Pass by Reference in Java

Pass by reference in Java is a method of passing parameters to a method. When a parameter is passed by reference, the method receives a reference to the original object, not a copy of the object. This means that any changes made to the object within the method will be reflected in the original object.

Pass by reference in Java example

Following is an example of pass by reference in Java:

import java.util.*;
public class PassByReference {

    public static void main(String[] args) {
        int[] numbers = new int[]{10, 20, 30};
        System.out.println("The original numbers array is: " + Arrays.toString(numbers));
        changeNumbers(numbers);
        System.out.println("The modified numbers array is: " + Arrays.toString(numbers));
    }

    public static void changeNumbers(int[] numbers) {
        numbers[0] = 100;
        numbers[1] = 200;
        numbers[2] = 300;
    }
}

In this example, the array numbers is passed by reference to the method changeNumbers(). This means that the method does not receive a copy of the array, but rather a reference to the original array. Any changes made to the array within the method will be reflected in the original array.

The output of the program is:

The original numbers array is: [10, 20, 30]
The modified numbers array is: [100, 200, 300]

As we can see, the array numbers is modified by the call to the changeNumbers() method. This is because numbers was passed by reference to the method, and the method was able to modify the original array.

When to use pass by reference

Pass by reference should be used in Java when:

• We want changes to the parameter to be reflected in the calling method.
• We need to access the original object reference.

When not to use pass by reference

Pass by reference should not be used in Java when:

• We do not want changes to the parameter to be reflected in the calling method.
• We want to avoid the overhead of passing a reference.

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