In place works for int[] but not for int in java

Question

The value of int a remains same after calling function (testInPlaceInteger(a)) but for int[] arr changes after calling the function (squareArrayInPlace). Why is int a value not changing?
Following is my code:

public class Test {
  public static void main(String[] args) {
    int a = 5;
    int[] arr = new int[] {3, 4};

    Test test = new Test();

    test.testInPlaceInteger(a);
    test.squareArrayInPlace(arr);

    System.out.println(a);

    for (int i : arr) {
      System.out.println(i);
    }
  }

  public void testInPlaceInteger(int num) {
    num *= num;
  }

  public void squareArrayInPlace(int[] intArray) {
    for (int i = 0; i < intArray.length; i++) {
      intArray[i] *= intArray[i];
    }
  }
}

Output:

5
9
16

@StephenC yeah , but just to keep thing simple, object can maintain it's states and behavior throughout function calls whereas primitive can't :) — Pavneet_Singh, Dec 29 '16 at 10:44
I know that. But when you write that primitives are passed by value, some people would think that you are implying that reference types are not passed by value. — Stephen C, Dec 29 '16 at 11:36

score 0 · Answer 1 · answered Dec 29 '16 at 06:48

0

Because int is a primitive type and is passed by value. However, intArray[i] is a memory location, so you can change the value within.

answered Dec 29 '16 at 06:48

Héctor

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In place works for int[] but not for int in java

1 Answers1