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.
- a 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.
- a 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
| S.N. | Constructor & Description |
|---|---|
| 1 | GridBagLayout()Creates a grid bag layout manager. |
Class methods
| S.N. | Method & Description |
|---|---|
| 1 | void addLayoutComponent(Component comp, Object constraints)Adds the specified component to the layout, using the specified constraints object. |
| 2 | void addLayoutComponent(String name, Component comp)Adds the specified component with the specified name to the layout. |
| 3 | protected void adjustForGravity(GridBagConstraints constraints, Rectangle r)Adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads. |
| 4 | protected void AdjustForGravity(GridBagConstraints constraints, Rectangle r)This method is obsolete and supplied for backwards compatability only; new code should call adjustForGravity instead. |
| 5 | protected void arrangeGrid(Container parent)Lays out the grid. |
| 6 | protected void ArrangeGrid(Container parent)This method is obsolete and supplied for backwards compatability only; new code should call arrangeGrid instead. |
| 7 | GridBagConstraints getConstraints(Component comp)Gets the constraints for the specified component. |
| 8 | float getLayoutAlignmentX(Container parent)Returns the alignment along the x axis. |
| 9 | float getLayoutAlignmentY(Container parent)Returns the alignment along the y axis. |
| 10 | int[][] getLayoutDimensions()Determines column widths and row heights for the layout grid. |
| 11 | protected java.awt.GridBagLayoutInfo getLayoutInfo(Container parent, int sizeflag)Fills in an instance of GridBagLayoutInfo for the current set of managed children. |
| 12 | protected java.awt.GridBagLayoutInfo GetLayoutInfo(Container parent, int sizeflag)This method is obsolete and supplied for backwards compatability only; new code should call getLayoutInfo instead. |
| 13 | Point getLayoutOrigin()Determines the origin of the layout area, in the graphics coordinate space of the target container. |
| 14 | double[][] getLayoutWeights()Determines the weights of the layout grid’s columns and rows. |
| 15 | protected Dimension getMinSize(Container parent, java.awt.GridBagLayoutInfo info)Figures out the minimum size of the master based on the information from getLayoutInfo(). |
| 16 | protected Dimension GetMinSize(Container parent, java.awt.GridBagLayoutInfo info)This method is obsolete and supplied for backwards compatability only; new code should call getMinSize instead. |
| 17 | void invalidateLayout(Container target)Invalidates the layout, indicating that if the layout manager has cached information it should be discarded. |
| 18 | void layoutContainer(Container parent)Lays out the specified container using this grid bag layout. |
| 19 | Point location(int x, int y)Determines which cell in the layout grid contains the point specified by (x, y). |
| 20 | protected GridBagConstraints lookupConstraints(Component comp)Retrieves the constraints for the specified component. |
| 21 | Dimension maximumLayoutSize(Container target)Returns the maximum dimensions for this layout given the components in the specified target container. |
| 22 | Dimension minimumLayoutSize(Container parent)Determines the minimum size of the parent container using this grid bag layout. |
| 23 | Dimension preferredLayoutSize(Container parent)Determines the preferred size of the parent container using this grid bag layout. |
| 24 | void removeLayoutComponent(Component comp)Removes the specified component from this layout. |
| 25 | void setConstraints(Component comp, GridBagConstraints constraints)Sets the constraints for the specified component in this layout. |
| 26 | String toString()Returns a string representation of this grid bag layout’s values. |
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 > adglob> gui >AwtLayoutDemo.java
package com.adglob.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 Adglob 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\adglob\gui\AwtlayoutDemo.java
If no error comes that means compilation is successful. Run the program using following command.
D:\AWT>java com.adglob.gui.AwtlayoutDemo
Verify the following output
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