static final int DONE = (1 << 9) - 1; ???

i was just looking over someone elses code and i came across the line of code
static final int DONE = (1 << 9) - 1;

could someone please example to me what the (1 << 9) -1 part it doing? ive not seen the << symbol used in any code before.

You will want to look up bit shifting to see what this does. Also, when I run across something I don't fully understand, I run little test programs to see what it does, i.e.,

Code:

---

public class Fu1 {
  public static void main(String[] args) {
      for (int i = 0; i < 12; i++) {
        int shiftedBit = (1 << i);
        System.out.printf("Shifted by %2d: %d%n",  i, shiftedBit);
      }
  }
}

---

<< just move bits to left.
It is also useful pair as >> too :)

byte boo=3<<1;

the code should move one bit to left I guess...


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