BoxLayout layout manager in action. The JFrame uses a BorderLayout to position two JPanels, one above the other. The two JPanels both use the BoxLayout manager to position a number of buttons. The difference is that the top JPanel uses the PAGE_AXIS option to position the buttons vertically whereas the bottom JPanel uses the LINE_AXIS to position the buttons horizontally.The
BoxLayout is similar to the GridLayout layout managers except it only ever has one row or one column.The article that goes with this example is Using the Box Layout. For more information on other layout managers have a look at An Overview of Layout Managers.
import java.awt.EventQueue;import java.awt.BorderLayout;import java.awt.Color;import javax.swing.BorderFactory;import javax.swing.border.Border;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JButton;import java.awt.Container;import javax.swing.BoxLayout;public class BoxLayoutExample {//Note: Typically the main method will be in a//separate class. As this is a simple one class//example it's all in the one class.public static void main(String[] args) {//Use the event dispatch thread for Swing components EventQueue.invokeLater(new Runnable() { @Override public void run() {new BoxLayoutExample();} });}public BoxLayoutExample(){JFrame guiFrame = new JFrame();//make sure the program exits when the frame closesguiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);guiFrame.setTitle("FlowLayout Example");guiFrame.setSize(400,300);//This will center the JFrame in the middle of the screenguiFrame.setLocationRelativeTo(null);guiFrame.setLayout(new BorderLayout());//creating a border to highlight the JPanel areasBorder outline = BorderFactory.createLineBorder(Color.black);JPanel pageAxisPanel = new JPanel();pageAxisPanel.setBorder(outline);pageAxisPanel.setLayout(new BoxLayout(pageAxisPanel, BoxLayout.PAGE_AXIS));//Add some buttonsfor (int i=1;i<6;i++){addButton(pageAxisPanel, String.valueOf(i));}JPanel lineAxisPanel = new JPanel();lineAxisPanel.setLayout(new BoxLayout(lineAxisPanel, BoxLayout.LINE_AXIS));lineAxisPanel.setBorder(outline);//Add some buttonsfor (int i=1;i<6;i++){addButton(lineAxisPanel, String.valueOf(i));}guiFrame.add(pageAxisPanel,BorderLayout.NORTH);guiFrame.add(lineAxisPanel,BorderLayout.SOUTH);guiFrame.setVisible(true);}//All the buttons are following the same pattern//so create them all in one place.private void addButton(Container parent, String name){JButton but = new JButton(name);but.setActionCommand(name);parent.add(but);}}