java - 对象被视为未初始化的变量

Question

我有一个 Student 类和我的主程序，我创建一个新的学生对象，如下所示:

学生 newStudent = new Student(newStudentName, newMarkOne, newMarkTwo, newMarkThree);

但是，当我稍后尝试访问学生类中的 printArrays 方法时，如下所示:

newStudent.printArrays();

我收到一条错误消息，newStudent 说:

java:变量 newStudent 可能尚未初始化

但是 Student.printArrays(); 工作正常。

此问题是否是由于直到运行时才创建对象造成的？我该如何修复这个错误？

编辑:

Student 的调用位置:

case 1:
  System.out.println("Enter the student's name in this format - Surname,Forename: ");
  newStudentName = input.next();
  while (!newStudentName.matches("[A-Z][a-zA-Z]*,[A-Z][a-zA-Z]*")) {
    System.out.println("Enter name in correct format - Surname,Forename (no whitespace and uppercase first letters)");
    newStudentName = input.next();
  }
  System.out.println("Enter the first mark: ");
  newMarkOne = input.nextInt();
  System.out.println("Enter the second mark: ");
  newMarkTwo = input.nextInt();
  System.out.println("Enter the third mark: ");
  newMarkThree = input.nextInt();
  Student newStudent = new Student(newStudentName, newMarkOne, newMarkTwo, newMarkThree);
break;
case 2:
  System.out.println("Which student would you like to delete?");
  newStudent.printArrays();
break;

学生类(class):

public class Student {
  private String studentName;
  private int markOne, markTwo, markThree;
  private double score;
  private static String course = "French";
  private static String[] studentNamesArray = new String[10];
  private static int[][] studentMarksArray = new int[10][3];
  private static int nameArrayCount, markArrayCount;

  public Student(String newStudentName, int newMarkOne, int newMarkTwo, int newMarkThree) {
    if (nameArrayCount < 10) {
      this.studentName = newStudentName;
      this.markOne = newMarkOne;
      this.markTwo = newMarkTwo;
      this.markThree = newMarkThree;
      this.score = ((markOne + markTwo + markThree) / 3);
      studentNamesArray[nameArrayCount] = studentName;
      nameArrayCount = nameArrayCount + 1;
      studentMarksArray[markArrayCount][0] = markOne;
      studentMarksArray[markArrayCount][1] = markTwo;
      studentMarksArray[markArrayCount][2] = markThree;
      markArrayCount = markArrayCount + 1;
    }
    else if (nameArrayCount == 10) {
      System.out.println("******Array is full, please delete a student before adding another.*****");
    }
  }
}

Answer 1

您的代码中可能有类似的内容:

Student newStudent;
if (condition) {
   newStudent = new Student(newStudentName, newMarkOne, newMarkTwo, newMarkThree);
}

newStudent.printArrays(); // here you get the "might not have been initialized"

它不一定是 if block ，也可以是任何其他 block ，例如 try/catch。要修复此问题，请将 Student newStudent; 更改为 Student newStudent = null;。