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Swing

Scheduled Pinned Locked Moved Java
helpjavasysadmindata-structures
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  • P pasztorpisti

    There you go. This time I compiled/tested it, contained another big mistake. Why have you used those stacks? You should check the error messages as well in the console output!!! You program threw exceptions!

    import java.awt.Button;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.util.Stack;

    import javax.swing.*;
    public class GUI extends JFrame implements ActionListener{
    JTextField input;
    JTextArea output;
    Button button;
    public GUI(){

    	setTitle("Satire v1.0.1");
	setSize(320,360);
	setLocationRelativeTo(null);
	setDefaultCloseOperation(EXIT\_ON\_CLOSE);
	
	JPanel panel = new JPanel();
	panel.setLayout(null);
	
	output = new JTextArea();
	output.setBounds(0, 0, 300, 300);
	output.setEditable(false);
	
	input = new JTextField();
	input.setBounds(0, 300, 260, 20);
	
	button = new Button("SEND");
	button.setBounds(250, 300, 50, 20);
	button.addActionListener(this);
	
	getContentPane().add(panel);
	panel.add(button);
	panel.add(input);
	panel.add(output);
}
public void actionPerformed(ActionEvent e) { 
	try{
		String out = input.getText();
		output.append(input.getText());
		input.selectAll();
		input.requestFocusInWindow();
	}catch(NullPointerException e3){}
}

public static void main(String\[\] args){
	 SwingUtilities.invokeLater(new Runnable() {
		 public void run(){
			 GUI cGUI = new GUI();
			 cGUI.setVisible(true);
		 }
	 });
}

    }

    J Offline
    J Offline
    Joshua Waring
    wrote on last edited by
    #6

    the purpose of the stack was for when I implements it into my chat client I'll have something to send it by, without changing the code around too much. I personally don't see how it caused an error.

    P 1 Reply Last reply
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    • J Joshua Waring

      the purpose of the stack was for when I implements it into my chat client I'll have something to send it by, without changing the code around too much. I personally don't see how it caused an error.

      P Offline
      P Offline
      pasztorpisti
      wrote on last edited by
      #7

      It caused an error because in java every object is used by reference. You had there a null reference to a stack object, actually you haven't created your stack object and when you tried to use it that was a NullPointerException! :-)

      J 1 Reply Last reply
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      • P pasztorpisti

        It caused an error because in java every object is used by reference. You had there a null reference to a stack object, actually you haven't created your stack object and when you tried to use it that was a NullPointerException! :-)

        J Offline
        J Offline
        Joshua Waring
        wrote on last edited by
        #8

        Meaning i should of put Stack incoming = new Stack();

        P J 2 Replies Last reply
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        • J Joshua Waring

          Meaning i should of put Stack incoming = new Stack();

          P Offline
          P Offline
          pasztorpisti
          wrote on last edited by
          #9

          Yep. Common mistake when starting java. In java only the primitive types are self contained, everything else is just a null or uninitialized reference without initialization.

          J 1 Reply Last reply
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          • J Joshua Waring

            Meaning i should of put Stack incoming = new Stack();

            J Offline
            J Offline
            Joshua Waring
            wrote on last edited by
            #10

            Any special features and tricks to Eclipse Debugger, I've hit an error while fusing it to the client. the server gets the connection but all input is just added to the JTextArea without being sent to the server even though it's told to send. I'd prefer to fix this one so I don't have to spam these forums.

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            • P pasztorpisti

              Yep. Common mistake when starting java. In java only the primitive types are self contained, everything else is just a null or uninitialized reference without initialization.

              J Offline
              J Offline
              Joshua Waring
              wrote on last edited by
              #11

              Hopefully you could help me with this one, I've found the problem (Thanks to the breakpoints) My main created a thread1 and then thread1 created thread 2, both of which contain a while(true) (Then just sit and wait for input and output) but when thread1 creates thread2 it doesn't go past the line which creates thread2 which Isn't what I thought would happen... I thought Thread1 would create thread2 then proceeds to the loop for user input.

              P 1 Reply Last reply
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              • J Joshua Waring

                Hopefully you could help me with this one, I've found the problem (Thanks to the breakpoints) My main created a thread1 and then thread1 created thread 2, both of which contain a while(true) (Then just sit and wait for input and output) but when thread1 creates thread2 it doesn't go past the line which creates thread2 which Isn't what I thought would happen... I thought Thread1 would create thread2 then proceeds to the loop for user input.

                P Offline
                P Offline
                pasztorpisti
                wrote on last edited by
                #12

                You are right that should happen.

                J 1 Reply Last reply
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                • P pasztorpisti

                  You are right that should happen.

                  J Offline
                  J Offline
                  Joshua Waring
                  wrote on last edited by
                  #13

                  I see no error but to call a implements Runnable I use the line,

                  (new Thread(new accept(br))).start();

                  if that helps

                  P 1 Reply Last reply
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                  • J Joshua Waring

                    I see no error but to call a implements Runnable I use the line,

                    (new Thread(new accept(br))).start();

                    if that helps

                    P Offline
                    P Offline
                    pasztorpisti
                    wrote on last edited by
                    #14

                    Not to be rude but maybe you should learn the basics first, correct threading is more or less an advanced topic. Actually the java tutorials put together by sun is exceptionally good: http://docs.oracle.com/javase/tutorial/[^] There is a paragraph on that page with "Trails Covering the Basics" header, you should read through that carefully, you will find topics about threading in the "Essential Java Classes" part, but read it from the beginning to the end without skipping. After this basic tutorial you won't ask questions like this.

                    1 Reply Last reply
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                    • J Joshua Waring

                      First lets give some context, I've just created a client and server but they don't work without using console So I've decided to create a GUI on top they'll communicate though the Stack, but that's all for a later date, right now I get a error on the Even listener which says that the JTextField is empty upon .getText() even though it's not. I've looked though it, but since I'm quite new to the whole Swing field, it's a challenge for me to fix the problem. It really is a simple GUI.

                      import java.awt.Button;
                      import java.awt.event.ActionEvent;
                      import java.awt.event.ActionListener;
                      import java.util.Stack;

                      import javax.swing.*;
                      public class GUI extends JFrame implements ActionListener{
                      Stack incoming = null;
                      Stack outgoing = null;
                      JTextField input;
                      JTextArea output;
                      Button button;
                      public GUI(){

                      	setTitle("Satire v1.0.1");
	setSize(320,360);
	setLocationRelativeTo(null);
	setDefaultCloseOperation(EXIT\_ON\_CLOSE);
	
	JPanel panel = new JPanel();
	panel.setLayout(null);
	
	output = new JTextArea();
	output.setBounds(0, 0, 300, 300);
	output.setEditable(false);
	
	input = new JTextField();
	input.setBounds(0, 300, 260, 20);
	
	button = new Button("SEND");
	button.setBounds(250, 300, 50, 20);
	button.addActionListener(this);
	
	getContentPane().add(panel);
	panel.add(button);
	panel.add(input);
	panel.add(output);
}
public void actionPerformed(ActionEvent e) { 
	GUI gui = new GUI();
	try{
		String out = gui.input.getText();
		gui.input.selectAll();
		outgoing.add(out);
	}catch(NullPointerException e3){}
	gui.output.append(outgoing.pop());
}

public static void main(String\[\] args){
	 SwingUtilities.invokeLater(new Runnable() {
		 public void run(){
			 GUI cGUI = new GUI();
			 cGUI.setVisible(true);
		 }
	 });
}

                      }

                      G Offline
                      G Offline
                      Gowtham Gutha
                      wrote on last edited by
                      #15

                      First of all you didn't set text in the JTextField and also you've not even enabled the user to write into the JTextField. Because, setEditable(false); means the user cannot edit the text in the text field and also there was no text in the Textfield. And also you do not need to create object for the class GUI in actionPerformed() because this method was written in the same class only. This means that you are performing action on the object 'g' which you've created. You can directly access them, there is no need of creating the object.

                      Gowtham Gutha (Java-Demos.Blogspot.Com)

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