正确调用方法：（Java）

Question

Create a method named getNextProjectIndex() that returns an int that gets the next index of the projects array that contains a -1.0. Find the next item in the projects array that contains a -1.0 and return that index of the array. This method should return -1 if the array is full. -1 is a common flag to indicate failure in methods that should only return non-negative integers.

I am having trouble calling this method in my main method. Does the problem lie in my getNextProjectIndex method or my main method in how I am calling it?

  public double getNextProjectIndex()
  {
    int i = 0;
    int full = -1;
    while(i < projects.length)
    {
      if (projects[i] == -1)
      {

        return i;
      }
      else if (i == (projects.length - 1) && projects[i] != -1)
      {
        return full;
      }

    }

    return i;

  }

Here is my main method:

public class Main {

  public static void main(String [ ] args)
  {
    Student testStudent = new Student("BL", "Hill", 34);
    int i = 0;
    System.out.println(testStudent.getFname() + " " + testStudent.getLname() );

    while(i < 5)
    {
      if(testStudent.getNextProjectIndex() != 0)
      {      
        testStudent.setProjectScore(10.0, i);
        System.out.println("Scores are: "+ testStudent.getProjectScore(i));
      }  


      i++;
    }


  }

}

When the program is run only one score is displayed rather than 5 scores. It does not completely run through the loop. Only -1 should be returned from that method if ALL slots in the array are filled.

Answer 1

Create a method named getNextProjectIndex() that returns an int

You have declared your method as returning a double, even though the spec says to return an int, and you are attempting to return an int i in the function:

public double getNextProjectIndex()
       ^^^^^^

Answer 2

I am guessing that your program hangs. In the while loop in getNextProjectIndex() , i is never incremented, thus causing an infinite loop.

--Edit-- Also, you have some cruft in the method try:

public int getNextProjectIndex()
{
  int i = 0;
  while(i < projects.length) {
    if (projects[i] == -1)
      return i;
    ++i;
  }
  return -1;
}

--Edit-- changed to while loop, since that's apparently required.

Answer 3

似乎您没有在getNextProjectIndex中增加while循环。