Java基础（Swing组件之密码框）

例如：

```handlebars
package Swing组件;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Demo10 extends JFrame {
    public Demo10(){
        setBounds(100,100,400,100);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        Container c =getContentPane();
        c.setLayout( new FlowLayout());

        JPasswordField jp = new JPasswordField();
        jp.setColumns(20); //设置密码框长度，20个字符
        jp.setFont(new Font("Arial",Font.BOLD,18)); //设置字体
        jp.setEchoChar('#');  //设置回旋字符
        c.add(jp);

        jp.addActionListener(new ActionListener() { //添加动作监听，回车
            @Override
            public void actionPerformed(ActionEvent e) {
                char ch[] = jp.getPassword();  //获取密码的字符数组
//                String str = new String(ch);
                System.out.println(ch);
                jp.setText("");    //输入后情况
                jp.requestFocus();     //获取光标
            }
        });

        c.add(jp);
        setVisible(true);
    }

    public static void main(String[] args) {
        new Demo10();
    }
}

运行结果: