I have a program with a JFrame that I use a WindowListener to close the program with. I use the following method to prompt a message about saving changes made in the program:
public void windowClosing(WindowEvent e) {
if (condition) {
System.exit(0);
}
However, when I press cmd + Q, my program will quit without me having the option of saving. Is there a smart way to make sure that I can have a condition before I close my program regardless if I close it through the window X or through my keyboard short commands? Or do I need to create a KeyEvent for this?
You need to change the DefaultCloseOperation on JFrame and then dispose() the frame on windowClosing event (or System.exit(0) like you show above). Here is a simple working example:
JFrame f = new JFrame();
f.setPreferredSize(new Dimension(300, 300));
f.pack();
f.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
f.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent we) {
if (condition) {
f.dispose();
}
}
});
f.setVisible(true);
This way all closing operation will use your condition.
However, when I press cmd + Q,
I believe that is a keystroke you enter from the command line?
If so you might be able to use addShutDownHook(...) method found in the Runtime class.
Related
I have a program with a GUI that needs to open a separate window and wait for the user to select and option, then continue. I figure I should be doing this with the wait() and notify() methods, but I'm still trying to figure out exactly how to use those. A complicating factor is that things seem to work differently when the second window is created in an actionPerformed() method, which it needs to be.
Here's how I think it should be done here, apparently it is not quite right...
This should create a window with a button, when the button is pressed, another window with a button should be created, and when that button is pressed, the program should print "End".
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class WtfExample {
public static void main(String[] args) {
JFrame jf = new JFrame();
JButton butt = new JButton("Button");
butt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
WtfExample we = new WtfExample();
we.display();
}
});
jf.getContentPane().add(butt);
jf.setSize(new Dimension(1000, 500));
jf.setVisible(true);
System.out.println("End");
}
public synchronized void display() {
JFrame jf = new JFrame();
JButton butt = new JButton("Button");
butt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
synchronized(WtfExample.this) {
WtfExample.this.notifyAll();
}
}
});
jf.getContentPane().add(butt);
jf.setSize(new Dimension(1000, 500));
jf.setVisible(true);
while(true) {
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
break;
}
}
}
}
edit- I wasn't clear enough in one thing- the second window that's opened is blank, like its components were never added to it. That's the case whether it's a frame or dialog, but that only happens if the window is created from the actionPerformed method.
No, you should just be using a JDialog.
You need a modal dialog window. Here's a tutorial on dialogs. It is easier to use JOptionPane for the simple cases.
A Dialog can be modal. When a modal Dialog is visible, it blocks user input to all other windows in the program.
As the other two answers suggest you need a modal JDialog. You do not need to deal with any Thread classes. The JDialog window will deal with the giving you control back once the user input is handled. There are a few ways you can set the dialog box modal. Here are two examples.
new JDialog(Dialog owner, boolean modal)
or
new JDialog(Dialog owner, String title, boolean modal)
You could also do something like this:
JDialog dialog = new JDialog(owner);
dialog.setModal(true);
I think this is a pretty good article about modality in JAVA.
void terminate() {}
protected JFrame frame = new JFrame();
How can I get frame to run the terminate function when I press the close button?
Edit: I tried to run this, but for some reason it doesn't print test (however, the program closes). Does anyone have an idea what could be the problem?
frame.addWindowListener(new WindowAdapter() {
public void WindowClosing(WindowEvent e) {
System.out.println("test");
frame.dispose();
}
});
You can use addWindowListener:
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
// call terminate
}
});
See void windowClosing(WindowEvent e) and Class WindowAdapter too.
Not only do you have to add the window listener, you have to set the default close operation to do nothing on close. This allows your code to execute.
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent event) {
exitProcedure();
}
});
Finally, you have to call System exit to actually stop your program from running.
public void exitProcedure() {
frame.dispose();
System.exit(0);
}
Frame.dispose() method does not terminate the program. To terminate the program you need to call System.exit(0) method
If you want to terminate your program after the JFrame is closed, you have to set the default close operation on your JFrame.
In your constructor of your JFrame write:
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
If you just want to call a method when the window is closed and not terminate the whole program, than go with the answer of Maroun.
I want to call a method confirmExit() when the red close button of the title bar of a JFrame is clicked.
How can I capture that event?
I'd also like to prevent the window from closing if the user chooses not to proceed.
import javax.swing.JOptionPane;
import javax.swing.JFrame;
/*Some piece of code*/
frame.addWindowListener(new java.awt.event.WindowAdapter() {
#Override
public void windowClosing(java.awt.event.WindowEvent windowEvent) {
if (JOptionPane.showConfirmDialog(frame,
"Are you sure you want to close this window?", "Close Window?",
JOptionPane.YES_NO_OPTION,
JOptionPane.QUESTION_MESSAGE) == JOptionPane.YES_OPTION){
System.exit(0);
}
}
});
If you also want to prevent the window from closing unless the user chooses 'Yes', you can add:
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
Override windowClosing Method.
public void windowClosing(WindowEvent e)
It is invoked when a window is in the process of being closed. The close operation can be overridden at this point.
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
also works. First create a JFrame called frame, then add this code underneath.
This may work:
jdialog.addWindowListener(new WindowAdapter() {
public void windowClosed(WindowEvent e) {
System.out.println("jdialog window closed event received");
}
public void windowClosing(WindowEvent e) {
System.out.println("jdialog window closing event received");
}
});
Source: https://alvinalexander.com/java/jdialog-close-closing-event
This is what I put as a menu option where I made a button on a JFrame to display another JFrame. I wanted only the new frame to be visible, and not to destroy the one behind it. I initially hid the first JFrame, while the new one became visible. Upon closing of the new JFrame, I disposed of it followed by an action of making the old one visible again.
Note: The following code expands off of Ravinda's answer and ng is a JButton:
ng.addActionListener((ActionEvent e) -> {
setVisible(false);
JFrame j = new JFrame("NAME");
j.setVisible(true);
j.addWindowListener(new java.awt.event.WindowAdapter() {
#Override
public void windowClosing(java.awt.event.WindowEvent windowEvent) {
setVisible(true);
}
});
});
Try this:
setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
It will work.
I have a problem with my application where the user will open more than one window at a time. And i have added dispose() method to call on closing the window. Now i should keep at-least one window open all the time so that the application does not hides without closed fully. If you don't understand read the following scenario:
I have window A and window B opened at the same time. Now i can close either window A or Window B but not both. In other words window B should be allowed to close only if window A is opened and vice versa. How do i do this in swing ??
A simple kind-of windowManger is not really tricky, all you need is
WindowListener which keeps tracks of the Windows it's listening to
a defined place to create the windows and register the the listener
make the windows do-nothing-on-close and make the listener responsible for the decision of whether to close or not (will do so for all except the last)
Some snippet:
// the listener (aka: WindowManager)
WindowListener l = new WindowAdapter() {
List<Window> windows = new ArrayList<Window>();
#Override
public void windowOpened(WindowEvent e) {
windows.add(e.getWindow());
}
#Override
public void windowClosing(WindowEvent e) {
if (windows.size() > 1) {
windows.remove(e.getWindow());
e.getWindow().dispose();
}
}
};
// create the first frame
JFrame frame = createFrame(l);
frame.setVisible(true);
// a method to create a new window, config and add the listener
int counter = 0;
private JFrame createFrame(final WindowListener l) {
Action action = new AbstractAction("open new frame: " + counter) {
#Override
public void actionPerformed(ActionEvent e) {
JFrame frame = createFrame(l);
frame.setVisible(true);
}
};
JFrame frame = new JFrame("someFrame " + counter++);
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.add(new JButton(action));
frame.addWindowListener(l);
frame.pack();
frame.setLocation(counter * 20, counter * 10);
return frame;
}
Just a possible approach...
Create a class, call it WindowManager, that manages creation and disposal of windows.
It could for example retain the count of the windows currently open, and allow a dispose operation only if there are more than one windows "alive", otherwise show a confirm message with JOptionPane telling the user "Really close? That would terminate the application." or something like that.
The "tricky" part is that you have to do this kind of window-related operations throughout the WindowManager, otherwise everything would screw up.
Dunno if Swing has something like this built-in, I've never seen such a scenario.
simply check if the other window is open before closing with window.isVisible();
I have a program with a GUI that needs to open a separate window and wait for the user to select and option, then continue. I figure I should be doing this with the wait() and notify() methods, but I'm still trying to figure out exactly how to use those. A complicating factor is that things seem to work differently when the second window is created in an actionPerformed() method, which it needs to be.
Here's how I think it should be done here, apparently it is not quite right...
This should create a window with a button, when the button is pressed, another window with a button should be created, and when that button is pressed, the program should print "End".
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class WtfExample {
public static void main(String[] args) {
JFrame jf = new JFrame();
JButton butt = new JButton("Button");
butt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
WtfExample we = new WtfExample();
we.display();
}
});
jf.getContentPane().add(butt);
jf.setSize(new Dimension(1000, 500));
jf.setVisible(true);
System.out.println("End");
}
public synchronized void display() {
JFrame jf = new JFrame();
JButton butt = new JButton("Button");
butt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
synchronized(WtfExample.this) {
WtfExample.this.notifyAll();
}
}
});
jf.getContentPane().add(butt);
jf.setSize(new Dimension(1000, 500));
jf.setVisible(true);
while(true) {
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
break;
}
}
}
}
edit- I wasn't clear enough in one thing- the second window that's opened is blank, like its components were never added to it. That's the case whether it's a frame or dialog, but that only happens if the window is created from the actionPerformed method.
No, you should just be using a JDialog.
You need a modal dialog window. Here's a tutorial on dialogs. It is easier to use JOptionPane for the simple cases.
A Dialog can be modal. When a modal Dialog is visible, it blocks user input to all other windows in the program.
As the other two answers suggest you need a modal JDialog. You do not need to deal with any Thread classes. The JDialog window will deal with the giving you control back once the user input is handled. There are a few ways you can set the dialog box modal. Here are two examples.
new JDialog(Dialog owner, boolean modal)
or
new JDialog(Dialog owner, String title, boolean modal)
You could also do something like this:
JDialog dialog = new JDialog(owner);
dialog.setModal(true);
I think this is a pretty good article about modality in JAVA.