java空指针不知道错哪急救！！！

程序员文章站 2022-09-06 12:33:01

Exception in thread “AWT-EventQueue-0” java.lang.NullPointerException
at wt.views.LoginView.loginUserActionPerformed(LoginView.java:156)
at wt.views.LoginView.access$0(LoginView.java:154)
at wt.views.LoginView $2.actionPerformed(LoginView.java:86) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$ Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue $3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$ JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue $4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$ JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

package wt.views;

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;

import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.border.EmptyBorder;

import wt.dao.daouser;
import wt.model.User;
import wt.tool.tool;
import wt.tool.toolstring;

@SuppressWarnings("serial")
public class LoginView extends JFrame {


	
	private tool dbUtil = new tool();
	private daouser userDao = new daouser();

	private JPanel contentPane;
	private JTextField text_userName;
	private JPasswordField text_password;
	private JLabel text_name;
	private JPasswordField text_pass;

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

	/**
	 * Create the frame.
	 */
	public LoginView() {
		setTitle("\u56FE\u4E66\u7BA1\u7406\u7CFB\u7EDF-\u7528\u6237\u767B\u5F55");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 564, 452);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		
		JLabel lblNewLabel = new JLabel("\u7528\u6237\u540D\uFF1A");
		lblNewLabel.setFont(new Font("宋体", Font.PLAIN, 19));
		
		text_userName = new JTextField();
		text_userName.setFont(new Font("宋体", Font.PLAIN, 19));
		text_userName.setColumns(10);
		
		JLabel lblNewLabel_1 = new JLabel(" \u56FE\u4E66\u7BA1\u7406\u7CFB\u7EDF");
		lblNewLabel_1.setFont(new Font("宋体", Font.BOLD, 40));
		lblNewLabel_1.setIcon(new ImageIcon(LoginView.class.getResource("/picture/logo.png")));
		
		JLabel lblNewLabel_2 = new JLabel("\u5BC6  \u7801\uFF1A");
		lblNewLabel_2.setFont(new Font("宋体", Font.PLAIN, 19));
		
		text_password = new JPasswordField();
		text_password.setFont(new Font("宋体", Font.PLAIN, 19));
		
		JButton btnNewButton = new JButton("\u767B\u5F55");
		btnNewButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				loginUserActionPerformed(e);
			}


		});
		btnNewButton.setIcon(new ImageIcon(LoginView.class.getResource("/picture/login.png")));
		btnNewButton.setFont(new Font("宋体", Font.PLAIN, 19));
		
		JButton btnNewButton_1 = new JButton("\u6CE8\u518C");
		btnNewButton_1.setIcon(new ImageIcon(LoginView.class.getResource("/picture/addUser.png")));
		btnNewButton_1.setFont(new Font("宋体", Font.PLAIN, 19));
		GroupLayout gl_contentPane = new GroupLayout(contentPane);
		gl_contentPane.setHorizontalGroup(
			gl_contentPane.createParallelGroup(Alignment.LEADING)
				.addGroup(gl_contentPane.createSequentialGroup()
					.addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
						.addGroup(gl_contentPane.createSequentialGroup()
							.addGap(120)
							.addComponent(lblNewLabel)
							.addGap(15)
							.addComponent(text_userName, GroupLayout.PREFERRED_SIZE, 177, GroupLayout.PREFERRED_SIZE))
						.addGroup(gl_contentPane.createSequentialGroup()
							.addGap(121)
							.addComponent(lblNewLabel_2)
							.addGap(13)
							.addComponent(text_password, GroupLayout.PREFERRED_SIZE, 179, GroupLayout.PREFERRED_SIZE))
						.addGroup(gl_contentPane.createSequentialGroup()
							.addGap(119)
							.addComponent(btnNewButton)
							.addGap(98)
							.addComponent(btnNewButton_1))
						.addGroup(gl_contentPane.createSequentialGroup()
							.addGap(73)
							.addComponent(lblNewLabel_1, GroupLayout.PREFERRED_SIZE, 382, GroupLayout.PREFERRED_SIZE)))
					.addContainerGap(81, Short.MAX_VALUE))
		);
		gl_contentPane.setVerticalGroup(
			gl_contentPane.createParallelGroup(Alignment.LEADING)
				.addGroup(gl_contentPane.createSequentialGroup()
					.addGap(41)
					.addComponent(lblNewLabel_1, GroupLayout.PREFERRED_SIZE, 89, GroupLayout.PREFERRED_SIZE)
					.addPreferredGap(ComponentPlacement.RELATED)
					.addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
						.addGroup(gl_contentPane.createSequentialGroup()
							.addGap(40)
							.addComponent(lblNewLabel)
							.addPreferredGap(ComponentPlacement.RELATED, 46, Short.MAX_VALUE)
							.addComponent(lblNewLabel_2)
							.addGap(135))
						.addGroup(Alignment.TRAILING, gl_contentPane.createSequentialGroup()
							.addGap(35)
							.addComponent(text_userName, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
							.addGap(35)
							.addComponent(text_password, GroupLayout.PREFERRED_SIZE, 31, GroupLayout.PREFERRED_SIZE)
							.addGap(53)
							.addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING, false)
								.addComponent(btnNewButton_1, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
								.addComponent(btnNewButton, GroupLayout.DEFAULT_SIZE, 43, Short.MAX_VALUE))
							.addGap(40))))
		);
		contentPane.setLayout(gl_contentPane);
		//设置窗口剧中显示
		this.setLocationRelativeTo(null);
	}
	/**
	 * 登录按钮的方法
	 * @param e
	 */
	private void loginUserActionPerformed(ActionEvent evt) {

		String userName = text_name.getText();
		String password = new String(text_pass.getPassword());
		
		if(toolstring.isEmpty(userName)) {
			JOptionPane.showMessageDialog(null, "用户名不能为空");
			return;
		}
		if(toolstring.isEmpty(password)) {
			JOptionPane.showMessageDialog(null, "密码不能为空");
			return;
		}
		User user = new User(userName,password);
		Connection con = null;
		try {
			con = dbUtil.getCon();
			User currentUser = userDao.login( con, user);
			if(currentUser != null){
				dispose();
				new MainView().setVisible(true);
			}else{
				JOptionPane.showMessageDialog(null, "用户名或密码错误");
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			try {
				dbUtil.closeCon(con);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

本文地址：https://blog.csdn.net/weixin_46894841/article/details/107272369

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java空指针不知道错哪 急救！！！