Question

In the following code the method array1 won’t return the avarage because its return type is void.

I know what void means but can someone explain to me what is a void result type and how to make this method return the avarage:

public class JavaApplication4 {
    public static void main(String[] args) {
    int[] a = {1,2,3,4};

    double result = array1 (a);
}

public static array1 (int[] b) {
    double avarage;
    int total = 0;
    for (int x:b) {
        total += x;
    }

avarage = total / b.length;
return avarage;
}

Answer 1

A return type of void means that a method doesn’t return anything. This is useful when you want to preform an operation on an array, but there isn’t any value associated with the operation. For example, say that you wanted to swap the first and last element in an array, you could write some method like this (ignore the necessary error checking)

 public void swapArrayLocs(int[] swapping){
      int temp = swapping[0];
      swapping[0] = swapping[swapping.length - 1];
      swapping[swapping.length - 1] = temp;
 }

When you call this method, you’re not expecting any sort of result from it, you’re expecting your program to just take care of business and continue executing.

In this case, you actually want your array1(int[]) method to make its available to the rest of the program. You do this by specifying the return type of the function, which tells the rest of the program what type of information you expect that function to return. In your case, you’d do this by changing your method declaration to.

public static double array1(int[] b){
    //the same method body
}

Note how in this case the word double is inserted after static. This tells the calling function that when it executes array1, the method will give back a value of type double. Contrast this with what you had before which said that the method would not give back any type of information.