Java Tutorial/Swing/GridLayout

Creating Rows of Buttons

import java.awt.Container;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class GridTest extends JFrame {
  public static void main(String[] args) {
    int rows = 2;
    int cols = 3;
    GridTest gt = new GridTest(rows, cols);
    gt.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    gt.pack();
    gt.setVisible(true);
  }
  public GridTest(int rows, int cols) {
    Container pane = getContentPane();
    pane.setLayout(new GridLayout(rows, cols));
    for (int i = 0; i < 20; i++) {
      JButton button = new JButton(Integer.toString(i + 1));
      pane.add(button);
    }
  }
}

How to Use GridLayout

1. A GridLayout places components in a grid of cells.
2. Each component takes all the available space within its cell.
3. Each cell is exactly the same size.
4. Components are added to the layout from left to right, top to bottom.
5. new GridLayout(3, 4): three rows and four columns,
6. Setting the number of rows or columns to be zero, and the layout will grow without bounds in the direction with a zero setting.

The GridLayout class has two constructors:

public GridLayout(int rows, int columns)
    public GridLayout(int rows, int columns, int horizontalGap, int verticalGap)

Laying Out Components in a Grid

import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
public class Main {
  public static void main(String[] argv) throws Exception {
    JButton component1 = new JButton();
    JButton component2 = new JButton();
    
    int rows = 2;
    int cols = 2;
    JPanel panel = new JPanel(new GridLayout(rows, cols));
    panel.add(component1);
    panel.add(component2);
  }
}

Sample GridLayout Application

import java.awt.Container;
import java.awt.Font;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class GridSizeTest extends JFrame {
  public static void main(String[] args) {
    GridSizeTest gst = new GridSizeTest();
    gst.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    gst.pack();
    gst.setVisible(true);
  }
  public GridSizeTest() {
    Container pane = getContentPane();
    pane.setLayout(new GridLayout(2, 2));
    JButton button = new JButton("First");
    pane.add(button);
    button = new JButton("Second with a very long name");
    pane.add(button);
    button = new JButton("Hi");
    button.setFont(new Font("Courier", Font.PLAIN, 36));
    pane.add(button);
    button = new JButton("There");
    pane.add(button);
  }
}

Use a 1x1 grid to make a component as large as possible

/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
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 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
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 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
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 * 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
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 * POSSIBILITY OF SUCH DAMAGES.
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import java.awt.Color;
import java.awt.ruponent;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
/* ComboBoxDemo2.java requires no other files. */
public class ComboBoxDemo2 extends JPanel implements ActionListener {
  static JFrame frame;
  JLabel result;
  String currentPattern;
  public ComboBoxDemo2() {
    setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
    String[] patternExamples = { "dd MMMMM yyyy", "dd.MM.yy", "MM/dd/yy",
        "yyyy.MM.dd G "at" hh:mm:ss z", "EEE, MMM d, ""yy", "h:mm a", "H:mm:ss:SSS", "K:mm a,z",
        "yyyy.MMMMM.dd GGG hh:mm aaa" };
    currentPattern = patternExamples[0];
    // Set up the UI for selecting a pattern.
    JLabel patternLabel1 = new JLabel("Enter the pattern string or");
    JLabel patternLabel2 = new JLabel("select one from the list:");
    JComboBox patternList = new JComboBox(patternExamples);
    patternList.setEditable(true);
    patternList.addActionListener(this);
    // Create the UI for displaying result.
    JLabel resultLabel = new JLabel("Current Date/Time", JLabel.LEADING); // ==
                                                                          // LEFT
    result = new JLabel(" ");
    result.setForeground(Color.black);
    result.setBorder(BorderFactory.createCompoundBorder(
        BorderFactory.createLineBorder(Color.black), BorderFactory.createEmptyBorder(5, 5, 5, 5)));
    // Lay out everything.
    JPanel patternPanel = new JPanel();
    patternPanel.setLayout(new BoxLayout(patternPanel, BoxLayout.PAGE_AXIS));
    patternPanel.add(patternLabel1);
    patternPanel.add(patternLabel2);
    patternList.setAlignmentX(Component.LEFT_ALIGNMENT);
    patternPanel.add(patternList);
    JPanel resultPanel = new JPanel(new GridLayout(0, 1));
    resultPanel.add(resultLabel);
    resultPanel.add(result);
    patternPanel.setAlignmentX(Component.LEFT_ALIGNMENT);
    resultPanel.setAlignmentX(Component.LEFT_ALIGNMENT);
    add(patternPanel);
    add(Box.createRigidArea(new Dimension(0, 10)));
    add(resultPanel);
    setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    reformat();
  } // constructor
  public void actionPerformed(ActionEvent e) {
    JComboBox cb = (JComboBox) e.getSource();
    String newSelection = (String) cb.getSelectedItem();
    currentPattern = newSelection;
    reformat();
  }
  /** Formats and displays today"s date. */
  public void reformat() {
    Date today = new Date();
    SimpleDateFormat formatter = new SimpleDateFormat(currentPattern);
    try {
      String dateString = formatter.format(today);
      result.setForeground(Color.black);
      result.setText(dateString);
    } catch (IllegalArgumentException iae) {
      result.setForeground(Color.red);
      result.setText("Error: " + iae.getMessage());
    }
  }
  /**
   * 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("ComboBoxDemo2");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // Create and set up the content pane.
    JComponent newContentPane = new ComboBoxDemo2();
    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();
      }
    });
  }
}

Uses a 2-column grid.

import java.awt.ruponentOrientation;
import java.awt.Container;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class GridLayoutDemo {
  public final static boolean RIGHT_TO_LEFT = false;
  public static void addComponentsToPane(Container pane) {
    if (RIGHT_TO_LEFT) {
      pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    }
    pane.setLayout(new GridLayout(0, 2));
    pane.add(new JButton("Button 1"));
    pane.add(new JButton("Button 2"));
    pane.add(new JButton("Button 3"));
    pane.add(new JButton("Long-Named Button 4"));
    pane.add(new JButton("5"));
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("GridLayoutDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    addComponentsToPane(frame.getContentPane());
    frame.pack();
    frame.setVisible(true);
  }
}

Using a GridLayout Manager

Place components in a grid

GridLayout()   Creates a grid layout manager 
    
    GridLayout(int rows, int cols)
    GridLayout(int rows, int cols, int hgap, int vgap)