Question

我正在尝试打印列表的内容，但是我得到了错误的值。

（com.school.student.StudentModel@949774e）代替查询结果

下面是bean

public class StudentModel {
    int studentId;
    String studentName; 

    public int getStudentId() {
        return studentId;
    }

    public void setStudentId(int restaurantId) {
        this.studentId = resturantId;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }
}

查询方法：

public static List<StudentModel> StudentDetails() {
    Connection conn = connection.dbConnection();
    List<StudentModel> students = new ArrayList<StudentModel>();

    try {

        String checkCst = "select * from student";

        PreparedStatement stmt = conn.prepareStatement(checkCst);

        ResultSet rCST = stmt.executeQuery();

        while (rCST.next()) {
            StudentModel  rM = new StudentModel ();
            rM.setStudentId(rCST.getInt(1));
            rM.setStudentName(rCST.getString(2));
            students.add(rM);
        }

    } catch (Exception ex) {
        ex.printStackTrace();
    }

    return students;
}

这就是我试图调用方法的方法：

StudentModel rM = new StudentModel();
List<StudentModel> student = ListStudentDetails.StudentDetails();

for (int i = 0; i < student.size(); i++) {
    System.out.println(" " + student.get(i));
    System.out.println(" " + student.get(i));
}

查询工作正常，所以我假设在调用StudentDetails方法时for循环中出现问题。

非常感谢。

Answer 1

你的if子句有问题，应该是一段时间。

                while (rCST.next()) {
                    StudentModel  rM = new StudentModel ();
                    rM.setStudentId(rCST.getInt(1));
                    rM.setStudentName(rCST.getString(2));
                    students.add(rM);
                }

您可以尝试打印对象的参考值，例如学生的姓名

System.out.println(" " + student.get(i).getStudentName());

或者你可以

public class StudentModel {

    int studentId;
    String studentName; 

    public int getStudentId() {
        return studentId;
    }

    public void setStudentId(int restaurantId) {
        this.studentId = resturantId;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    @Override
    public String toString(){
       return this.studentName;
    }

}

循环使用List Java

1 个答案: