how to compare duplicated arrays

Question

Recently, I figured you can duplicate a array like this

System.arraycopy(src,0,dup,0,src.length);

However, even though the two arrays are the same, when you compare them using

if(src==dup)
   ...//print true
else if(src!=dup)
   ...//print false

It would always print false. Are there anyways to duplicate an array that does not change with the original one while also being able to compare those two correctly?

You are looking for "deep copy". There are a few questions that might be related. http://stackoverflow.com/questions/1564832/how-do-i-do-a-deep-copy-of-a-2d-array-in-java — , Jan 28 '17 at 04:37

score 1 · Accepted Answer · answered Jan 28 '17 at 02:25

Just as amahfouz stated in his answer, the references of two different arrays are compared (in the way you wrote in your post).

So, to be able to compare the elements, you should loop through them.

You can import Java.util.Arrays, and do this:

if(Arrays.equals(src, dup))
    System.out.println("Equal");
else
    System.out.println("Not Equal");

score 0 · Answer 2 · answered Jan 28 '17 at 02:18

0

The equality test just compares references, not content, so it will always return false for two different array references.

answered Jan 28 '17 at 02:18

amahfouz

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Do I use a for loop to compare src[x] to dup[x] then? – Spano Jan 28 '17 at 02:19

score 0 · Answer 3 · edited Jun 24 '17 at 01:37

0

You need to use

Arrays.equals()

edited Jun 24 '17 at 01:37

Pang

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answered Jan 29 '17 at 03:47

amahfouz

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how to compare duplicated arrays

3 Answers3