java Swing组件setBounds()简单用法实例分析

package awtDemo;import java.awt.Dimension;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel;public class setBoundsDemo {  public static void main(String[] args) {    // TODO Auto-generated method stub    //设置panel的layout以及sieze    JPanel jpanel = new JPanel();    System.out.println("default PreferredSize is " + jpanel.getPreferredSize());    System.out.println("default Size is " + jpanel.getSize());    jpanel.setLayout(null);    System.out.println("In null layout, the PreferredSize is " + jpanel.getPreferredSize());    System.out.println("In null layout, the Size is " + jpanel.getSize());    jpanel.setPreferredSize(new Dimension(400, 400));    //添加按钮    JButton button11 = new JButton("setBounds");    JButton button12 = new JButton("setLocationAndSetSize");    button11.setBounds(20, 20, 100, 100);    button12.setLocation(250, 250);    button12.setSize(100, 100);    jpanel.add(button11);    jpanel.add(button12);    // 设置窗体属性    JFrame frame = new JFrame("setBoundsDemo");    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    frame.add(jpanel);    frame.pack();    frame.setLocationRelativeTo(null);    frame.setVisible(true);  }}