Array creation syntax in Java

Question

Here is the grammar for array creation in Java:

ArrayCreationExpression:
new PrimitiveType DimExprs [Dims]
new ClassOrInterfaceType DimExprs [Dims]
new PrimitiveType Dims ArrayInitializer
new ClassOrInterfaceType Dims ArrayInitializer

DimExprs:
DimExpr {DimExpr}

DimExpr:
{Annotation} [ Expression ]

Dims:
{Annotation} [ ] {{Annotation} [ ]}

Why here: new PrimitiveType DimExprs [Dims] Dims is in brackets? If it is in brackets then I can write this: new int [2][2] [[] []] where [2][2] is the DimExprs part and [] [] is the Dims part. What am I doing wrong here?

LearningMath · Accepted Answer · 2017-10-23 02:15:02Z

1

It seems that the answer was in front of my eyes but somehow i missed it. Here is the reason from the Java Specification:

The syntax [x] on the right-hand side of a production denotes zero or one occurrences of x. That is, x is an optional symbol. The alternative which contains the optional symbol actually defines two alternatives: one that omits the optional symbol and one that includes it.

This means you can write String[][][] s = new String[2][][];

Link: https://docs.oracle.com/javase/specs/jls/se8/html/jls-2.html#jls-2.4

answered Oct 23, 2017 at 2:15

LearningMath

8714 gold badges18 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Array creation syntax in Java

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related