Why does FileInputStream.read() return int?

Question

1. Why does FileInputStream.read() method return type is int and not byte, clearly when it can read one byte at a time?

2. Because read() with array allows byte array and not int[] array.

Then why there is a difference here between 1st and 2nd methods?

Proof (why 1st method return type could have been byte):

-> I have a file where it had only one character (whose decimal = 157 and binary = 10011101)

-> When I read the first character using 1st method FileInputStream.read()
which returned me 157 
When type casted to byte, I got -99 which is now represented in 2's 
complement (Here decimal = -99 and binary = 10011101 again). 

Here, we are not losing any binary representation, then what's the real reason behind this?

Answer 1

1. Why does FileInputStream.read() method return type is int and not byte, clearly when it can read one byte at a time?

2. Because read() with array allows byte array and not int[] array.

Then why there is a difference here between 1st and 2nd methods?

Proof (why 1st method return type could have been byte):

-> I have a file where it had only one character (whose decimal = 157 and binary = 10011101)

-> When I read the first character using 1st method FileInputStream.read()
which returned me 157 
When type casted to byte, I got -99 which is now represented in 2's 
complement (Here decimal = -99 and binary = 10011101 again). 

Here, we are not losing any binary representation, then what's the real reason behind this?