AWT GridBagLayout Class

Introduction

The class GridBagLayout arranges components in a horizontal and vertical manner.

Class declaration

Following is the declaration for java.awt.GridBagLayout class:

public class GridBagLayout
   extends Object
      implements LayoutManager2, Serializable

Field

Following are the fields for java.awt.BorderLayout class:

• double[] columnWeights -- This field holds the overrides to the column weights.

• int[] columnWidths -- This field holds the overrides to the column minimum width.

• protected Hashtable comptable -- This hashtable maintains the association between a component and its gridbag constraints.

• protected GridBagConstraints defaultConstraints -- This field holds a gridbag constraints instance containing the default values, so if a component does not have gridbag constraints associated with it, then the component will be assigned a copy of the defaultConstraints.

• protected java.awt.GridBagLayoutInfo layoutInfo -- This field holds the layout information for the gridbag.

• protected static int MAXGRIDSIZE -- The maximum number of grid positions (both horizontally and vertically) that can be laid out by the grid bag layout.

• protected static int MINSIZE -- The smallest grid that can be laid out by the grid bag layout.

• protected static int PREFERREDSIZE -- The preferred grid size that can be laid out by the grid bag layout.

• int[] rowHeights -- This field holds the overrides to the row minimum heights.

• double[] rowWeights -- This field holds the overrides to the row weights.

Class constructors

Class methods

Methods inherited

This class inherits methods from the following classes:

• java.lang.Object

GridBagLayout Example

Create the following java program using any editor of your choice in say D:/ > AWT > com > tutorialspoint > gui >

package com.tutorialspoint.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtLayoutDemo {
   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;
   private Label msglabel;

   public AwtLayoutDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtLayoutDemo  awtLayoutDemo = new AwtLayoutDemo();  
      awtLayoutDemo.showGridBagLayoutDemo();       
   }
      
   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      msglabel = new Label();
      msglabel.setAlignment(Label.CENTER);
      msglabel.setText("Welcome to TutorialsPoint AWT Tutorial.");

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showGridBagLayoutDemo(){
      headerLabel.setText("Layout in action: GridBagLayout");      

      Panel panel = new Panel();
      panel.setBackground(Color.darkGray);
      panel.setSize(300,300);
      GridBagLayout layout = new GridBagLayout();

      panel.setLayout(layout);        
      GridBagConstraints gbc = new GridBagConstraints();

      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.gridx = 0;
      gbc.gridy = 0;
      panel.add(new Button("Button 1"),gbc);

      gbc.gridx = 1;
      gbc.gridy = 0;
      panel.add(new Button("Button 2"),gbc); 

      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.ipady = 20;   
      gbc.gridx = 0;
      gbc.gridy = 1;
      panel.add(new Button("Button 3"),gbc); 

      gbc.gridx = 1;
      gbc.gridy = 1;       
      panel.add(new Button("Button 4"),gbc);  

      gbc.gridx = 0;
      gbc.gridy = 2;      
      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.gridwidth = 2;
      panel.add(new Button("Button 5"),gbc);  

      controlPanel.add(panel);

      mainFrame.setVisible(true);  
   }
}

Compile the program using command prompt. Go to D:/ > AWT and type the following command.

D:\AWT>javac com\tutorialspoint\gui\AwtlayoutDemo.java

If no error comes that means compilation is successful. Run the program using following command.

D:\AWT>java com.tutorialspoint.gui.AwtlayoutDemo

Verify the following output