Question

How to create a bitset in Java

Answer 1

import java.util.BitSet;

public class BitSetExample {
    public static void main(String[] args) {
        // Create a BitSet with a default size
        BitSet bitSet = new BitSet();

        // Set some bits
        bitSet.set(0); // Set bit at index 0
        bitSet.set(2); // Set bit at index 2
        bitSet.set(4); // Set bit at index 4

        // Print the BitSet in reversed binary format
        System.out.println("BitSet:");
        printBitSet(bitSet, 16);
        
        // Check if a specific bit is set
        boolean isSet = bitSet.get(2);
        System.out.println("Is bit at index 2 set? " + isSet);

        // Clear a bit
        bitSet.clear(2);
        System.out.println("BitSet after clearing bit at index 2:");
        printBitSet(bitSet, 16);
        
         // Get the number of bits set to true
        int cardinality = bitSet.cardinality();
        System.out.println("Number of bits set to true: " + cardinality);
    }

    // Function to print the BitSet as 0 and 1 in reverse order
    public static void printBitSet(BitSet bitSet, int size) {
        for (int i = size - 1; i >= 0; i--) { // Iterate in reverse order
            System.out.print(bitSet.get(i) ? "1" : "0");
        }
        System.out.println();
    }
}




/*
run:

BitSet:
0000000000010101
Is bit at index 2 set? true
BitSet after clearing bit at index 2:
0000000000010001
Number of bits set to true: 2

*/

 

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