CHAPTER 10: Arrays

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10.6 Arrays Initializers

An array initializer may be specified in a declaration, creating an array and providing some initial values:

ArrayInitializer:

	{ VariableInitializersopt ,opt }

VariableInitializers:

	VariableInitializer

	VariableInitializers , VariableInitializer

The following is repeated from S8.3 to make the presentation here clearer:

VariableInitializer:

	Expression

	ArrayInitializer

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

The length of the constructed array will equal the number of expressions.

Each expression specifies a value for one array component. Each expression must be assignment-compatible (S5.2) with the array's component type, or a compile-time error results.

If the component type is itself an array type, then the expression specifying a component may itself be an array initializer; that is, array initializers may be nested.

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

As an example:

class Test {
	public static void main(String[] args) {
		int ia[][] = { {1, 2}, null };
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < 2; j++)
				System.out.println(ia[i][j]);
	}
}

prints:

1
2

before causing a NullPointerException in trying to index the second component of the array ia , which is a null reference.