Set specific bit in byte

Question

I am trying to set bits in a Java byte variable. It provides methods like .setBit(i) . Does anyone know how I can figure this out?

I can iterate bit by bit over a given byte:

 if( (my_byte & (1 << i)) == 0 ){ } 

However, I cannot set this position to 1 or 0, can I?

Answer 1

Use the bitwise operators OR ( | ) and AND ( & ). To set the bit, namely, set the bit to pos 1 :

 my_byte = my_byte | (1 << pos); // longer version, or my_byte |= 1 << bit; // shorthand 

To clear a bit or set it to 0 :

 my_byte = my_byte & ~(1 << pos); // longer version, or my_byte &= ~(1 << bit); // shorthand 

For examples, see Advanced Java / Bitwise Operators.

Answer 2

To set the bit:

 myByte |= 1 << bit; 

To clear it:

 myByte &= ~(1 << bit); 

Answer 3

Just to complement John 's answer and driis's answer

To switch (invert) a bit

  myByte ^= 1 << bit; 

Answer 4

The necessary technique is to isolate the selected bit and set or clear it. You already have an expression to isolate the bit, since you use this to check it above. You can set the bit by its OR, or clear the bit by bit AND with 1 complement bit.

 boolean setBit; my_byte = setBit ? myByte | (1 << i) : myByte & ~(1 << i); 

Answer 5

See the java.util.BitSet class that does this work for you.

To install: myByte.set(bit); For reset: myByte.clear(bit); Fill in bool: myByte.set(bit, b); To get bool: b = myByte.get(bit); Get a bitmap: byte bitMap = myByte.toByteArray()[0];