How to check a 2D matrix is empty?

Question

I think that all we need is

if (matrix.length == 0)

However, I saw some of them write

if (matrix == null || matrix.length == 0 || matrix[0].length == 0)

Is my version enough to check a matrix is empty or not or we need to write the above version?

Try testing your version with actual different values for `matrix`. You'll find out why quickly. — markspace, Mar 13 '16 at 20:47

Vucko · Accepted Answer · 2016-03-13T21:45:46.113

6

You will get a NullPointerException if you call matrix.length() if matrix is null, that's why the second check is better.

edited Mar 13 '16 at 21:45

answered Mar 13 '16 at 20:55

Vucko

Can we just write if(matrix==null)and leave out the rest of two condition? @Vucko – KKKK Mar 13 '16 at 20:58
no, because matrix can be not null and still empty if it has no data in it. – Vucko Mar 13 '16 at 21:45

1 Answers1