15.9.2

Example: Array Creation Evaluation Order

EXPRESSIONS

15.9.2   Example: Array Creation Evaluation Order

In an array creation expression ( 15.9), there may be one or more dimension

expressions, each within brackets. Each dimension expression is fully evaluated

before any part of any dimension expression to its right.

Thus:

class Test {

public static void main(String[] args) {

int i = 4;

int ia[][] = new int[i][i=3];

System.out.println(

"[" + ia.length + "," + ia[0].length + "]");

}

}

prints:

[4,3]

because the first dimension is calculated as

4

 before the second dimension expres 

sion sets

i

 to

3

.

If evaluation of a dimension expression completes abruptly, no part of any

dimension expression to its right will appear to have been evaluated. Thus, the

example:

class Test {

public static void main(String[] args) {

int[][] a = { { 00, 01 }, { 10, 11 } };

int i = 99;

try {

a[val()][i = 1]++;

} catch (Exception e) {

System.out.println(e + ", i=" + i);

}

}

static int val() throws Exception {

throw new Exception("unimplemented");

}

}

prints:

java.lang.Exception: unimplemented, i=99

because the embedded assignment that sets

i

 to

1

 is never executed.

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