SWING - GroupLayout Class

Introduction

The class GroupLayout hierarchically groups the components in order to position them in a Container.

Class Declaration

Following is the declaration for javax.swing.GroupLayout class −

public class GroupLayout
   extends Object
      implements LayoutManager2

Field

Following are the fields for javax.swing.GroupLayout class −

static int DEFAULT_SIZE − Indicates the size from the component or the gap should be used for a particular range value.
static int PREFERRED_SIZE − Indicates the preferred size from the component or the gap should be used for a particular range value.

Class Constructors

Sr.No.	Constructor & Description
1	GroupLayout(Container host) Creates a GroupLayout for the specified Container.

Class Methods

Sr.No.	Method & Description
1	void addLayoutComponent(Component component, Object constraints) Notification that a Component has been added to the parent container.
2	void addLayoutComponent(String name, Component component) Notification that a Component has been added to the parent container.
3	GroupLayout.ParallelGroup createBaselineGroup(boolean resizable, boolean anchorBaselineToTop) Creates and returns a ParallelGroup that aligns it's elements along the baseline.
4	GroupLayout.ParallelGroup createParallelGroup() Creates and returns a ParallelGroup with an alignment of Alignment.LEADING.
5	GroupLayout.ParallelGroup createParallelGroup(GroupLayout.Alignment alignment) Creates and returns a ParallelGroup with the specified alignment.
6	GroupLayout.ParallelGroup createParallelGroup(GroupLayout.Alignment alignment, boolean resizable) Creates and returns a ParallelGroup with the specified alignment and resize behavior.
7	GroupLayout.SequentialGroup createSequentialGroup() Creates and returns a SequentialGroup.
8	boolean getAutoCreateContainerGaps() Returns true if the gaps between the container and the components that border the container are automatically created.
9	boolean getAutoCreateGaps() Returns true if the gaps between the components are automatically created.
10	boolean getHonorsVisibility() Returns whether the component visiblity is considered when sizing and positioning the components.
11	float getLayoutAlignmentX(Container parent) Returns the alignment along the x axis.
12	float getLayoutAlignmentY(Container parent) Returns the alignment along the y axis.
13	LayoutStyle getLayoutStyle() Returns the LayoutStyle used for calculating the preferred gap between the components.
14	void invalidateLayout(Container parent) Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
15	void layoutContainer(Container parent) Lays out the specified container.
16	void linkSize(Component... components) Forces the specified components to have the same size regardless of their preferred, minimum, or maximum sizes.
17	void linkSize(int axis, Component... components) Forces the specified components to have the same size along the specified axis regardless of their preferred, minimum, or maximum sizes.
18	Dimension maximumLayoutSize(Container parent) Returns the maximum size for the specified container.
19	Dimension minimumLayoutSize(Container parent) Returns the minimum size for the specified container.
20	Dimension preferredLayoutSize(Container parent) Returns the preferred size for the specified container.
21	void removeLayoutComponent(Component component) Notifies that a Component has been removed from the parent container.
22	void replace(Component existingComponent, Component newComponent) Replaces an existing component with a new one.
23	void setAutoCreateContainerGaps(boolean autoCreateContainerPadding) Sets whether a gap between the container and the components that touch the border of the container should automatically be created.
24	void setAutoCreateGaps(boolean autoCreatePadding) Sets whether a gap between the components should automatically be created.
25	void setHonorsVisibility(boolean honorsVisibility) Sets whether the component visiblity is considered when sizing and positioning the components.
26	void setHonorsVisibility(Component component, Boolean honorsVisibility) Sets whether the component's visiblity is considered for sizing and positioning.
27	void setHorizontalGroup(GroupLayout.Group group) Sets the Group that positions and sizes the components along the horizontal axis.
28	void setLayoutStyle(LayoutStyle layoutStyle) Sets the LayoutStyle used to calculate the preferred gaps between the components.
29	void setVerticalGroup(GroupLayout.Group group) Sets the Group that positions and sizes the components along the vertical axis.
30	String toString() Returns a string representation of this GroupLayout.

Methods Inherited

This class inherits methods from the following class −

java.lang.Object

GroupLayout Example

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

SwingLayoutDemo.java

package com.tutorialspoint.gui;

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

public class SwingLayoutDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;
   private JLabel msglabel;

   public SwingLayoutDemo(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingLayoutDemo swingLayoutDemo = new SwingLayoutDemo();  
      swingLayoutDemo.showGroupLayoutDemo();       
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java SWING Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));

      headerLabel = new JLabel("",JLabel.CENTER );
      statusLabel = new JLabel("",JLabel.CENTER);        
      statusLabel.setSize(350,100);
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private void showGroupLayoutDemo(){
      headerLabel.setText("Layout in action: GroupLayout");      
      JPanel panel = new JPanel();
      
      // panel.setBackground(Color.darkGray);
      panel.setSize(200,200);
      GroupLayout layout = new GroupLayout(panel);
      layout.setAutoCreateGaps(true);
      layout.setAutoCreateContainerGaps(true);
      
      JButton btn1 = new JButton("Button 1");
      JButton btn2 = new JButton("Button 2");
      JButton btn3 = new JButton("Button 3");

      layout.setHorizontalGroup(layout.createSequentialGroup()
         .addComponent(btn1)
         .addGroup(layout.createSequentialGroup()
         .addGroup(layout.createParallelGroup(
         GroupLayout.Alignment.LEADING)
         .addComponent(btn2)
         .addComponent(btn3))));
   
      layout.setVerticalGroup(layout.createSequentialGroup()
         .addComponent(btn1)
         .addComponent(btn2)
         .addComponent(btn3));
      
      panel.setLayout(layout);        
      controlPanel.add(panel);
      mainFrame.setVisible(true);  
   }
}

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

D:\SWING>javac com\tutorialspoint\gui\SwingLayoutDemo.java

If no error occurs, it means the compilation is successful. Run the program using the following command.

D:\SWING>java com.tutorialspoint.gui.SwingLayoutDemo

Verify the following output.

swing_layouts.htm