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Thread: Selly Mistake

  1. #1
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    Default Selly Mistake

    Hi

    As a review, I wrote the following code to implement Java Applet. The problems is when I press the button, the label does not change. I think the problem with "static" that I declared before each declaration of components.

    Java Code:
    import java.awt.Container;
    import java.awt.FlowLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    
    import javax.swing.*;
    
    public class Jframe implements ActionListener{
    	
    	public static JFrame frame = new JFrame("FrameDemo");
    	public static JLabel lbl = new JLabel("Hello .. Press Enter");
    	public static JButton button = new JButton("Press");
    	
    	public static void main(String[] args){
    		
    		frame.setSize(400, 150);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setVisible(true);
    		
    		Container content = frame.getContentPane();
    	    content.setLayout(new FlowLayout()); 
    	   
    	    content.add(lbl);
    	    
    	    content.add(button);
    	       
    	    
    	}
    	
    	public Jframe(){
    		button.addActionListener(this);	 
    	}
    
    	public void actionPerformed(ActionEvent arg0) {
    		if (arg0.getSource()==button){
    		lbl.setText("Welcome");
    		}
    	}
    }
    Thank you.

  2. #2
    JosAH's Avatar
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    There's a difference between a JFrame and a Jframe ...

    edit: darn, those names are misleading ...

    kind regards,

    Jos
    Last edited by JosAH; 04-19-2011 at 03:17 PM.
    cenosillicaphobia: the fear for an empty beer glass

  3. #3
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    Default

    It didn't work :(

    Thank you for your helping

  4. #4
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    Quote Originally Posted by ŖΫ ỏ Ңόρę View Post
    It didn't work :(

    Thank you for your helping
    Stick a few System.out.printlns( ... ) in your actionPerformed( ... ) method and see if it is called.

    kind regards,

    Jos

    ps. and please change the class name, it's making me dizzy.
    cenosillicaphobia: the fear for an empty beer glass

  5. #5
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    Java Code:
    import java.awt.Container;
    import java.awt.FlowLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    
    import javax.swing.*;
    
    public class TryJframe implements ActionListener{
    	
    	public static JFrame frame = new JFrame("FrameDemo");
    	public static JLabel lbl = new JLabel("Hello .. Press Enter");
    	public static JButton button = new JButton("Press");
    	
    	public static void main(String[] args){
    		
    		frame.setSize(400, 150);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setVisible(true);
    		
    		Container content = frame.getContentPane();
    	    content.setLayout(new FlowLayout()); 
    	   
    	    content.add(lbl);
    	    
    	    content.add(button);
    	       
    	    
    	}
    	
    	public TryJframe(){
    		button.addActionListener(this);	 
    	}
    
    	public void actionPerformed(ActionEvent arg0) {
    		if (arg0.getSource()==button){
    		lbl.setText("Welcome");
    		}
    	}
    }
    I did what you told me but nothing has changed. It seems the problem with the button.

  6. #6
    JosAH's Avatar
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    Quote Originally Posted by ŖΫ ỏ Ңόρę View Post
    Java Code:
    import java.awt.Container;
    import java.awt.FlowLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    
    import javax.swing.*;
    
    public class TryJframe implements ActionListener{
    	
    	public static JFrame frame = new JFrame("FrameDemo");
    	public static JLabel lbl = new JLabel("Hello .. Press Enter");
    	public static JButton button = new JButton("Press");
    	
    	public static void main(String[] args){
    		
    		frame.setSize(400, 150);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setVisible(true);
    		
    		Container content = frame.getContentPane();
    	    content.setLayout(new FlowLayout()); 
    	   
    	    content.add(lbl);
    	    
    	    content.add(button);
    	       
    	    
    	}
    	
    	public TryJframe(){
    		button.addActionListener(this);	 
    	}
    
    	public void actionPerformed(ActionEvent arg0) {
    		if (arg0.getSource()==button){
    		lbl.setText("Welcome");
    		}
    	}
    }
    I did what you told me but nothing has changed. It seems the problem with the button.
    You didn't add a System.out.println("whatever ...") to your actionPerformed( ... ) method. You should at least see it output the String when you press that button.

    kind regards,

    Jos
    cenosillicaphobia: the fear for an empty beer glass

  7. #7
    JosAH's Avatar
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    Got it: you didn't create a new TryJFrame() in your main method so there is no ActionListener attached to your button ...

    kind regards,

    Jos
    cenosillicaphobia: the fear for an empty beer glass

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