Sort 2d arrays Using Arrays.sort in java

Question

Can anyone tell what is the difference between these lines?

Arrays.sort(pairs, (a, b) -> a[0] - b[0])
Arrays.sort(pairs, (a, b) -> a[1] - b[1]);

First line will not compile because of lack of ; at the end. But if we add that ; it will try to sort arrays based on values of their first column (accessed via [0]). Second will try to sort based on values of second column (accessed via [1]). — Pshemo
– Pshemo, Commented Aug 15, 2021 at 8:44
Also, comparing the values using subtraction may fail if an integer overflow/underflow occurs, so it's better to use Integer::compare — Nowhere Man
– Nowhere Man, Commented Aug 15, 2021 at 12:37

Joshua Fox · Accepted Answer · 2021-08-15 08:43:46Z

1

The first sorts based on the first element of the arrays that are being sorted, and the other sorts based on the next element.

If the input was:

[2, 33], [4, 22], [3, 11]

The first would produce

[2, 33], [3, 11], [4, 22]

and the second would produce

[3, 11], [4, 22], [2, 33]

answered Aug 15, 2021 at 8:43

Joshua Fox

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Comments

Zubair Ahmed · Accepted Answer · 2021-08-15 08:58:47Z

0

According to your code. It looks that the first line will not execute. Because it is missing the terminator.

Arrays.sort(pairs, (a, b) -> a[0] - b[0]);

And the second line will run and it gives the output according to your input.

Arrays.sort(pairs, (a, b) -> a[1] - b[1]);

answered Aug 15, 2021 at 8:58

Zubair Ahmed

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