編寫程序，利用JtextField和JpasswordField分別接收用戶輸入的用戶名和密碼，並對用戶輸入的密碼進行檢驗。對於每個用戶名有三次密碼輸入機會。

package beizi;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.BorderLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JTextField;
import java.awt.Color;
import javax.swing.JCheckBox;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import javax.swing.JTextPane;
import java.awt.TextArea;
import java.awt.Label;
import javax.swing.JPasswordField;
import javax.swing.JOptionPane;

public class test {

	private JFrame frame;
	private JPasswordField passwordField;
	private JTextField textField;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					test window = new test();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the application.
	 */
	public test() {
		initialize();
		
	}
	/**
	 * Judge the pwd and username
	 */
	public void judge() {
		
	}

	/**
	 * Initialize the contents of the frame.
	 */
	private void initialize() {
		frame = new JFrame();
		frame.setBounds(100, 100, 450, 300);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
		

		Label label_2 = new Label("login");//login
		label_2.setBounds(141, 31, 139, 23);
		frame.getContentPane().add(label_2);
		
		
		JButton btnNewButton = new JButton("\u767B\u5F55");//登錄
		btnNewButton.setBounds(168, 198, 93, 23);
		btnNewButton.setBackground(Color.LIGHT_GRAY);
		btnNewButton.addActionListener(new ActionListener() {
			int i = 3;
			public void actionPerformed(ActionEvent arg0) {
				String usr=textField.getText();
				String pwd=passwordField.getText();
				
				while(i!=0) {
					i--;
					if(usr.equals("123456")&pwd.equals("abc123")) {
					    JOptionPane.showMessageDialog(null,  "登陸成功！歡迎徐小白同學~");
					    break;
				     }
					else {
						JOptionPane.showMessageDialog(null, "賬戶或密碼錯誤，你還有"+(i)+"次機會");
						break;
					}
				}
				if(i==0) {
					System.exit(0);
				}
			}
		});
		frame.getContentPane().add(btnNewButton);
		
		Label label = new Label("\u5B66\u53F7\uFF1A");//學號
		label.setBounds(140, 73, 34, 23);
		frame.getContentPane().add(label);
		
		Label label_1 = new Label("\u5BC6\u7801\uFF1A");//密碼
		label_1.setBounds(140, 121, 34, 23);
		frame.getContentPane().add(label_1);
		
		passwordField = new JPasswordField();
		passwordField.setBounds(182, 123, 79, 21);
		frame.getContentPane().add(passwordField);

		textField = new JTextField();
		textField.setBounds(182, 73, 79, 21);
		frame.getContentPane().add(textField);
		textField.setColumns(10);
		
	}
	
}

醜陋的效果，，，：

java登錄圖形界面