The java.math.BigInteger.setbit(index) method returns a Big-integer whose value is equivalent to this Big-integer with the designated bit set. The method computes (this | (1<<n)). The bit at index n of binary representation of Big-integer will be set means converted to 1.

Syntax: 

public BigInteger setbit(int n)

Parameters: The method takes one parameter n which refers to the index of the bit that is needed to be set.
Return Value: The method returns the BigInteger value after setting the bit position n.
Exceptions: The method might throw an ArithmeticException when n is negative..

Examples: 

Input: value = 2300 index = 1
Output: 2302
Explanation:
Binary Representation of 2300 = 100011111100
bit at index 1 is 0 so set the bit at index 1 
Now Binary Representation becomes 100011111110
and Decimal equivalent of 100011111110 is 2302

Input: value = 5482549 index = 1
Output: 5482551

Below program illustrate the setBit(index) method of BigInteger: 

// Program to demonstrate setBit() method of BigInteger 

import java.math.*;

public class GFG {

    public static void main(String[] args)
    {

        // Creating BigInteger object
        BigInteger biginteger = new BigInteger("2300");

        // Creating an integer i for index
        int i = 1;

        // Calling setBit() method on bigInteger at index i
        // store the return BigInteger
        BigInteger changedvalue = biginteger.setBit(i);

        String result = "After applying setBit at index " + 
        i + " of " + biginteger+ " New Value is " + changedvalue;

        // Displaying the result
        System.out.println(result);
    }
}

After applying setBit at index 1 of 2300 New Value is 2302

Reference: https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#setBit(int)