EXIT_ON_CLOSE variable error

[orgil khatanbaatar]

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.Icon;
import javax.swing.ImageIcon;

public class tuna4 extends JFrame{

public static void main(String args[]){
tuna4 obj=new tuna4();
obj.setDefaultCloseOperation(JFrame.EXIT_ON_CL0SE);
obj.setSize(200,300);
obj.setVisible(true);
}

private JButton reg=null;
private JButton custom=null;

public tuna4(){
super("this is title");
setLayout(new FlowLayout());
reg=new JButton("reg button");
add(reg);
Icon b=new ImageIcon(getClass().getResource("se.bmp"));
Icon x=new ImageIcon(getClass().getResource("P6220020.jpg"));
custom=new JButton("custom",b);
custom.setRolloverIcon(x);
add(custom);

thehandler handler=new thehandler();
reg.addActionListener(handler);
custom.addActionListener(handler);}

private class thehandler implements ActionListener{
public void actionPerformed(ActionEvent event){
JOptionPane.showMessageDialog(null,String.format(" %s",event.getActionCommand()));}}}

why is it giving error : "Can not find the symbol EXIT_ON_CLOSE variable"?

[Matthew Brown]

Because EXIT_ON_CLOSE doesn't exist in the JFrame class. It's in WindowConstants. Look at the Javadocs for the setDefaultCloseOperation method.

[orgil khatanbaatar]

Matthew Brown wrote:Because EXIT_ON_CLOSE doesn't exist in the JFrame class. It's in WindowConstants. Look at the Javadocs for the setDefaultCloseOperation method.

No fair. but other codes worked fine so far. I will give an example.

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
//import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class tuna3 extends JFrame{
JPasswordField item=null;

public tuna3(){
item=new JPasswordField("orgil");
add(item);
thehandler handle=new thehandler();
setLayout(new FlowLayout());
item.addActionListener(handle);
}

private class thehandler implements ActionListener{

public void actionPerformed(ActionEvent event){
String string="";
if(event.getSource()==item)
string=String.format("field 1: %s",event.getActionCommand());
JOptionPane.showMessageDialog(null,string);}
}
 
public static void main(String []args)
{tuna3 obj=new tuna3();
obj.setSize(200,150);
obj.setVisible(true);
obj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}
}

[Darryl Burke]

Matthew Brown wrote:Because EXIT_ON_CLOSE doesn't exist in the JFrame class. It's in WindowConstants.

Um, JFrame implements WindowConstants.

[Matthew Brown]

Good point . Didn't think that through, and was looking for a simple answer. In that case it's a little strange...

Ah, got it. It should be JFrame.EXIT_ON_CLOSE, not JFrame.EXIT_ON_CL0SE. Spot the difference? Convert it to lower case and it's more obvious.

[Darryl Burke]

orgil , your code doesn't follow the coding conventions and is extremely difficult to read. It's in your own interest to make the code easily readable, as that will get you more readers and quicker/better responses.

You have a typo in EXIT_ON_CL0SE. Look carefully at these two characters: O 0 -- see the difference?

Here's your code with the typo corrected and with class names and indents that conform to convention.

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.Icon;
import javax.swing.ImageIcon;

public class Tuna4 extends JFrame {

  public static void main(String args[]) {
    Tuna4 obj = new Tuna4();
    obj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    obj.setSize(200, 300);
    obj.setVisible(true);
  }
  private JButton reg = null;
  private JButton custom = null;

  public Tuna4() {
    super("this is title");
    setLayout(new FlowLayout());
    reg = new JButton("reg button");
    add(reg);
    Icon b = new ImageIcon(getClass().getResource("se.bmp"));
    Icon x = new ImageIcon(getClass().getResource("P6220020.jpg"));
    custom = new JButton("custom", b);
    custom.setRolloverIcon(x);
    add(custom);

    TheHandler handler = new TheHandler();
    reg.addActionListener(handler);
    custom.addActionListener(handler);
  }

  private class TheHandler implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent event) {
      JOptionPane.showMessageDialog(null, String.format(" %s", event.getActionCommand()));
    }
  }
}

[orgil khatanbaatar]

thank you awesome guys getting tiny error for me. Sorry for inconvenience of coding!