else if (e.getSource().equals(login)) { String id=jt1.getText(); String username = jt2.getText(); String password = String.valueOf(jpf.getPassword()); // 遍历所有学生信息，判断输入的用户名和密码是否匹配 boolean isMatched = false; for (Student student : students) { if (username.equals(student.getUserName()) && password.equals(String.valueOf(student.getPassword()))&&id.equals(student.getId())) { isMatched = true; break; } }修改代码

在对所有学生信息进行遍历之前，您可以先进行一些输入验证，比如判断输入框是否为空。另外，您可以把判断逻辑封装成一个方法，以提高代码可读性和复用性。修改后的代码如下所示：

else if (e.getSource().equals(login)) {
    String id = jt1.getText();
    String username = jt2.getText();
    String password = String.valueOf(jpf.getPassword());

    // 输入验证
    if (id.isEmpty() || username.isEmpty() || password.isEmpty()) {
        JOptionPane.showMessageDialog(this, "请输入完整信息！", "提示", JOptionPane.WARNING_MESSAGE);
        return;
    }

    // 判断用户名、密码和ID是否匹配
    boolean isMatched = isStudentMatched(id, username, password);
    if (isMatched) {
        JOptionPane.showMessageDialog(this, "登录成功！", "提示", JOptionPane.INFORMATION_MESSAGE);
    } else {
        JOptionPane.showMessageDialog(this, "用户名、密码或ID错误！", "提示", JOptionPane.WARNING_MESSAGE);
    }
}

// 判断学生信息是否匹配
private boolean isStudentMatched(String id, String username, String password) {
    for (Student student : students) {
        if (id.equals(student.getId()) && username.equals(student.getUserName()) && password.equals(String.valueOf(student.getPassword()))) {
            return true;
        }
    }
    return false;
}