by taking a look at How to Use Root Panes and in particular JRootPane#setDefaultButton
When you have components which may consume the Enter key (like text fields), you might need to consider using the key bindings API
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0), "Enter.pressed");
am.put("Enter.pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
btnSubmit.doClick();
}
});
Now, about now, I might consider making an Action which be applied to both the JButton and key binding
Have a look at How to Use Key Bindings and How to Use Actions for more details
I don't know if there's a more correct swing way, but this should do the trick:
ActionListener listener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
//...
}
}
btnSubmit.addActionListener(listener);
btnEnter.addActionListener(listener);
One way to do this is to use the .doClick() method on the Submit button and create a KeyAdapter:
KeyAdapter Enter = new KeyAdapter(){
#Override
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_ENTER){
btnSubmit.doClick();
}
}
};
txtField1.addKeyListener(Enter);
txtField2.addKeyListener(Enter);
I created this little test program. It has 2 buttons and 2 labels. I want to know how I can use 2 buttons. So when I press button-1 then I change the text for text-1 and when I press button-2 then I change text for text-2. I just wanna get an idea of how I can use multiple buttons.
My code:
JLabel text1, text2;
JButton button1, button2;
public Game(String title) {
super(title);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
getContentPane().setLayout(new FlowLayout());
addComponents();
setSize(250, 250);
setResizable(false);
}
public void addComponents() {
text1 = new JLabel();
getContentPane().add(text1, text2);
text2 = new JLabel();
getContentPane().add(text2);
button1 = new JButton("Button");
getContentPane().add(button1);
button1.addActionListener(this);
button2 = new JButton("Button 2");
getContentPane().add(button2);
button2.addActionListener(this);
}
#Override
public void actionPerformed(ActionEvent e) {
}
I'm new to programming, so I would also like if someone could write some comments for the code. Just so I get an idea on how the code for multiple buttons work.
In your actionPerformed method you can get the source of the action
#Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == button1){
//Do Something
}else if(e.getSource() == button2){
//Do Something Else
}
There are various approaches to add listeners to buttons, here just a couple:
Inner
If you don't have to do much actions in each button you can add inner listener in each button
button1.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
// DO STUFF
}
});
Common Listener
If you have more than 2 buttons (i guess your app will be bigger) you can use your actionPerformed(ActionEvent e) and get source of the action
#Override
public void actionPerformed(ActionEvent e) {
JButton source = (JButton) e.getSource();
if(source.equals(button1)){
// DO STUFF
}
}
Use actionCommand to clarify
To clarify this approach I would reccommend to use JButton.setActionCommand(stringCommand) so after you can use a switch:
Declaring buttons:
button1.setActionCommand("command1");
button2.setActionCommand("command2");
In ActionListener::actionPerformed()
public void actionPerformed(ActionEvent e) {
String command = ((JButton) e.getSource()).getActionCommand();
switch (command) {
case "command1":
// DO STUFF FOR BUTTON 1
break;
case "command2":
// DO STUFF FOR BUTTON 2
break;
}
}
Using Java 8, its it much more concise to add ActionListeners:
button.addActionListener(ae -> System.out.println("foo"));
Using multiple statements:
button.addActionListener(ae -> {
System.out.println("foo");
System.out.println("bar");
});
You should not use setVisible(true) before the components are added.
There are a few ways to deal with more elements in an ActionEvent:
e.getSource() returns the object on which the event occurred. So, if button1 was pressed, e.getSource() will be the same as button1 (and e.getSource()==button1 will thus be true)
You can use separate classes for each ActionEvent. If you would add the ActionListener "Button1ActionEvent" [button1.addActionListener(new Button1ActionEvent());] you have to create this class, let it implement ActionListener and add the method actionPerformed as you had in your main class. Also, you can create a listener inside of the addActionListener-method [button1.addActionListener(new ActionListener() { // actionPerformed-method here });]
I'm building simple chat application with simple GUI, but a I have a problem assigning Enter key to Send button. Right now it is quite unpractical pressing Alt+Enter.
public void buildInterface() {
//some other components
btnSend = new JButton("Send");
btnExit = new JButton("Exit");
btnSearch=new JButton("Search");
btnSend.setMnemonic(KeyEvent.VK_ENTER);
JPanel box=new JPanel();
add(box, BorderLayout.SOUTH);
box.add(tfInput);
box.add(btnSend);
box.add(btnExit);
box.add(btnSearch);
}
When the button is focused, under most look and feels the Enter will activate the button.
You can, however, assign a button to be the "default" button for the window, which will be activated when the Enter key pressed, so long as the focused component does not consume it.
See How to Use Root Panes and JRootPane#setDefaultButton for more details
Add following code to your Util class
public static void bindKeyStroke(final JButton btn, String ks) {
final ActionListener[] alist = btn.getActionListeners();
if (alist.length != 0) {
AbstractAction action = new AbstractAction(btn.getText(), btn.getIcon()) {
#Override
public void actionPerformed(ActionEvent e) {
for (ActionListener al : alist) {
ActionEvent ae = new ActionEvent(e.getSource(), e.getID(), Action.ACCELERATOR_KEY);
al.actionPerformed(ae);
}
}
};
KeyStroke keyStroke = KeyStroke.getKeyStroke(ks);
btn.setAction(action);
btn.getActionMap().put(Action.ACCELERATOR_KEY, action);
btn.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(keyStroke, Action.ACCELERATOR_KEY);
}
}
Goto frame, dialog or panel constructor and add after initComponent();
Util.bindKeyStroke(<your button>, "alt enter");
Fix double action, in action performed
if (evt.getActionCommand().equals(Action.ACCELERATOR_KEY)) {
// Your send action here
}
I want to remove JButton when user click JButton.
I know that I should use remove method, but it did not work.
How can I do this?
Here is my code:
class Game implements ActionListener {
JFrame gameFrame;
JButton tmpButton;
JLabel tmpLabel1, tmpLabel2, tmpLabel3, tmpLabel4;
public void actionPerformed(ActionEvent e) {
gameFrame.remove(tmpLabel1);
gameFrame.getContentPane().validate();
return;
}
Game(String title) {
gameFrame = new JFrame(title);
gameFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gameFrame.setBounds(100, 100, 300, 500);
gameFrame.setResizable(false);
gameFrame.getContentPane().setLayout(null);
tmpLabel4 = new JLabel(new ImageIcon("./images/bomber.jpg"));
tmpLabel4.setSize(200, 200);
tmpLabel4.setLocation(50, 100);
tmpButton = new JButton("Play");
tmpButton.setSize(100, 50);
tmpButton.setLocation(100, 350);
tmpButton.addActionListener(this);
gameFrame.getContentPane().add(tmpLabel4);
gameFrame.getContentPane().add(tmpButton);
gameFrame.setVisible(true);
}
}
If hiding the button instead of removing works for your code then you can use:
public void actionPerformed(ActionEvent event){
tmpButton.setVisible(false);
}
for the button.But the button is just hidden not removed.
The simplest solution might be to...
Attach an ActionListener to the button, see How to Use Buttons, Check Boxes, and Radio Buttons and How to Write an Action Listeners for more details
When the ActionListener is clicked, extract the source of the event, JButton buttonThatWasClicked = (JButton)actionEvent.getSource()
Remove it from it's parent...
For example...
Container parent = buttonThatWasClicked.getParent();
parent.remove(buttonThatWasClicked);
parent.revaidate();
parent.repaint();
As some ideas...
First of all in your actionPerformed method you need to check that the button is clicked or not. And if the button is clicked, remove it. Here's how :
if(e.getSource() == tmpButton){
gameFrame.getContentPane().remove(tmpButton);
}
add this to your actionPerformed Method
don't add your button to jframe but add each component you want!
public void actionPerformed(ActionEvent event)
{
//gameFrame.getContentPane().add(tmpButton); -=> "Commented Area"
gameFrame.getContentPane().validate();
}
or hide your button like this
public void actionPerformed(ActionEvent event)
{
tmpButton.setVisible(false);
}
I have a JFrame with a Button that opens a different JFrame. But I want the button to only open the second frame once. Problem is, every time I click it I get a new instance of the frame. This must be a very common problem, since I'm following a book on how to create this GUI. I find it odd that the author didn't mention this "feature".
So how do I keep my button from opening multiple copies of the new frame?
Instead of letting the button create a new JFrame every time, make the second JFrame a member of the first JFrame, and only let the button call jframe2.setVisible(true);:
class JFrame1 {
JFrame2 jframe2=...;
JButton button=...;
JFrame1() {
...
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
jframe2.setVisible(true);
}
});
...
}
}
UPDATED!
try this:
JFrame frame2 = new JFrame(); // instance variable
...
//when button is clicked
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(!frame2.isVisible())
frame2.setVisible(true);
}
});
make sure you are handling the closing of all of the JFrames manually like this:
frame2.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
// handle closing the window
frame2.setVisible(false);
frame2.dispose();
}
});
instead of using the JFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
hope this helps.
You should keep a reference to the sub frame you open for first time. At second time you first check if you have a reference or not and then decide to create a new frame or to put the focus onto the existing open frame.
Example as answer to comment of OP (similar to other answer of #AlexanderTorstling, but not immediately creating the sub frame):
class MainFrame extends JFrame {
private JFrame subFrame = null;
MainFrame() {
...
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (subFrame == null) {
subFrame = new JFrame();
...
}
subFrame.setVisible(true);
}
});
}
}
This example has also the advantage to give you the possibility to close the subframe via a registered WindowAdapter if the main frame is closed.
please try this one
JFrame frame2 = new JFrame(); // instance variable
boolean secondWindowIsOpne = false;
...
//when button is clicked
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(secondWindowIsOpne == false){
frame2.setVisible(true);
secondWindowIsOpne = true;
}
else{
System.out.println("This Window is already running");
}
});
make sure you are handling the closing of all of the JFrames manually like this:
frame2.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
// handle closing the window
secondWindowIsOpne = false;
frame2.setVisible(false);
frame2.dispose();
}
});