话说内部类与匿名内部类、正则表达式检验计算器输入（00）处理方式、设置JRame背景颜色实例

package com.meteor.regx;

import java.awt.FlowLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.regex.Pattern;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

/**
*
* @author Xuyunfei
* 本实例程序是为测试计算器输入无效的数字（00······）编写
*其中涉及了内部类以及匿名内部类、正则表达式、事件监听的用法
*/
public class TestFieldInput extends JFrame {

/**
*
*/
private static final long serialVersionUID = 1L;

@SuppressWarnings("unused")
private final int width;
@SuppressWarnings("unused")
private final int height;
@SuppressWarnings("unused")
private Pattern p;
private String regx = "^0+";
private JTextField jtx;

public static void main(String[] args) {
new TestFieldInput(300, 400);
}

private TestFieldInput(int width, int height) {
this.width = width;
this.height = height;

// this.getContentPane().setLayout(new FlowLayout());
this.setLayout(new FlowLayout());
this.setLocation(300, 200);
this.setSize(width, height);
jtx = new JTextField("0.0", 15);
jtx.addFocusListener(new TextFocusMoniter());
/*
* JAVA SWING中JFRAME构造的时候为默认添加一个RootPane
* 默认的布局管理器为BORDERLayout
* 通常我们在调用使用下面一条语句设置背景颜色时是看不到的
* 这里其实我们设置的是FRAME，被ROOTPANE挡住了看不到
* 这时可用下面这条语句 this.getContentPane().setBackground(Color.blue)
* 达到想要的效果
*/
// this.setBackground(Color.red);
// this.getContentPane().setBackground(Color.blue);
this.add(jtx);

this.setResizable(false);
this.setVisible(true);
this.pack();
// this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//这是为使用匿名内而写的匿名内，上一行语句可达到同样的结果
this.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
setVisible(false);
System.exit(-1);
}
});
}

public void inputMatches() {
p = Pattern.compile(regx, Pattern.CASE_INSENSITIVE);

if (this.jtx.getText() == null || this.jtx.getText().equals("")) {
return;
}

if (Pattern.matches(regx, this.jtx.getText())) {
JOptionPane.showMessageDialog(null, "你输入了不正确的数据，请重新输入！！！");
this.jtx.setText("输入的数字没有任何意义！");
} else {
return;
}
}

private class TextFocusMoniter extends FocusAdapter {
@Override
public void focusGained(FocusEvent e) {
inputMatches();
}
}
}