graphics won't change

I am using these if statements to change which line is drawn, but the line never changes and I dont' know why. Heres my code:

Code:

---

import java.applet.*;
import java.awt.*;

public class DrawingLines extends Applet {

  int width, height, x;
  Boolean wait = true;

  public void init() {
      x = 1;
      width = getSize().width;
      height = getSize().height;
      setBackground( Color.black );

  }

  public void main(String args[]) {
      try
      {
      Thread.sleep(2000); // do nothing for 1000 miliseconds (1 second)
      }
      catch(InterruptedException e)
      {
      e.printStackTrace();
      }
      wait = false;
  }

  public void paint( Graphics g ) {
      repaint();
      g.setColor( Color.green );
      if (wait == true) {
              g.drawLine(20, 20, 100, 100);
      }
      if (wait == false) {
              g.drawLine(0, 0, 150, 100);
      }
  }
}

---

Hope someone can fix it, thanks in advance.

I don't usually do graphics work but I'm pretty sure you need to call repaint() after you draw anything new for it to show up.

Try debugging your code by adding a println() in the methods to see if they are being called.

A main( ... ) method in an Applet? Go read some tutorials first and don't guess ...

kind regards,

Jos

hey
i want to calculate area of given land
coordinates may entered at execution time.
plz help me
with applet

Quote:

---

Originally Posted by devang_tandel

i want to calculate area of given land
coordinates may entered at execution time.
plz help me
with applet

---

Don't hijack someone else's thread; start your own.

Jos

Well I looked for tutorials, but I couldn't find anything for making new graphics, I found stuff about repaint() and double buffering but not changing a line to a box for example.

Quote:

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Originally Posted by pizzadude223

Well I looked for tutorials, but I couldn't find anything for making new graphics, I found stuff about repaint() and double buffering but not changing a line to a box for example.

---

That is still no excuse for having a main( ... ) method in an Applet because it will never be called. There's an init() method and a start() method for that; like I wrote: read some (relevant) tutorials.

kind regards,

Jos

Quote:

---

Try debugging your code by adding a println() in the methods to see if they are being called.

---

Have you tried that to see what methods in your code are being called? Or NOT called.

I'm compiling with notepad and don't really have anything else that will actually say stuff with println(), so what program would I use with that?

I got it by changing the main method to the start() method, thanks.

Sorry, what I meant by println() is System.out.println()

Quote:

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Originally Posted by Norm

Have you tried that to see what methods in your code are being called? Or NOT called.

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That one is easy; on page one of any Applet tutorial it says that a (J)Applet doesn't have a main( ... ) method; it has an init() method and a start() method and a couple more. The OP should do some reading instead of making wild guesses and wishful thinking.

kind regards,

Jos

Strictly speaking an applet can have a main() method. It just won't be called by the JVM when the applet is started executing by the JVM in a browser. It would be called if the applet was started by the command: java DrawLines

The problem was the OP expected it to be called. A println() would show it wasn't.
Assumptions can lead you astray. Adding println()s will show you what is happening.

Quote:

---

Originally Posted by prabhudass

sir u see the the java progam code it is sample for java and it is write code
and it is big program.

---

Please stop posting information-less nonsense all over the place.

kind regards,

Jos

You are looking for a way to begin the execution
of your experimental algorithm.

There are two ways to do this in java.

For Applets, you write a start(){...} method.
For Applications you write a main(String args[]){...}
method (sometimes referred to as the "launch point").

Since you are working with an applet, you
need to add a start(){...} method to get
your applet running.

You don't have to get rid of the main(String args[]){...}
method in your code, but it looks obviously amature.

I have added the following start(){...} method to
your applet:

Code:

---

  public void start() {
    main( new String[]{"dummy string"} );
  }

---

Notice the weird call to your main(String[] args){...}
method.

This code runs.

Code:

---

import java.applet.*;
import java.awt.*;

public class DrawingLines extends Applet {

  int width, height, x;
  Boolean wait = true;

  public void init() {
      x = 1;
      width = getSize().width;
      height = getSize().height;
      setBackground( Color.black );
  }

  public void start() {
    main( new String[]{"dummy string"} );  // Silly, but neccessary to
  }                                        // call your main method.

  public void main(String args[]) {
      try {
        Thread.sleep(2000); // do nothing for 1000 miliseconds (1 second)
      }
      catch(InterruptedException e){
        e.printStackTrace();
      }
      wait = false;
  }

  public void paint( Graphics g ) {
      repaint();
      g.setColor( Color.green );
      if (wait == true) {
              g.drawLine(20, 20, 100, 100);
      }
      if (wait == false) {
              g.drawLine(0, 0, 150, 100);
      }
  }
}

---

Here is your applet without the main(String[] args){...}
method. I haven't tested it. It should produce the same
results as the code above.

Code:

---

import java.applet.*;
import java.awt.*;

public class DrawingLines extends Applet {

  int width, height, x;
  Boolean wait = true;

  public void init() {
      x = 1;
      width = getSize().width;
      height = getSize().height;
      setBackground( Color.black );
  }

  public void start() {
      try {
        Thread.sleep(2000); // do nothing for 1000 miliseconds (1 second)
      }
      catch(InterruptedException e){
        e.printStackTrace();
      }
      wait = false;
  }

  public void paint( Graphics g ) {
      repaint();
      g.setColor( Color.green );
      if (wait == true) {
              g.drawLine(20, 20, 100, 100);
      }
      if (wait == false) {
              g.drawLine(0, 0, 150, 100);
      }
  }
}

---