对象被视为未初始化的变量

Question

I have a Student class and my main program, I create a new student object like so:

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

However when I later try to access the printArrays method in the student class like so:

newStudent.printArrays();

I get a error saying with newStudent saying:

java: variable newStudent might not have been initialized

But Student.printArrays(); works fine.

Is this problem due to the object not being created until run time? How can I fix this error?

EDIT:

Where Student is called:

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;

Student 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

You probably have something similiar to this in your code:

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

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

It does not have to be an if block, could also be any other block like a try/catch. To fix it, change Student newStudent; to Student newStudent = null; .