Thread: More GUI help

Hello again,

I am making another test for my GUI and this one is supposed to have a couple of buttons that react and repaint the string that is displayed. Here is the code so far:

package Tests;
 
import java.awt.*;
import java.awt.Event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.*;
 
public class NumbersTest {
 
	private static class Display extends JPanel  {
 
		public String currentMessage = "Click a button and see what happens!";
 
		public void paintComponent(Graphics g)  {
 
			super.paintComponent(g);
			g.drawString(currentMessage, 50, 215);
 
 
		}
 
        private static class buttonHandler1 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #!";
 
			}
 
		}
 
        private static class buttonHandler2 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #2!";
			}
 
		}
 
		private static class buttonHandler3 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #3!";
			}
 
		}
 
		private static class closeButtonHandler implements ActionListener {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e)  {
 
				System.exit(0);
 
			}
 
		}
 
		public static void main(String[] arg)  {
 
			String currentMessage;
 
			Display displayPanel = new Display();
			JButton button1 = new JButton("Button #1");
			JButton button2 = new JButton("Button #2");
			JButton button3 = new JButton("Button #3");
			JButton closeButton = new JButton("Close");
			buttonHandler1 listenerb1 = new buttonHandler1();
			buttonHandler2 listenerb2 = new buttonHandler2();
			buttonHandler3 listenerb3 = new buttonHandler3();
		    closeButtonHandler closelistener = new closeButtonHandler();
 
		    button1.addActionListener(listenerb1);
		    button2.addActionListener(listenerb2);
		    button3.addActionListener(listenerb3);
		    closeButton.addActionListener(closelistener);
 
		    JPanel content = new JPanel();
		    content.setLayout(new BorderLayout());
		    content.add(displayPanel, BorderLayout.CENTER);
		    content.add(button1, BorderLayout.NORTH);
		    content.add(button2, BorderLayout.WEST);
		    content.add(button3, BorderLayout.EAST);
		    content.add(closeButton, BorderLayout.SOUTH);
		    content.setVisible(true);
 
		    JFrame window = new JFrame("Numbers and Buttons");
			window.setContentPane(content);
	        window.setSize(500, 500);
			window.setLocation(100, 100);
			window.setVisible(true);
 
 
 
		}
 
	}
 
}

How do I make it so that when the buttons are clicked, it repaints the string displayed to whatever I want it to? I was thinking repaint(); but I'm not sure.

Help?

-Silent

Calling repaint() will cause the java program to call the paintComponent method very soon afterwards.
You will have to tell the paintComponent method what String you want it to draw.

OK, so how do I call repaint()?

objectReference.repaint();

So, in this case, what is my object reference that would work in this context?

Well, the paintComponent method is in the Display routine (or class).

what is my object reference that would work

paintComponent method is in the Display routine (or class).

You would need a reference to the instance of the Display class.

Your nested classes will be a problem. An inner class would be able to see the variables of the class that it is in.
The static nested classes will need a reference to any class whose variables it wants to access.

Uhh... I think I get what your saying. Would you mind quick throwing together some code so I can see what you really mean?

Alright, thanks. I will look at the tut.

Ok, so I read up on the nested classes thing and I edited the code, and the repaint() is not underlined, so that's a good sign. Here is the code:

package Tests;
 
import java.awt.*;
import java.awt.Event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.*;
 
public class NumbersTest {
 
	private class Display extends JPanel  {
 
		public String currentMessage = "Click a button and see what happens!";
 
		public void paintComponent(Graphics g)  {
 
			super.paintComponent(g);
			g.drawString(currentMessage, 50, 215);
 
 
		}
 
        private class buttonHandler1 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #!";
				repaint(currentMessage);
 
			}
 
		}
 
        private class buttonHandler2 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #2!";
				repaint(currentMessage);
			}
 
		}
 
		private class buttonHandler3 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #3!";
				repaint(currentMessage);
			}
 
		}
 
		private class closeButtonHandler implements ActionListener {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e)  {
 
				System.exit(0);
 
			}
 
		public static void main(String[] arg)  {
 
			String currentMessage;
 
			Display displayPanel = new Display();
			JButton button1 = new JButton("Button #1");
			JButton button2 = new JButton("Button #2");
			JButton button3 = new JButton("Button #3");
			JButton closeButton = new JButton("Close");
			buttonHandler1 listenerb1 = new buttonHandler1();
			buttonHandler2 listenerb2 = new buttonHandler2();
			buttonHandler3 listenerb3 = new buttonHandler3();
		    closeButtonHandler closelistener = new closeButtonHandler();
 
		    button1.addActionListener(listenerb1);
		    button2.addActionListener(listenerb2);
		    button3.addActionListener(listenerb3);
		    closeButton.addActionListener(closelistener);
 
		    JPanel content = new JPanel();
		    content.setLayout(new BorderLayout());
		    content.add(displayPanel, BorderLayout.CENTER);
		    content.add(button1, BorderLayout.NORTH);
		    content.add(button2, BorderLayout.WEST);
		    content.add(button3, BorderLayout.EAST);
		    content.add(closeButton, BorderLayout.SOUTH);
		    content.setVisible(true);
 
		    JFrame window = new JFrame("Numbers and Buttons");
			window.setContentPane(content);
	        window.setSize(500, 500);
			window.setLocation(100, 100);
			window.setVisible(true);
 
 
 
		}
 
	}
 
		public void repaint(String currentMessage2) {
 
 
		}
 
	}
 
}

But, the public static void main(String[] arg) apparently has an error, and it says:

The method main cannot be declared static; static methods can only be declared in a static or top level type

Help?

static methods can only be declared in a static or top level type

That says what the problem is. A static method can only be in a static or top level class.
Move the main method or make the class it is in static.

Why do you have the NumbersTest class?

Why do you have so many variables with the same name: currentMessage?

Oh, woops. I can delete those.

The first question, not sure what to say.

And, I'm supposed to move the main() method to.... where?

Out of an inner, non static class.

Why do you have the NumbersTest class?

Because I want to test my abilities with GUI?

Alright, I am very annoyed at myself. I make SOOOO many typos.

It was just a typo. Thanks

Ok, so now, when I fix the typo, something in the main() routine apparently has an error:

package Tests;
 
import java.awt.*;
import java.awt.Event.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.*;
 
public class NumbersTest {
 
	private class Display extends JPanel  {
 
		public String currentMessage = "Click a button and see what happens!";
 
		public void paintComponent(Graphics g)  {
 
			super.paintComponent(g);
			g.drawString(currentMessage, 50, 215);
 
 
		}
 
	}
 
        private class buttonHandler1 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #!";
				repaint(currentMessage);
 
			}
 
		}
 
        private class buttonHandler2 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #2!";
				repaint(currentMessage);
			}
 
		}
 
		private class buttonHandler3 implements ActionListener  {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e) {
				currentMessage = "You clicked Button #3!";
				repaint(currentMessage);
			}
 
		}
 
		private class closeButtonHandler implements ActionListener {
 
			String currentMessage;
 
			public void actionPerformed(ActionEvent e)  {
 
				System.exit(0);
 
			}
 
		}
 
	    public static void main(String[] args)  {
 
			String currentMessage;
 
			Display displayPanel = new Display();
			JButton button1 = new JButton("Button #1");
			JButton button2 = new JButton("Button #2");
			JButton button3 = new JButton("Button #3");
			JButton closeButton = new JButton("Close");
			buttonHandler1 listenerb1 = new buttonHandler1();
			buttonHandler2 listenerb2 = new buttonHandler2();
			buttonHandler3 listenerb3 = new buttonHandler3();
		    closeButtonHandler closelistener = new closeButtonHandler();
 
		    button1.addActionListener(listenerb1);
		    button2.addActionListener(listenerb2);
		    button3.addActionListener(listenerb3);
		    closeButton.addActionListener(closelistener);
 
		    JPanel content = new JPanel();
		    content.setLayout(new BorderLayout());
		    content.add(displayPanel, BorderLayout.CENTER);
		    content.add(button1, BorderLayout.NORTH);
		    content.add(button2, BorderLayout.WEST);
		    content.add(button3, BorderLayout.EAST);
		    content.add(closeButton, BorderLayout.SOUTH);
		    content.setVisible(true);
 
		    JFrame window = new JFrame("Numbers and Buttons");
			window.setContentPane(content);
	        window.setSize(500, 500);
			window.setLocation(100, 100);
			window.setVisible(true);
 
 
 
		}
 
 
		public void repaint(String currentMessage2) {
 
 
		}
 
	}

The new Display(); in Display displayPanel = new Display(); is underlined and it says

No enclosing instance of type NumbersTest is accessible. Must qualify the allocation with an enclosing instance of type NumbersTest (e.g. x.new A() where x is an instance of NumbersTest).

Honestly, I have absolutely no idea what this means.

Anybody else know?

I think the link I posted in #10 discusses this. The Display class is an inner class. You need an instance of the NumbersTest class to be able to create a Display class object.

Why not get rid of the NumbersTest class? Or move the Display class out of the NumbersTestClass?
Or move all of the code in the main() method into the NumbersTest class's constructor and have the main() method just create an instance of NumbersTest?

Wait... What? Ok, I am so very confused. I'm just going to let this project drop.

Get rid of the NumbersTest class and use the Display class.