program not running

[levi sleight]

so i made a program that just puts a couple of shapes on the screen which i this:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class grape2 extends JFrame{
	
	public void paintComponent(Graphics g){
		super.paintComponents(g);
		this.setBackground(Color.WHITE);
		
		g.setColor(Color.BLUE);
		g.drawLine( 10, 25, 200, 45);
		
		g.setColor(Color.RED);
		g.drawRect(10, 55, 100, 30);
		
		g.setColor(Color.GREEN);
		g.fillOval(10, 95, 100, 30);
		
		g.setColor(Color.ORANGE);
		g.fill3DRect(10, 160, 100, 50, true);
	}	
}

so after that i made a new classs to run it which is here:

import java.awt.Color;
import javax.swing.*;

public class grape2run {
	public static void main(String[] args) {
		JFrame f = new JFrame("title");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		grape2 t = new grape2();
		f.add(t);
		f.setSize(500,450);
		f.setVisible(true);
		t.setBackground(Color.WHITE);

	}

}

but it gave me ab error when i tried to run it which is this:

Exception in thread "main" java.lang.IllegalArgumentException: adding a window to a container
at java.awt.Container.checkNotAWindow(Unknown Source)
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at javax.swing.JFrame.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at grape2run.main(grape2run.java:9)


i really have no idea what to do. oh also im using eclipse, one of the newest versions

[Jelle Klap]

You're adding a JFrame, an instance of grape2, to another JFrame, referenced by variable f in grape2run.
That's not allowed. Try making grape2 a subclass of JPanel instead.

Also I'm moving this to our Swing / AWT / SWT forum for you

[levi sleight]

blah, i knew it was something dumb like that, thanks. its fixed

[K. Tsang]

Further to Jelle's reply, another way of doing this is directly creating the JFrame as your main window like this:

import java.awt.Color;
import javax.swing.*;

public class grape2run {
	public static void main(String[] args) {
		grape2 t = new grape2(); // grape2() is a JFrame itself
		t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		t.setBackground(Color.WHITE); // not really needed because you already done this is grape2
		t.setSize(500,450); // you can also use pack() to only display the components you added to the JFrame
		t.setVisible(true);

	}

}

[Darryl Burke]

K. Tsang wrote:Further to Jelle's reply, another way of doing this is directly creating the JFrame as your main window like this:

But respect Swing's single threaded rule. All Swing component constructors and methods should be invoked on the EDT, barring the very few that are still documented as being thread safe in the JDK7 documentation.