Java Language Specification is the right place to look for such information:
Array components are unnamed variables that are created and initialized to default values (ยง4.12.5) whenever a new object that is an array is created
Default values themselves are given in section 4.12.5.
- 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, the default value is null.