The unary minus operator (-) is used in the form
-operand
The unary minus operator negates the value of its operand.
The operand must be a primitive numeric type.
If the type of the operand is byte, short, or char, it promotes the operand to the int type.
The following example illustrates its use:
byte b1 = 10; byte b2 = -5; b1 = b2; // Ok. byte to byte assignment
In the following code, b2 is of the type byte. unary minus operator - on b2 promotes its type to int. -b2 is of type int. int to byte assignment is not allowed.
byte b1 = 10; byte b2 = -5; b1 = -b2; // A compile-time error.
To fix the error, add casting.
b1 = (byte) -b2; // Ok