Generate all the binary strings of N bits

// Java implementation of the above approach:
import java.util.*;

class GFG
{

// Function to print the output
static void printTheArray(int arr[], int n)
{
    for (int i = 0; i < n; i++) 
    {
        System.out.print(arr[i]+" ");
    }
    System.out.println();
}

// Function to generate all binary strings
static void generateAllBinaryStrings(int n, 
                            int arr[], int i)
{
    if (i == n) 
    {
        printTheArray(arr, n);
        return;
    }

    // First assign "0" at ith position
    // and try for all other permutations
    // for remaining positions
    arr[i] = 0;
    generateAllBinaryStrings(n, arr, i + 1);

    // And then assign "1" at ith position
    // and try for all other permutations
    // for remaining positions
    arr[i] = 1;
    generateAllBinaryStrings(n, arr, i + 1);
}

// Driver Code
public static void main(String args[])
{
    int n = 4;

    int[] arr = new int[n];

    // Print all binary strings
    generateAllBinaryStrings(n, arr, 0);
}
}

// This code is contributed by
// Surendra_Gangwar

public class Main {

    public static void main(String[] args)
    {
        int n = 4;
        // Loop over all possible combinations of n bits
        // using bit manipulation
        for (int i = 0; i < (1 << n); i++) {
            // Convert the integer 'i' to a binary string
            // representation of length 32 using the BitSet
            // class Note: Java's BitSet class does not have
            // a direct to_string() method like C++, so
            // we'll convert it to a binary string
            // representation using a custom method
            String binaryString = toBinaryString(i, n);
            System.out.println(binaryString);
        }
    }

    // Custom method to convert an integer 'num' to a binary
    // string representation of length 'length'
    static String toBinaryString(int num, int length)
    {
        StringBuilder sb = new StringBuilder();
        // Loop to append the binary digits to the
        // StringBuilder
        for (int i = length - 1; i >= 0; i--) {
            // Use bitwise AND operation to extract the
            // binary digit at position 'i'
            int bit = (num & (1 << i)) >> i;
            // Append the binary digit to the StringBuilder
            sb.append(bit);
        }
        return sb.toString();
    }
}