question about long

[xu han]

int n1=0xffffffff;
println(Integer.toBinaryString(n1));

As i try to add a f behind 0xffffffff,the compiler response a error,int is out of range.
right,because int has 32 bits. the output is right .
11111111111111111111111111111111

long n2=0xffffffff;
println(Long.toBinaryString(n2));

as i try to add a f behind 0xffffffff,the compiler response a error too,int is out of range.
why does compiler look 0xfffffff as a int?
the output is 1111111111111111111111111111111111111111111111111111111111111111.
since 0xffffffff has 32bits,why the output has 64bits "1"?

long n2=0xffffffffffffffffl;

the output is right 1111111111111111111111111111111111111111111111111111111111111111.
thanks a lot!

[Tony Docherty]

Hard coded integer type values are considered by the compiler to be ints unless you tell it otherwise. If you add an 'L' to the right hand end the compiler will consider it to be a long ie:

long n2=0xfffffffffffL;
println(Long.toBinaryString(n2)); 

[xu han]

Thanks for your help!
Hard coded integer type values are considered by the compiler to be ints unless you tell it otherwise.

int n1=0xffffffff;
println(Integer.toBinaryString(n1));
long n2=0xffffffff;
println(Long.toBinaryString(n2));

output:
11111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
why the second is
1111111111111111111111111111111111111111111111111111111111111111
not
11111111111111111111111111111111
the hexadecimal value are equal,but the output are not equal. why?

[Campbell Ritchie]

You are not assigning a long to the second number. You are assigning an int. Remember all integer literals are unsigned, so you can write 0xffff_ffff as if it were a positive number, but it represents -1.
Now you are assigning the int value -1 to your long; it undergoes widening conversion to -1L. And -1L is sixty‑four 1 bits.
If you want to keep it as thirty‑two 1 bits, you would have to write 0xffff_ffffL. You can only use the _ character in Java7.

[xu han]

I see。
thanks Campbell Ritchie and Tony Docherty。