Assignining one array to other which are diffrent in size in java

Question

Given code:

float []    f3 = {2.7f};
float [] [] f2 = {{42.0f}, {1.7f, 1.9f}};

What should I understand by statement if(f2[1]==f3)? The result is false, but are we comparing their sizes?

`==` is referential equality. `a == b` is true only if `a` and `b` are *the same reference*. It doesn't matter how big they are or what's in them. — Chris Martin, Apr 09 '14 at 07:19

score 1 · Answer 1 · edited May 23 '17 at 10:33

1

You are comparing references, because in Java arrays are objects: Since these are different objects, you will get false.

If you had this:

int[] f3 = { 100 };
int[][] f2 = { f3, { 2, 1 } };

System.out.println(f2[0] == f3);

The output would be true because you are adding the reference f3 as an element of the array f2.

edited May 23 '17 at 10:33

Community

answered Apr 09 '14 at 07:19

Christian Tapia

score 0 · Answer 2 · edited Apr 09 '14 at 07:19

0

f2[1] == f3 compares references to different float[] instances and it will never return true. Use Arrays.equals instead

edited Apr 09 '14 at 07:19

ifloop

answered Apr 09 '14 at 07:18

Evgeniy Dorofeev

score 0 · Answer 3 · edited Apr 09 '14 at 07:48

0

f2[1]==f3 tests if f2[1] points to the same address as f3. Thus even if you write

float [] f3={1.7f,1.9f};
float [] [] f2={{42.0f},{1.7f,1.9f}};

it will still come back false. Only if you assign

f2[1] = f3;

or vice versa f2[1]==f3 will be true.

edited Apr 09 '14 at 07:48

Adaephon

answered Apr 09 '14 at 07:24

snOOfy

3 Answers3