"No main classes found" - can't compile anything in Java Netbeans 7.1

[Download]

I just started Java as part of my Engineering Degree at uni. One of my first (and rather simple) projects is to create this picture using java.awt. Whenever I compile it it get the message: "No main classes found"

Can anyone help me here? I would normally go in a ask a lecturer but it's a public holiday so everyone is at home

[Doritos_Man]

Can you provide us the code your using?

[Download]

//<editor-fold defaultstate="collapsed" desc="Package Header">
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package lab1_4;
//</editor-fold>

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

//<editor-fold defaultstate="collapsed" desc="Class Declaration">
/**
 *
 * @author COMP1102
 */
public class Lab1_4 extends JApplet {

    /**
     * Initialization method that will be called after the applet is loaded into
     * the browser.
     */
    public void init() {
        // TODO start asynchronous download of heavy resources
        setSize(400,300);
    }
    

    // TODO overwrite start(), stop() and destroy() methods
    //</editor-fold>
    
    
    public void paint(Graphics page) {
        //Add your code here
        
        page.setColor (Color.red); //Red, top left corner
        page.fillRect (0, 0, 200, 150);
        
        page.setColor (Color.blue); //Blue, top right corner
        page.fillRect (200, 0, 200, 150);
        
        page.setColor (Color.yellow); //Yellow, bottom left corner
        page.fillRect (0, 150, 200, 150);
        
        page.setColor (Color.green); //Green, bottom right corner
        page.fillRect (200, 150, 200, 150);
        
        page.drawLine (0, 150, 200, 0); //Diagonal lines
        page.drawLine (200, 0, 400, 150);
        page.drawLine (0, 150, 200, 300);
        page.drawLine (200, 300, 400, 150);
        
        page.setColor (Color.yellow); //Yellow part of centre circle
        page.fillArc (200, 150, 100, 100, 0, 90);
        
        page.drawArc (200, 150, 100, 100, 90, 180); //Uncoloured part of centre circle (red sector)
        
        page.setColor (Color.blue); //Blue part of centre circle
        page.fillArc (200, 150, 100, 100, 180, 270);
        
        page.drawArc (200, 150, 100, 100, 270, 360); //Uncoloured part of circle (green sector)
        
        
    }
}

We're supposed to be recreating this:

[img]http://i.imgur.com/sHu7L.png[/img]

[Doritos_Man]

public static void main(String [ ] args)
{
      //Code Here
}

Your missing this.

Read up on the main method here:
[url]http://docs.oracle.com/javase/tutorial/getStarted/application/index.html[/url]

[Download]

[QUOTE=Doritos_Man;35102289]

public static void main(String [ ] args)
{
      //Code Here
}

Your missing this.

Read up on the main method here:
[url]http://docs.oracle.com/javase/tutorial/getStarted/application/index.html[/url][/QUOTE]

I thought this:

public void paint(Graphics page) {
        //Add your code here
}

Did that

[Doritos_Man]

[QUOTE=download;35102311]I thought this:

public void paint(Graphics page) {
        //Add your code here
}

Did that[/QUOTE]

Every application in Java needs a main method.
It runs everything in Main, without it Java doesn't know where to start.

[editline]11th March 2012[/editline]

//<editor-fold defaultstate="collapsed" desc="Package Header">
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package lab1_4;
//</editor-fold>

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

//<editor-fold defaultstate="collapsed" desc="Class Declaration">
/**
 *
 * @author COMP1102
 */
public class Lab1_4 extends JApplet {

    public static void main(String [ ] args){  
    }
    /**
     * Initialization method that will be called after the applet is loaded into
     * the browser.
     */
    public void init() {
        // TODO start asynchronous download of heavy resources
        setSize(400,300);
    }
    

    // TODO overwrite start(), stop() and destroy() methods
    //</editor-fold>
    
    
    public void paint(Graphics page) {
        //Add your code here
        
        page.setColor (Color.red); //Red, top left corner
        page.fillRect (0, 0, 200, 150);
        
        page.setColor (Color.blue); //Blue, top right corner
        page.fillRect (200, 0, 200, 150);
        
        page.setColor (Color.yellow); //Yellow, bottom left corner
        page.fillRect (0, 150, 200, 150);
        
        page.setColor (Color.green); //Green, bottom right corner
        page.fillRect (200, 150, 200, 150);
        
        page.drawLine (0, 150, 200, 0); //Diagonal lines
        page.drawLine (200, 0, 400, 150);
        page.drawLine (0, 150, 200, 300);
        page.drawLine (200, 300, 400, 150);
        
        page.setColor (Color.yellow); //Yellow part of centre circle
        page.fillArc (200, 150, 100, 100, 0, 90);
        
        page.drawArc (200, 150, 100, 100, 90, 180); //Uncoloured part of centre circle (red sector)
        
        page.setColor (Color.blue); //Blue part of centre circle
        page.fillArc (200, 150, 100, 100, 180, 270);
        
        page.drawArc (200, 150, 100, 100, 270, 360); //Uncoloured part of circle (green sector)
        
        
    }
}

Fixed it but your thing doesn't show up like it's supposed to but it's close.

[Download]

//******************************************************************** 
// Snowman.java Author: Lewis/Loftus 
// 
// Demonstrates basic drawing methods and the use of color. 
//******************************************************************** 

import javax.swing.JApplet;
import java.awt.*; 
public class Snowman extends JApplet { 

//----------------------------------------------------------------- 
// Draws a snowman. 
//----------------------------------------------------------------- 

public void paint (Graphics page) 
{ final int MID = 150; 
final int TOP = 50; 
setBackground (Color.cyan); 
page.setColor (Color.blue); 
page.fillRect (0, 175, 300, 50); 

// ground 

page.setColor (Color.yellow); 
page.fillOval (-40, -40, 80, 80); 

// sun

page.setColor (Color.white); 
page.fillOval (MID-20, TOP, 40, 40); 

// head 

page.fillOval (MID-35, TOP+35, 70, 50); 

// upper torso 

page.fillOval (MID-50, TOP+80, 100, 60); 

// lower torso 

page.setColor (Color.black); 
page.fillOval (MID-10, TOP+10, 5, 5); 

// left eye 

page.fillOval (MID+5, TOP+10, 5, 5); 

// right eye 

page.drawArc (MID-10, TOP+20, 20, 10, 190, 160); 

// smile 

page.drawLine (MID-25, TOP+60, MID-50, TOP+40); 

// left arm 

page.drawLine (MID+25, TOP+60, MID+55, TOP+60); 

// right arm 

page.drawLine (MID-20, TOP+5, MID+20, TOP+5); 

// brim of hat 

page.fillRect (MID-15, TOP-20, 30, 25); 

// top of hat 

} } 

What about this? It's the demo code that my lecturer used, lacks a main method but it works?

[Doritos_Man]

[QUOTE=download;35102510]

//******************************************************************** 
// Snowman.java Author: Lewis/Loftus 
// 
// Demonstrates basic drawing methods and the use of color. 
//******************************************************************** 

import javax.swing.JApplet;
import java.awt.*; 
public class Snowman extends JApplet { 

//----------------------------------------------------------------- 
// Draws a snowman. 
//----------------------------------------------------------------- 

public void paint (Graphics page) 
{ final int MID = 150; 
final int TOP = 50; 
setBackground (Color.cyan); 
page.setColor (Color.blue); 
page.fillRect (0, 175, 300, 50); 

// ground 

page.setColor (Color.yellow); 
page.fillOval (-40, -40, 80, 80); 

// sun

page.setColor (Color.white); 
page.fillOval (MID-20, TOP, 40, 40); 

// head 

page.fillOval (MID-35, TOP+35, 70, 50); 

// upper torso 

page.fillOval (MID-50, TOP+80, 100, 60); 

// lower torso 

page.setColor (Color.black); 
page.fillOval (MID-10, TOP+10, 5, 5); 

// left eye 

page.fillOval (MID+5, TOP+10, 5, 5); 

// right eye 

page.drawArc (MID-10, TOP+20, 20, 10, 190, 160); 

// smile 

page.drawLine (MID-25, TOP+60, MID-50, TOP+40); 

// left arm 

page.drawLine (MID+25, TOP+60, MID+55, TOP+60); 

// right arm 

page.drawLine (MID-20, TOP+5, MID+20, TOP+5); 

// brim of hat 

page.fillRect (MID-15, TOP-20, 30, 25); 

// top of hat 

} } 

What about this? It's the demo code that my lecturer used, lacks a main method but it works?[/QUOTE]

Hmm that is weird.
Your code and that code both work in Eclipse fine.

[Download]

[QUOTE=Doritos_Man;35102590]Hmm that is weird.
Your code and that code both work in Eclipse fine.[/QUOTE]

Maybe because it's an applet? Just a guess.

Neither of those codes (my original, mine modified, and the demo code) work in netbeans. I'm thinking something bigger is off. I'm still getting the "No main classes found" error

[Elv02]

When you create your new class file, are you creating just a regular default class? You need to make sure you select Java Main Class from the file menu. That should fix it.

[Download]

Fixed it.

[Zyx]

Since you're using an Applet you don't need a main method.
Just right click on the Applet form and click run.

You can also launch it with an html file:

<html>
  <body>
    <applet code="lab1_4.Lab1_4.class"
            archive="relative OR full path to compiled .jar"
            width="400" height="300" >
    </applet>
  </body>
</html>