Java Tutorial/Swing/GridBagLayout

Associate the gridbag constraints with the component

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    Container container = frame.getContentPane();
    GridBagLayout gbl = new GridBagLayout();
    container.setLayout(gbl);
    
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx = 1;
    gbc.gridy = 1;
    
    JButton component = new JButton("a");
    
    
    gbl.setConstraints(component, gbc);
    container.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Create and set a gridbag layout and how to set gridbag constraints

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    Container container = frame.getContentPane();
    GridBagLayout gbl = new GridBagLayout();
    container.setLayout(gbl);
    // Place a component at cell location (1,1)
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx = 1;
    gbc.gridy = 1;
    
    JButton component = new JButton("a");
    
    // Associate the gridbag constraints with the component
    gbl.setConstraints(component, gbc);
    container.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Getting the Number of Rows and Columns of Cells in a GridBagLayout

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    Container container = frame.getContentPane();
    GridBagLayout gbl = new GridBagLayout();
    container.setLayout(gbl);
    GridBagConstraints gbc = new GridBagConstraints();
    JButton component1 = new JButton("a");
    JButton component2 = new JButton("b");
    gbc.gridx = 1;
    gbc.gridy = 1;
    gbl.setConstraints(component1, gbc);
    container.add(component1);
    gbc.gridx = 0;
    gbc.gridy = 0;
    gbl.setConstraints(component2, gbc);
    container.add(component2);
    container.add(component1);
    container.add(component2);
    frame.pack();
    frame.setVisible(true);
    gbl.layoutContainer(container);
    int[][] dim = gbl.getLayoutDimensions();
    int cols = dim[0].length;
    int rows = dim[1].length;
    System.out.println(cols);
    System.out.println(rows);
  }
}

Make the component only stretch horizontally

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.fill = GridBagConstraints.HORIZONTAL;
    gbl.setConstraints(component, gbc);
    frame.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Make the component only stretch vertically

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.fill = GridBagConstraints.VERTICAL;
    gbl.setConstraints(component, gbc);
    frame.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Make the component on stretchable

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    
    GridBagConstraints gbc = new GridBagConstraints();
    
    
    gbc.fill = GridBagConstraints.NONE;
    
    gbl.setConstraints(component, gbc);
    frame.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Make the component stretch in both directions

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.fill = GridBagConstraints.BOTH;
    gbl.setConstraints(component, gbc);
    frame.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Making a GridBagLayout Fill the Container

import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    frame.add(new JButton("1"));
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    double[][] weights = gbl.getLayoutWeights();
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < weights[i].length; j++) {
        weights[i][j] = 1;
      }
    }
    gbl.columnWeights = weights[0];
    gbl.rowWeights = weights[1];
    frame.pack();
    frame.setVisible(true);
  }
}

Place a component at (ith a column weight 1 and a row weight of 2

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx = 0;
    gbc.gridy = 1;
    gbc.weightx = 1;
    gbc.weighty = 2;
    gbl.setConstraints(component, gbc);

    frame.pack();
    frame.setVisible(true);
  }
}

Place a component at cell location (1,1)

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    Container container = frame.getContentPane();
    GridBagLayout gbl = new GridBagLayout();
    container.setLayout(gbl);
    
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.gridx = 1;
    gbc.gridy = 1;
    
    JButton component = new JButton("a");
    
    
    gbl.setConstraints(component, gbc);
    container.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Positioning a component in the center of other component using GridbagLayout

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Label;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
  public static void main(String[] argv) {
    JFrame demo = new JFrame("GridBag demo, to center a component");
    JPanel parentPanel = new JPanel();
    GridBagLayout gridbag = new GridBagLayout();
    GridBagConstraints constraints = new GridBagConstraints();
    constraints.fill = GridBagConstraints.CENTER;
    gridbag.setConstraints(parentPanel, constraints);
    parentPanel.setLayout(gridbag);
    Label centerLabel = new Label(" AAA...");
    parentPanel.add(centerLabel);
    demo.add(parentPanel);
    demo.setSize(500, 500);
    demo.setVisible(true);
  }
}

Positions five components within a container, using weights, fill, and relative positioning

/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */

/*
 * ContainerEventDemo.java requires no other files.
 */
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ContainerEvent;
import java.awt.event.ContainerListener;
import java.util.Vector;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class ContainerEventDemo extends JPanel implements ContainerListener, ActionListener {
  JTextArea display;
  JPanel buttonPanel;
  JButton addButton, removeButton, clearButton;
  Vector<JButton> buttonList;
  static final String ADD = "add";
  static final String REMOVE = "remove";
  static final String CLEAR = "clear";
  static final String newline = "\n";
  public ContainerEventDemo() {
    super(new GridBagLayout());
    GridBagLayout gridbag = (GridBagLayout) getLayout();
    GridBagConstraints c = new GridBagConstraints();
    // Initialize an empty list of buttons.
    buttonList = new Vector<JButton>(10, 10);
    // Create all the components.
    addButton = new JButton("Add a button");
    addButton.setActionCommand(ADD);
    addButton.addActionListener(this);
    removeButton = new JButton("Remove a button");
    removeButton.setActionCommand(REMOVE);
    removeButton.addActionListener(this);
    buttonPanel = new JPanel(new GridLayout(1, 1));
    buttonPanel.setPreferredSize(new Dimension(200, 75));
    buttonPanel.addContainerListener(this);
    display = new JTextArea();
    display.setEditable(false);
    JScrollPane scrollPane = new JScrollPane(display);
    scrollPane.setPreferredSize(new Dimension(200, 75));
    clearButton = new JButton("Clear text area");
    clearButton.setActionCommand(CLEAR);
    clearButton.addActionListener(this);
    c.fill = GridBagConstraints.BOTH; // Fill entire cell.
    c.weighty = 1.0; // Button area and message area have equal height.
    c.gridwidth = GridBagConstraints.REMAINDER; // end of row
    gridbag.setConstraints(scrollPane, c);
    add(scrollPane);
    c.weighty = 0.0;
    gridbag.setConstraints(clearButton, c);
    add(clearButton);
    c.weightx = 1.0; // Add/remove buttons have equal width.
    c.gridwidth = 1; // NOT end of row
    gridbag.setConstraints(addButton, c);
    add(addButton);
    c.gridwidth = GridBagConstraints.REMAINDER; // end of row
    gridbag.setConstraints(removeButton, c);
    add(removeButton);
    c.weighty = 1.0; // Button area and message area have equal height.
    gridbag.setConstraints(buttonPanel, c);
    add(buttonPanel);
    setPreferredSize(new Dimension(400, 400));
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
  }
  public void componentAdded(ContainerEvent e) {
    displayMessage(" added to ", e);
  }
  public void componentRemoved(ContainerEvent e) {
    displayMessage(" removed from ", e);
  }
  void displayMessage(String action, ContainerEvent e) {
    display.append(((JButton) e.getChild()).getText() + " was" + action
        + e.getContainer().getClass().getName() + newline);
    display.setCaretPosition(display.getDocument().getLength());
  }
  /*
   * This could have been implemented as two or three classes or objects, for
   * clarity.
   */
  public void actionPerformed(ActionEvent e) {
    String command = e.getActionCommand();
    if (ADD.equals(command)) {
      JButton newButton = new JButton("JButton #" + (buttonList.size() + 1));
      buttonList.addElement(newButton);
      buttonPanel.add(newButton);
      buttonPanel.revalidate(); // Make the button show up.
    } else if (REMOVE.equals(command)) {
      int lastIndex = buttonList.size() - 1;
      try {
        JButton nixedButton = buttonList.elementAt(lastIndex);
        buttonPanel.remove(nixedButton);
        buttonList.removeElementAt(lastIndex);
        buttonPanel.revalidate(); // Make the button disappear.
        buttonPanel.repaint(); // Make the button disappear.
      } catch (ArrayIndexOutOfBoundsException exc) {
      }
    } else if (CLEAR.equals(command)) {
      display.setText("");
    }
  }
  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("ContainerEventDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Create and set up the content pane.
    JComponent newContentPane = new ContainerEventDemo();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);
    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }
  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application"s GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}

Setting Stretchyness of a GridBagLayout Using Fill

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(component);
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);
    
    GridBagConstraints gbc = new GridBagConstraints();
    
    // Make the component on stretchable
    gbc.fill = GridBagConstraints.NONE;
    
    gbl.setConstraints(component, gbc);
    frame.add(component);
    frame.pack();
    frame.setVisible(true);
  }
}

Setting the Location of a Component in a GridBagLayout

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    Container container = frame.getContentPane();
    GridBagLayout gbl = new GridBagLayout();
    container.setLayout(gbl);
    GridBagConstraints gbc = new GridBagConstraints();
    JButton component1 = new JButton("a");
    JButton component2 = new JButton("b");
    gbc.gridx = 1;
    gbc.gridy = 1;
    gbl.setConstraints(component1, gbc);
    container.add(component1);
    gbc.gridx = 0;
    gbc.gridy = 0;
    gbl.setConstraints(component2, gbc);
    container.add(component2);
    container.add(component1);
    container.add(component2);
    frame.pack();
    frame.setVisible(true);
  }
}

Setting the Space around a Component Within the Cell of the GridBagLayout Using Insets

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    JButton component = new JButton("1");
    frame.add(new JButton("2"));
    frame.add(new JButton("3"));
    frame.add(new JButton("4"));
    frame.add(new JButton("5"));
    frame.add(component);
    frame.add(new JButton("6"));
    frame.add(new JButton("7"));
    frame.add(new JButton("8"));
    frame.add(new JButton("9"));
    frame.add(new JButton("0"));
    
    gbl.layoutContainer(frame);
    GridBagConstraints gbc = new GridBagConstraints();
    int top = 20;
    int left = 20;
    int bottom = 2;
    int right = 40;
    gbc.insets = new Insets(top, left, bottom, right);
    gbl.setConstraints(component, gbc);

    frame.pack();
    frame.setVisible(true);
  }
}

Setting the Stretchyness of Rows and Columns in a GridBagLayout Using Layout Weights

import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Main {
  public static void main(String[] argv) throws Exception {
    JFrame frame = new JFrame();
    GridBagLayout gbl = new GridBagLayout();
    frame.setLayout(gbl);
    frame.add(new JButton("1"));
    frame.add(new JButton("2"));
    gbl.layoutContainer(frame);

    gbl.columnWeights = new double[]{0.0f, 1.0f, 2.0f};
    gbl.rowWeights = new double[]{0.0f, 1.0f};
    frame.pack();
    frame.setVisible(true);
  }
}

Uses many features

- weights, insets, internal padding, horizontal fill, exact cell positioning, multi-column cells, and anchoring (component positioning within a cell)

/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */

/*
 * GridBagLayoutDemo.java requires no other files.
 */
import java.awt.ruponentOrientation;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
public class GridBagLayoutDemo {
  final static boolean shouldFill = true;
  final static boolean shouldWeightX = true;
  final static boolean RIGHT_TO_LEFT = false;
  public static void addComponentsToPane(Container pane) {
    if (RIGHT_TO_LEFT) {
      pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    }
    JButton button;
    pane.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    if (shouldFill) {
      // natural height, maximum width
      c.fill = GridBagConstraints.HORIZONTAL;
    }
    button = new JButton("Button 1");
    if (shouldWeightX) {
      c.weightx = 0.5;
    }
    c.gridx = 0;
    c.gridy = 0;
    pane.add(button, c);
    button = new JButton("Button 2");
    c.gridx = 1;
    c.gridy = 0;
    pane.add(button, c);
    button = new JButton("Button 3");
    c.gridx = 2;
    c.gridy = 0;
    pane.add(button, c);
    button = new JButton("Long-Named Button 4");
    c.ipady = 40; // make this component tall
    c.weightx = 0.0;
    c.gridwidth = 3;
    c.gridx = 0;
    c.gridy = 1;
    pane.add(button, c);
    button = new JButton("5");
    c.ipady = 0; // reset to default
    c.weighty = 1.0; // request any extra vertical space
    c.anchor = GridBagConstraints.PAGE_END; // bottom of space
    c.insets = new Insets(10, 0, 0, 0); // top padding
    c.gridx = 1; // aligned with button 2
    c.gridwidth = 2; // 2 columns wide
    c.gridy = 2; // third row
    pane.add(button, c);
  }
  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("GridBagLayoutDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Set up the content pane.
    addComponentsToPane(frame.getContentPane());
    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }
  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application"s GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}

Using a GridBagLayout Manager

1. GridBagLayout is the most complex and most flexible of the layout managers.
2. Elements are arranged in a rectangular grid.
3. Elements can have different sizes and can occupy multiple rows or columns.
4. The position and behavior of each element is specified by an instance of the GridBagConstraints class.

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.border.Border;
public class TryGridBagLayout {
  static JFrame aWindow = new JFrame("This is a Gridbag Layout");
  public static void main(String[] args) {
    aWindow.setBounds(30, 30, 300, 300);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    GridBagLayout gridbag = new GridBagLayout();
    GridBagConstraints constraints = new GridBagConstraints();
    aWindow.getContentPane().setLayout(gridbag);
    constraints.weightx = constraints.weighty = 10.0;
    constraints.fill = constraints.BOTH;
    addButton(" Press ", constraints, gridbag);
    constraints.gridwidth = constraints.REMAINDER;
    addButton("GO", constraints, gridbag);
    aWindow.setVisible(true);
  }
  static void addButton(String label, GridBagConstraints constraints, GridBagLayout layout) {
    Border edge = BorderFactory.createRaisedBevelBorder();
    JButton button = new JButton(label);
    button.setBorder(edge);
    layout.setConstraints(button, constraints);
    aWindow.getContentPane().add(button);
  }
}