0 itself has no type, and the type depends on what variable it is assigned to.

For example, int I = 0；; Then 0 is an integer, if long I = 0；; 0 is a long type.

The number types are: byte short int long char, which are represented by 8, 16, 32, 64, 16 respectively. In some places, char may not be included in the category of integer, but in essence char type is a subset of int.