Array declaration and initialization in Java. Arra

问题:

The following is the obvious and usual array declaration and initialization in Java.

int r[], s[];       //<-------
r=new int[10];
s=new int[10];

A very similar case behaves differently, when the position of [] is changed in the declaration statement like as shown below.

int []p, q[];       //<-------
p=new int[10];
q=new int[10][10];

Please look at the declaration. The position of [] has been changed from r[] to []p. In this case, the array q behaves like an array of arrays of type int (which is completely different from the previous case).

The question: Why is q, in this declaration int []p, q[]; treated as a two dimensional array?

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Additional information:

The following syntax looks wonky.

int []a[];

This however, complies fine and just behaves like int a[][]; or int [][]a;.

Hence, the following cases are all valid.

int [][]e[][][];
int [][][][][]f[][][][];

回答1:

Look at JLS on Arrays:

The [] may appear as part of the type at the beginning of the declaration, or as part of the declarator for a particular variable, or both.

and

Brackets are allowed in declarators as a nod to the tradition of C and C++. The general rules for variable declaration, however, permit brackets to appear on both the type and in declarators, so that the local variable declaration:

float[][] f[][], g[][][], h[];  // Yechh!

is equivalent to the series of declarations:

float[][][][] f;
float[][][][][] g;
float[][][] h;

So for example:

int []p, q[];

is just

int[] p, q[]

which is in fact

int p[]; int q[][]

The rest are all similar.

回答2:

The sane way of declaring a variable is

type name

So if type is int[], we should write

int[] array

Never write

int array[]

it is gibberish (though it's legal)