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How to get the value of a bit at a certain position from a byte?

Asked 2012-02-20T00:39:32.183
59

If I have a byte, how would the method look to retrieve a bit at a certain position?

Here is what I have know, and I don't think it works.

public byte getBit(int position) {
    return (byte) (ID >> (position - 1));
}

where ID is the name of the byte I am retrieving information from.

java byte bit
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1 Answer

130
public byte getBit(int position)
{
   return (ID >> position) & 1;
}

Right shifting ID by position will make bit #position be in the furthest spot to the right in the number. Combining that with the bitwise AND & with 1 will tell you if the bit is set.

position = 2
ID = 5 = 0000 0101 (in binary)
ID >> position = 0000 0001

0000 0001 & 0000 0001( 1 in binary ) = 1, because the furthest right bit is set.
answered 2012-02-20T00:46:04.203

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