What are some alternatives to multiplication in Java?

Question

To be more specific, there are constraints on my assignment that disallow me to use multiplication and more than 2 if-else statements. The method should take a number, such as 0xAAA5, and replace one of the 4-bit sections with the given nibble, such as 0x1. Here is my code right now:

public static int setNibble(int num, int nibble, int which) {
    num = num & (0xFFFF - (0xF << (4 * which)));
    num = num | ( (nibble) << (4 * which) );

    return num;
}

I basically just want to left shift by which*4, but I can't figure out how to do that without multiplication, or some kind of if-else statement.

score 2 · Accepted Answer · answered Jan 20 '13 at 04:03

2

4 * which == which << 2, so you can use that.

answered Jan 20 '13 at 04:03

fge

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ah, you're correct. so easy I overlooked it :P Thanks! – Evan LaHurd Jan 20 '13 at 04:04
Of course, this is subject to overflows ;) – fge Jan 20 '13 at 04:06
Any more then `4 * which`? – Miserable Variable Jan 20 '13 at 04:25
No, in fact internally the JVM will eventually do the same -- shifting is faster – fge Jan 20 '13 at 04:35

What are some alternatives to multiplication in Java?

1 Answers1