Isolate right most set bit

‘x = x & (-x)’ isolate right most set bit.

100            000001100100

-100            111110011100

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100 & -100 000000000100
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public class IsloateNthBit {

 public static int isolateRightMostNthBit(int num) {
  num = num & (-num);
  return num;
 }
}

Following is the junit test case.

import static org.junit.Assert.assertEquals;

import org.junit.Test;

public class IsloateNthBitTest {

 @Test
 public void test1(){
  assertEquals(IsloateNthBit.isolateRightMostNthBit(100), 4);
  assertEquals(IsloateNthBit.isolateRightMostNthBit(123), 1);
  assertEquals(IsloateNthBit.isolateRightMostNthBit(204), 4);
  assertEquals(IsloateNthBit.isolateRightMostNthBit(256), 256);
 }
}