public class Test1{ public static void main(String[ ]args){ ma(); public void ma( )throws SQLException{ throw new SQLException();}}

这段Java代码中有一个错误，需要在ma()方法前添加关键字“static”才能使Test1类中的main()方法调用ma()方法。此外，ma()方法中抛出了SQLException异常，需要在方法名后添加“throws SQLException”来声明该异常。修改后的代码如下所示：

public class Test1 {
public static void main(String[] args) throws SQLException {
ma();
}

public static void ma() throws SQLException {
throw new SQLException();
}
}

相关问题

package com.util; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.Random; import com.util.SQLConn; public class RandomStringGenerator { private static final String INSERT_SQL = "INSERT INTO strings (value) VALUES (?)"; private static final int STRING_LENGTH = 10; public RandomStringGenerator() throws SQLException { try {Connection conn = SQLConn.openDB(); PreparedStatement pstmt = conn.prepareStatement(INSERT_SQL); { // 生成随机字符串 Random rand = new Random(); StringBuilder sb = new StringBuilder(); for (int i = 0; i < STRING_LENGTH; i++) { char c = (char) (rand.nextInt(26) + 'a'); sb.append(c); } String str = sb.toString(); // 保存到数据库 pstmt.setString(1, str); pstmt.executeUpdate(); System.out.println("随机字符串已保存到数据库中：" + str); }} catch (SQLException e) { // exception handling here throw e; } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String[] args) { try { RandomStringGenerator generator = new RandomStringGenerator(); } catch (SQLException e) { // exception handling here e.printStackTrace(); } } }优化代码

以下是对代码的优化建议：

1. 使用 try-with-resources 语句，可以自动关闭连接和 PreparedStatement，避免资源泄漏。

2. 将 INSERT_SQL 和 STRING_LENGTH 定义为常量，可以提高代码的可读性。

3. 将 SQLConn.openDB() 方法改为静态方法，可以在不创建对象的情况下直接调用。

4. 在异常处理中，可以将异常信息记录在日志中，方便后续排查问题。

下面是优化后的代码：

package com.util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Random;

public class RandomStringGenerator {
    private static final String INSERT_SQL = "INSERT INTO strings (value) VALUES (?)";
    private static final int STRING_LENGTH = 10;

    public RandomStringGenerator() {
        try (Connection conn = SQLConn.openDB();
             PreparedStatement pstmt = conn.prepareStatement(INSERT_SQL)) {
            // 生成随机字符串
            Random rand = new Random();
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < STRING_LENGTH; i++) {
                char c = (char) (rand.nextInt(26) + 'a');
                sb.append(c);
            }
            String str = sb.toString();

            // 保存到数据库
            pstmt.setString(1, str);
            pstmt.executeUpdate();
            System.out.println("随机字符串已保存到数据库中：" + str);
        } catch (SQLException e) {
            // 记录异常信息
            System.err.println("保存随机字符串到数据库时出现异常：" + e.getMessage());
        } catch (ClassNotFoundException e) {
            // 记录异常信息
            System.err.println("无法找到数据库驱动程序：" + e.getMessage());
        }
    }

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

import javax.swing.; import java.awt.; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.sql.*; public class demo { public static void main(String[] args) throws RuntimeException { JFrame jFrame=new JFrame("登录窗口"); JLabel oo=new JLabel("账号",JLabel.CENTER); JLabel qq=new JLabel("密码",JLabel.CENTER); JTextField ii = new JTextField(10); JPasswordField kk = new JPasswordField(10); JButton mm=new JButton("确定"); JButton ss=new JButton("注册"); JPanel p=new JPanel(); p.setLayout(new GridLayout(3,2)); JPanel p1=new JPanel(); p1.add(oo); p1.add(ii); JPanel p2=new JPanel(); p2.add(qq); p2.add(kk); JPanel p3=new JPanel(); p3.add(mm); p3.add(ss); p.add(p1); p.add(p2); p.add(p3); jFrame.setSize(400,300); jFrame.setDefaultCloseOperation(jFrame.EXIT_ON_CLOSE); jFrame.setVisible(true); jFrame.add(p); ss.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { demo d=new demo(); d.pp(p1,p2); } }); } public void pp(JPanel i, JPanel name){ try{ Class.forName("com.mysql.cj.jdbc.Driver"); Connection configuration= DriverManager.getConnection("jdbc:mysql://localhost:3306/xscj?db_student","root","123456"); Statement system=configuration.createStatement(); String sql=("insert into opop values("+i +","+"'"+name+"')"); system.executeUpdate(sql); String ll="select * from opop"; ResultSet set=system.executeQuery(ll); while(set.next()){ String id =set.getString("ID"); String pp=set.getString("name"); System.out.println(id+pp); } System.out.println(" "); } catch (ClassNotFoundException e) { throw new RuntimeException(e); } catch (SQLException e) { throw new RuntimeException(e); } } public void uu(){ } }优化这段代码

以下是对代码进行优化的建议：

1. 将`demo`这个类重命名为更具描述性的类名，比如`LoginWindow`。

2. 将所有的Swing组件创建和UI布局放在一个独立的方法里，如`createUI()`，然后在主方法中调用该方法。这样可以提高代码的可读性和可维护性。

3. 避免在主线程中进行数据库操作。应该将数据库操作放在单独的线程中，以免阻塞UI线程，导致用户体验不佳。

4. 将数据库操作封装在独立的类中，比如`DatabaseHelper`，以提高代码的可重用性和可维护性。

5. 在处理异常时，应该将异常抛出或记录到日志中，而不是简单地抛出`RuntimeException`。

下面是优化后的代码示例：

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

public class LoginWindow {
    private JTextField accountTextField;
    private JPasswordField passwordField;

    public static void main(String[] args) {
        LoginWindow loginWindow = new LoginWindow();
        loginWindow.createUI();
    }

    private void createUI() {
        JFrame jFrame = new JFrame("登录窗口");
        JLabel accountLabel = new JLabel("账号", JLabel.CENTER);
        JLabel passwordLabel = new JLabel("密码", JLabel.CENTER);
        accountTextField = new JTextField(10);
        passwordField = new JPasswordField(10);
        JButton loginButton = new JButton("确定");
        JButton registerButton = new JButton("注册");

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(3, 2));
        JPanel panel1 = new JPanel();
        panel1.add(accountLabel);
        panel1.add(accountTextField);
        JPanel panel2 = new JPanel();
        panel2.add(passwordLabel);
        panel2.add(passwordField);
        JPanel panel3 = new JPanel();
        panel3.add(loginButton);
        panel3.add(registerButton);
        panel.add(panel1);
        panel.add(panel2);
        panel.add(panel3);

        jFrame.setSize(400, 300);
        jFrame.setDefaultCloseOperation(jFrame.EXIT_ON_CLOSE);
        jFrame.setVisible(true);
        jFrame.add(panel);

        registerButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String account = accountTextField.getText();
                String password = new String(passwordField.getPassword());
                DatabaseHelper.addUser(account, password);
            }
        });
    }
}

class DatabaseHelper {
    private static final String DATABASE_URL = "jdbc:mysql://localhost:3306/xscj?db_student";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "123456";

    public static void addUser(String account, String password) {
        new Thread(() -> {
            try (Connection connection = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);
                 Statement statement = connection.createStatement()) {
                String sql = "INSERT INTO opop VALUES ('" + account + "', '" + password + "')";
                statement.executeUpdate(sql);

                String query = "SELECT * FROM opop";
                ResultSet resultSet = statement.executeQuery(query);
                while (resultSet.next()) {
                    String id = resultSet.getString("ID");
                    String name = resultSet.getString("name");
                    System.out.println(id + name);
                }
                System.out.println(" ");
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }).start();
    }
}

希望这些优化可以对您有所帮助。