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Exploring Java

Previous Chapter 12
Layout Managers

12.2 GridLayout

GridLayout arranges components into regularly spaced rows and columns. The components are arbitrarily resized to fit in the resulting areas; their minimum and preferred sizes are consequently ignored. GridLayout is most useful for arranging very regular, identically sized objects and for allocating space for Panels to hold other layouts in each region of the container.

GridLayout takes the number of rows and columns in its constructor. If you subsequently give it too many objects to manage, it adds extra columns to make the objects fit. You can also set the number of rows or columns to zero, which means that you don't care how many elements the layout manager packs in that dimension. For example, GridLayout(2,0) requests a layout with two rows and an unlimited number of columns; if you put ten components into this layout, you'll get two rows of five columns each.

The following applet sets a GridLayout with three rows and two columns as its layout manager; the results are shown in Figure 12.3.

import java.awt.*; 
public class Grid extends java.applet.Applet {  
    public void init() { 
        setLayout( new GridLayout( 3, 2 )); 
        add( new Button("One") ); 
        add( new Button("Two") ); 
        add( new Button("Three") ); 
        add( new Button("Four") ); 
        add( new Button("Five") ); 

The five buttons are laid out, in order, from left to right, top to bottom, with one empty spot.

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