Question

几个月前，我开始研究Java，现在我陷入了异常处理的困境，每一个 StudentId，TeamID 都必须进行一轮异常检查，以便用户输入字母代替整数，它应该发送回同一位置再次询问该值。我正在使用ArrayList来存储数据。同样，所有 get **********（）方法都在另一个名为 Student 的类中。 studentList 是我的变量，用于访问我的 ArrayList

请通过修复它来帮助我找到错误的出处，以便使我的概念更加清楚。我被困在这里

/***
 * A method to check if the same Student ID exists in the ArrayList previously
 * @param StudentId
 * @return
 */

public static boolean checkStudent(int StudentId) {

    for (Student stud : studentList) {
        if(stud.getStudentId() == StudentId) {
            return true;
        }
    }
    return false;
}

/***
 * Method to add student in the ArrayList
 * @param scn
 */

public static void addStudent(Scanner scn) {

    System.out.println("Enter student ID");
    int studentId;
    studentId = scn.nextInt();
    **//enter the try catch statement here 
    //ask the user to write the integer not string and revert to this scanner variable**
    if (checkStudent(studentId)) {

        System.out.println("Student Id " + studentId + " already exists,Please enter the valid details ");

        addStudent(scn);


        //break;
   }else{
       System.out.println("Enter student name:");
       String studentName;
       studentName = scn.next();
       System.out.println("Enter team ID:");

        **try{
        int teamId;
       teamId = scn.nextInt();
        //ask the user to write the integer not string and revert to this scanner variable
       }catch(NumberFormatException e){
           //
       }finally{
        //do something    
        }**

        System.out.println("Enter team name:");
       String teamName;try{
       teamName = scn.next();    
       }


       Student std = new Student(studentId, studentName, teamId, teamName);
       studentList.add(std);

       System.out.println("*******************************************");
       System.out.println("student with Student ID" + studentId +" added succesfully");
       System.out.println("*******************************************");   
   }
}

Answer 1

我将使用while循环为您提供另一个提示，您可以根据需要进一步实现此逻辑。您可以在致电checkStudent()

之前使用它

System.out.println("Enter student ID");
while (true) {
    try {
        int studId= scn.nextInt();
        // terminate loop if everything is ok  
        break;
    } catch (NumberFormatException e) {
        // on an exception, loop still continues
    }
}

Answer 2

请阅读try..catch statement in the Java language specification或任何教程（您可以通过在您喜欢的搜索引擎中键入“ java try catch”来找到许多内容）。

我确定你能弄清楚。

在Java中使用ArrayList进行异常处理

2 个答案: