Question

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Arrays with trailing commas inside an array initializer in Java

Why the following statement is correct in java:

int[][] a = { {1,2,}, {3,4}};

Whether should be compilation error because of unnecessary comma ?

Answer 1

Trailing comma in a array initialization like that are ignored by compiler. Those are generally added so that later on adding something to the array, just requires adding the element without worrying about comma.

It is wierd, but is allowed.

This is also listed in JLS - Section#10.6 (Array Initializers): –

An array initializer is written as a comma-separated list of
expressions, enclosed by braces { and }.

A trailing comma may appear after the last expression in an array
initializer and is ignored.