JPanel In Standalone Class

[Laidler]

I now have teo classes the first one contains this

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

class fm1 extends JPanel
{
	public fm1()
	{
		this.setLayout(new GridLayout(3,0));
		Dimension D1 = new Dimension (300, 300);

		JLabel fruit1 = new JLabel();
		fruit1.setPreferredSize(D1);		
		fruit1.setOpaque(true);
		this.add(fruit1);

		JLabel fruit2 = new JLabel();
 		fruit2.setPreferredSize(D1);		
		fruit2.setOpaque(true);
		this.add(fruit2);

		JLabel fruit3 = new JLabel();
		fruit3.setPreferredSize(D1);		
		fruit3.setOpaque(true);
		this.add(fruit1);
	}
}

This is the Standalone Class and it compiles fine

I then have this one

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

class FruitWnd
{
    public static void main(String[] args) 
    {
	// Create and set up the JFrame
        JFrame myWindow = new JFrame("Fruit Machine");
        
        // Set the default close operation of the JFrame object to dispose
       	myWindow.setDefaultCloseOperation(3);
        
  		// Instance the standalone class containing the components
  		fm1 FruitMachine = new fm1();
      	
      	// Add intermediate container to top level container
        myWindow.add(FruitMachine,BorderLayout.CENTER);
        
		// Display the window.
        myWindow.pack();
        myWindow.setVisible(true);
	    
    }// end of main method
    
}// end of class

When i Try to compile it it says that it cant find the fm1 class symbol. however on a very similar code it will compile it and i cant see the difference in order for me to solve it. can anyone help?

[javaAddict]

Are both classes in the same folder?

[Laidler]

Are both classes in the same folder?

the two java files are in same folder, the second class hasnt been compiled so there isnt two .class files

[Ezzaral]

Are your class files in a different folder than your source files? Do the file names match the class names?

[Laidler]

yes and yes (im assuming by source files you mean the .java files) the two files are fm1.java and FruitWnd.java

[Laidler]

If it helps heres the programs i based them on

fm1.java is based on TilePanelA.java which is

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

class TilePanelA extends JPanel implements MouseListener
{
	public TilePanelA() 
	{
		this.setLayout(new GridLayout(3,0));
		Dimension D1 = new Dimension (230, 443);
				
		JLabel L1 = new JLabel();
		L1.setPreferredSize(D1);		
		L1.setBackground(Color.WHITE);
		L1.setOpaque(true);
		this.add(L1);
				
		JLabel L2 = new JLabel();  
		L2.setPreferredSize(D1);
		L2.setBackground(Color.WHITE);
		L2.setOpaque(true);
		this.add(L2);
				
		JLabel L3 = new JLabel(); 
		L3.setPreferredSize(D1); 
		L3.setBackground(Color.WHITE);
		L3.setOpaque(true);
		this.add(L3);
		
		JLabel L4 = new JLabel();  
		L4.setPreferredSize(D1);
		L4.setBackground(Color.WHITE);
		L4.setOpaque(true);
		this.add(L4);
		
		JLabel L5 = new JLabel();  
		L5.setPreferredSize(D1);
		L5.setBackground(Color.WHITE);
		L5.setOpaque(true);
		this.add(L5);
		
		JLabel L6 = new JLabel();  
		L6.setPreferredSize(D1);
		L6.setBackground(Color.WHITE);
		L6.setOpaque(true);
		this.add(L6);
		
		JLabel L7 = new JLabel();  
		L7.setPreferredSize(D1);
		L7.setBackground(Color.WHITE);
		L7.setOpaque(true);
		this.add(L7);
		
		JLabel L8 = new JLabel();  
		L8.setPreferredSize(D1);
		L8.setBackground(Color.WHITE);
		L8.setOpaque(true);
		this.add(L8);
		
		JLabel L9 = new JLabel();
		L9.setPreferredSize(D1);
		L9.setBackground(Color.WHITE);
		L9.setOpaque(true);
		this.add(L9);
	} // end of constructor

	public void mouseEntered (MouseEvent me)
	{
	}
	public void mouseExited (MouseEvent me)
	{
	}
	public void mousePressed (MouseEvent me)
	{
	}
	public void mouseReleased (MouseEvent me)
	{
	}
	public void mouseClicked (MouseEvent me)
	{
		Color labelColor = me.getComponent().getBackground();
		if( labelColor == Color.WHITE)
		{
			me.getComponent().setBackground(Color.BLACK);	
		}
		else
		{
			me.getComponent().setBackground(Color.WHITE);
		}
	}
} // end of class

the Main difference between the two is the bits about the action listener and the number of panels

FruitWnd.java is based on tileExercise.java which is:

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

class TileExercise
{
    public static void main(String[] args) 
    {
	// Create and set up the JFrame
        JFrame myWindow = new JFrame("Tile Exercise");
        
        // Set the default close operation of the JFrame object to dispose
       	myWindow.setDefaultCloseOperation(3);
        
  		// Instance the standalone class containing the components
  		TilePanelA tpa = new TilePanelA();
      	
      	// Add intermediate container to top level container
        myWindow.add(tpa,BorderLayout.CENTER);
        
		// Display the window.
        myWindow.pack();
        myWindow.setVisible(true);
	    
    }// end of main method
    
}// end of class

TilePanelA and tileExercise both compile correctly

[javaAddict]

Well I run them at my computer and there is no syntax error. Your class cannot find the fm1

[Laidler]

well i knew that i want to know why it cant and how to make it so it can be found

[Ezzaral]

Well, not knowing your exact directory structures and where your output class files are located (you said they were in different directories), I would recommend compiling all of those java files at the same time with javac *.java . It's just a simple classpath problem that you are encountering. There is nothing wrong with the code itself.

[Laidler]

Thnx for that command it compiled the FruitWnd class, however when i tried to run the code it didnt work i got this error in the cmd output

C:\Users\Chris\Documents\Java\ICA2\Source and classes>java FruitWnd
Exception in thread "main" java.lang.NoClassDefFoundError: FruitWnd
Caused by: java.lang.ClassNotFoundException: FruitWnd
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
Could not find the main class: FruitWnd. Program will exit.

whats causing the error

note that FruitWnd.java is almost identical to TileExercise.java which does compile and run

[Ezzaral]

This article/tutorial on the class path may help in understanding the issue further, if you want to know the "why" of it: http://www.kevinboone.com/classpath.html

[Ezzaral]

Are you running it from the directory that contains that class file?

[Laidler]

the .java files and the .class files are both in the same directory which is C:\Users\Chris\Documents\Java\ICA2\Source and classes>

[Laidler]

unless you mean the fm1 class being in the fm1.java file instead of the Fruitwnd.java file