byte expressions in java

[mayurapink]

byte b1=10;
byte b2=20;
byte b3=b1+b2;

The above code causes Compile time error.

I understand byte,short and char is treated as int in an expression.

So, i changed the code as:

byte b1=10;
byte b2=20;
byte b3=(byte)(b1+b2);

(or)

byte b1=10;
byte b2=20;
int b3=b1+b2;

Please help me to understand why should it treated as int?

Can it perform addition on byte types itself?

[r035198x]

byte b1=10;
byte b2=20;
byte b3=b1+b2;

The above code causes Compile time error.

I understand byte,short and char is treated as int in an expression.

So, i changed the code as:

byte b1=10;
byte b2=20;
byte b3=(byte)(b1+b2);

(or)

byte b1=10;
byte b2=20;
int b3=b1+b2;

Please help me to understand why should it treated as int?

Can it perform addition on byte types itself?

Arithmetic operators - *, /, %, +, - can be applied to numeric types only (at least int) except + which can also be applied to String literals.

See post #2 of the Free classes thread

[JosAH]

Please help me to understand why should it treated as int?

Can it perform addition on byte types itself?

Nope, just for simplicity reasons; the (virtual) cpu of the (virtual) machine has int
registers only (discaring the floating point processor). Every calculation not
involving floating point or long values implicitly casts every operand to an int
before performing any calculation at all.

The compiler can only detect so much. so: 'byte b1= 10' is fine, but the compiler
can't deduce that 'byte b2= b1+10' is fine as well because it 'thinks' that b1 can
be promoted to an int and maybe the int value doesn't fit in a byte. You should
always cast in such situations.

kind regards,

Jos

[prometheuzz]

...
but the compiler can't deduce that 'byte b2= b1+10' is fine as well because
it 'thinks' that b1 can be promoted to an int and maybe the int value doesn't
fit in a byte. You should always cast in such situations.

Just a small addition: or declare b1 as final: that way the compiler is reassured that everything will fit in a single byte.

Compile error:

byte b1 = 10;
byte b2 = b1+5;

No errors:

final byte b1 = 10;
byte b2 = b1+5;