When you treat a variable of one type to another type, it is called type casting. Up casting supports automatic conversion but in case of low casting you need to explicitly specify it.
Java Code: Type Casting
byte -> short -> int -> long -> float -> double
int i = 5;
long j = i; //Right. Up casting or implicit casting
byte b1 = i; //Wrong. Compile time error “Type Mismatch”.
byte b2 = (byte) i ; //Right. Down casting or explicit casting is required.