Suppressing sign-extension when upcasting or shifting in Java -

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i have feeling rather trivial question, i'm stumped. in application i'm keying things in lookup table pair of ints. thought easier concatenate 2 ints 1 long , use single long key instead. coming c background, hoping work:

int a, b; long l = (long)a << 32 | b;

my attempts replicate in java have frustrated me. in particular, because there no unsigned integral types, can't seem avoid automatic sign-extension of b (a gets left-shifted irrelevant). i've tried using b & 0x00000000ffffffff surprisingly has no effect. tried rather ugly (long)b << 32 >> 32, seemed optimized out compiler.

i hoping strictly using bit manipulation primitives, i'm starting wonder if need use sort of buffer object achieve this.

i use utility class with

public static long compose(int hi, int lo) {     return (((long) hi << 32) + unsigned(lo)); } public static long unsigned(int x) {     return x & 0xffffffffl; }  public static int high(long x) {     return (int) (x>>32); } public static int low(long x) {     return (int) x; }

for int x, y (negative or not) 

high(compose(x, y)) == x low(compose(x, y)) == y

holds , long z

compose(high(z), low(z)) == z

holds, too.


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