prerequisite : BigInteger Basics
The
java.math.BigInteger.testBit(index) method returns true if and only if the designated bit is set. This method Computes
(this & (1<<n)) != 0).
Syntax:
public boolean testBit(int n)
Parameter: The method takes one parameter
n of integer type which refers to the index of the bit that needs to be tested.
Return Value: The method returns true if and only if the designated bit is set else it will return false.
Exception: The method will throw an
ArithmeticException when n is negative.
Examples:
Input: BigInteger = 2300, n = 4
Output: true
Explanation:
Binary Representation of 2300 = 100011111100
bit at index 4 is 1 so set it means bit is set
so method will return true
Input: BigInteger = 5482549 , n = 1
Output: false
Below program illustrates the testBit() method of BigInteger.
Output:
The bit at index 3 of 2300 is set = true
Reference: https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#testBit(int) 
