Java shl and shr filling problem

Is there a way to shift left or right without the byte loss, so that the bytes filled are the ones that are beeing taken?

e.g.:10010 shr 2 => 10100 or: 11001 shl 4 => 11100

the loss of info开发者_运维技巧rmation seems quite inconvenient, since you're not supposed to use it for math anyway..

i just want to send packages over the network in different byte order, so shifting back is important to me

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What you're trying to do is bitwise rotation which is supported in Java.

public class Binary {

    public static void main(String[] args) {
        Integer i = 18;

        System.out.println(Integer.toBinaryString(i));
        i = Integer.rotateRight(i, 2);

        System.out.println(Integer.toBinaryString(i));
    }

}

This will print out:

10010
10000000000000000000000000000100

The 2 bits which were shifted off have been rotated round to the start. However there is a lot of 0 padding in the middle because an integer in Java takes up 32 bits.

If you wanted to implement this behaviour yourself, internally it is implemented as:

public static int rotateLeft(int i, int distance) {
    return (i << distance) | (i >>> -distance);
}

And:

public static int rotateRight(int i, int distance) {
    return (i >>> distance) | (i << -distance);
}