CODEWITHSUNDEEP
javaarrays
hwilco
hwilco

Reputation: 7

Why is my array switching values?

I was trying to make a short code to switch the first and last values in an array and output a new array identical to the first array but with those values switched. After trying a few times, I realized my first (original) array kept switching its [0] value, and I can't tell why. This is the code.

import java.util.Arrays;
public class testing {
    public static void main(String[] args) {
       int[] original={1,2,3,4};
       int[] switched=original;
       switched[0]=original[original.length-1];
       switched[switched.length-1]=original[0];
       System.out.println(Arrays.toString(switched));

}

}

I wanted the output to be [4,2,3,1], but I always get [4,2,3,4].

Upvotes: 0

Views: 62

Answers (3)

libik
libik

Reputation: 23029

There is some magic you should know :).

In this line : int[] original={1,2,3,4}; you create array {1,2,3,4} and you store REFERENCE to it in your variable original

In this line : int[] switched=original; you copy the value of original which is REFERENCE to that array into the variable switched.

Now, you have two variables which are both referencing to the same array!

To create new array with same values, you can use this :

int [] switched = (int[])original.clone();

Upvotes: 0

Ghasan غسان
Ghasan غسان

Reputation: 5857

Because switched and original pointing to the same object.

Do:

import java.util.Arrays;
public class testing {
    public static void main(String[] args) {
        int[] original={1,2,3,4};
        int[] switched={1,2,3,4};
        switched[0]=original[original.length-1];
        switched[switched.length-1]=original[0];
       System.out.println(Arrays.toString(switched));
    }
}

Upvotes: 0

Jigar Joshi
Jigar Joshi

Reputation: 240870

both are reference to same array

initially

1,2,3,4

after

switched[0]=original[original.length-1];

4,2,3,4

after

switched[switched.length-1]=original[0];

4,2,3,4

Upvotes: 1

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