



NULL Layout


Sometimes getting components onto your applet or application in the exact
location you desire is a maddening process. One way of dealing with the
situation is to set the layout to NULL:
      setLayout(null);



Using null Layout: The following code illustrates how
to use null layout. The first thing you have to do is set the Layout
to null. The second thing you have to do is manually set the location
of the item. Finally you have to set the size of the item. If you have
a lot of components, you have to do a lot of repetitious work.

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

public class lay extends Applet{

 public void init() {
      setBackground(Color.magenta);
      setLayout(null);
      Button b = new Button("PRESS");
      b.setBackground(Color.yellow);
      TextField tf = new TextField();
      Choice ch = new Choice();
      ch.setBackground(Color.white);
      ch.addItem("Mushrooms");
      ch.addItem("Artichokes");
      ch.addItem("Peppers");
      ch.addItem("Onions");
      ch.setLocation(10,10); ch.setSize(90,20);
      b.setLocation(120,10); b.setSize(50,20);
      tf.setLocation(190,10); tf.setSize(60,20);
      add(b); add(tf); add(ch);
    }
}
//<applet code=lay.class height=120 width=270></applet>






Dealing With Lots of Components: Sometimes you have a lot
of components to place on a page, but they are arranged in orderly rows or
some other pattern. Here's a little example:


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

public class many extends Applet{

  Button[] b = new Button[30];

  public void init(){
    setBackground(Color.red);
    setLayout(null);
    int i=0;
    for(int x=10; x<320; x+=70)
      for(int y=10; y<180; y+=30) {
        b[i] = new Button("Press" + (i+1));
        b[i].setLocation(x,y);
        b[i].setSize(60,20);
        b[i].setBackground(Color.black);
        b[i].setForeground(Color.cyan);
        add(b[i]);
        i++;
      }
  }
}
//<applet code=many.class height=200 width=360></applet>











Choice: 

Study the first example on this page and make sure that you can use the Choice
component. You may need this one in the future. Also notice the embedded for-loop in
the second example. Familiarize yourself with it, but you may or may not understand it
at this point. But, FYI, the outer loop counts from 10 to 320 by 70. The inner loop
counts from 10 to 180 by 30. So, the outer loop iterates five times since the increment is
performed AFTER the iteration. The inner loop iterates six times. This gives us a total
of 5x6=30 iterations for the code contained inside the loop. Each time setLocation is called
either x and/or y has a different value.