レイアウトマネージャ

import javax.swing.JFrame; import javax.swing.JButton; import java.awt.FlowLayout; import java.awt.Container;  public class LayoutExample extends JFrame {     public LayoutExample() {         this.setTitle("FlowLayoutDemo");         // get the top-level container in the Frame (= Window)         Container contentPane = this.getContentPane();          // set the layout of this container         contentPane.setLayout(new FlowLayout());          // add buttons in this container         this.add((new JButton("Button 1")));         this.add((new JButton("Button 2")));         this.add((new JButton("Button 3")));         this.add((new JButton("Long-Named Button 4")));         this.add((new JButton("5")));          // unrelated, exit the application when clicking on the          // right close-button         this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);     }      public static void main(String[] args) {         LayoutExample example = new LayoutExample();         example.setVisible(true);     } }