Empty arrays automatically initialize contents?

Question

How come

int alone;
System.out.println(alone);

Gives errors but

 int[] arr = new int[1];
 System.out.println(arr[0]);
         


        

Answer 1

From the language standard

Otherwise, a one-dimensional array is created of the specified length, and each component of the array is initialized to its default value (§4.12.5).

And the default values are:

• For type byte, the default value is zero, that is, the value of (byte)0.

• For type short, the default value is zero, that is, the value of (short)0.

• For type int, the default value is zero, that is, 0.

• For type long, the default value is zero, that is, 0L.

• For type float, the default value is positive zero, that is, 0.0f.

• For type double, the default value is positive zero, that is, 0.0d.

• For type char, the default value is the null character, that is, '\u0000'.

• For type boolean, the default value is false.

• For all reference types (§4.3), the default value is null.