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Thread: Jframe title setting question

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    Default Jframe title setting question

    i was wondering what the difference between these 2 to set the title of a jframe?

    super("Main Frame");

    and

    setTitle("Main Frame");


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    Default Re: Jframe title setting question

    tl;dr version: there is no real difference. One calls the constructor, another calls the setTitle() method. They both go up to Frame, which sets its title variable.

    Look at the code for JFrame (the source is available):

       public JFrame(String title) throws HeadlessException {
            super(title);
            frameInit();
        }
     
       //there is no setTitle() method in JFrame

    And for Frame:
        public Frame(String title) throws HeadlessException {
            init(title, null);
        }
     
        private void init(String title, GraphicsConfiguration gc) {
            this.title = title;
            SunToolkit.checkAndSetPolicy(this, false);
        }
     
        public void setTitle(String title) {
            String oldTitle = this.title;
            if (title == null) {
                title = "";
            }
     
     
            synchronized(this) {
                this.title = title;
                FramePeer peer = (FramePeer)this.peer;
                if (peer != null) {
                    peer.setTitle(title);
                }
            }
            firePropertyChange("title", oldTitle, title);
        }

    Does that answer your question?
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  3. The Following 2 Users Say Thank You to KevinWorkman For This Useful Post:

    derekxec (June 15th, 2011), william (June 16th, 2011)

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    Default Re: Jframe title setting question

    that does thank you very much...the book im reading says you can set either way but doesnt explain why you can or why you should set it this way over that way

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    Default Re: Jframe title setting question

    Quote Originally Posted by KevinWorkman View Post

    firePropertyChange("title", oldTitle, title);

    [/highlight]
    Kevin, I have a question for you. You used firePropertyChange what is the purpose for this and why. Sorry I have never figured out how to use this properly.

    thanks,

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    Default Re: Jframe title setting question

    Quote Originally Posted by derekxec View Post
    that does thank you very much...the book im reading says you can set either way but doesnt explain why you can or why you should set it this way over that way
    Use the constructor if you know the title at time you're creating a JFrame (which will be most cases, which is probably why it's provided. Use setTitle() if you have to set or change the title after the JFrame has already been created.
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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Jframe title setting question

    Quote Originally Posted by william View Post
    Kevin, I have a question for you. You used firePropertyChange what is the purpose for this and why. Sorry I have never figured out how to use this properly.

    thanks,
    Correction- I didn't use anything, that's just code I copied from the JDK source. Presumably, the firePropertyChange() method is called to generate a PropertyChangeEvent, which will be caught by any PropertyChangeListeners listening for the "title" property. For example:

    import java.awt.event.*;
    import java.beans.PropertyChangeEvent;
    import java.beans.PropertyChangeListener;
     
    import javax.swing.*;
     
     
    public class FrameListenersTest {
     
     
    	public FrameListenersTest(){
     
    		final JFrame frame = new JFrame("Listeners Test");
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setSize(200, 200);
     
    		frame.addPropertyChangeListener("title", new PropertyChangeListener(){
     
    			@Override
    			public void propertyChange(PropertyChangeEvent e) {
    				System.out.println("Old: " + e.getOldValue());
    				System.out.println("New: " + e.getNewValue());
    				System.out.println();
    			}
     
    		});
     
     
     
    		frame.setVisible(true);
     
     
    		Timer timer = new Timer(2000, new ActionListener(){
    			int i = 0;
    			public void actionPerformed(ActionEvent e){
    				i++;
    				frame.setTitle("Title " + i);
    			}
    		});
     
    		timer.start();
    	}
     
     
     
    	public static void main(String... args){
    		new FrameListenersTest();
    	}
    }

    PS- The person who wrote the code that uses the PropertyChangeListener in the Frame class seems to be Sami Shaio. I think he wrote a lot of the stuff in AWT. That's your bit of trivia for the day.
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  8. The Following User Says Thank You to KevinWorkman For This Useful Post:

    william (June 16th, 2011)

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