java - Why does ByteArrayOutputStream use int?

Question

Maybe someone can help me understand because I feel I'm missing something that will likely have an effect on how my program runs.

I'm using a ByteArrayOutputStream. Unless I've missed something huge, the point of this class is to create a byte[] array for some other use.

However, the "plain" write function on BAOS takes an int not a byte (ByteArrayOutputStream.write).

According to this(Primitive Data Types) page, in Java, an int is a 32-bit data type and a byte is an 8-bit data type.

If I write this code...

int i = 32;
byte b = i;

I get a warning about possible lossy conversions requiring a change to this...

int i = 32;
byte b = (byte)i;

I'm really confused about write(int)...

Answer 1

In order to facilitate unsigned bytes above 0x7F this takes place. The int will be silently narrowed to be written. In fact, the code does that with a (byte) cast.

As Ingo states:

A possible reason could be that the byte to write will most often be the result of some operation that automatically converts its operands to int[, like] some bit operations. Hence, the code would be littered with casts to byte, that add nothing to understanding.