Find the binary string of a long value with bitwise operator (Java)

list_all_combination.java

// "static void main" must be defined in a public class.
public class Main {
    public static void main(String[] args) {
        listItem(new String[] {"A","B","C","D","E","F"});
    }
    
    static public void listItem(String[] names) {
        int n = names.length;
        for (int c=0;c<Math.pow(2,n);c++) {
            System.out.print("{");
            boolean firstItem = true;
            for (int i=0;i<n;i++) {
                if (((c>>i)&1)==1) {
                    System.out.print((firstItem?"":",")+names[i]);
                    firstItem = false;
                }
            }
            System.out.println("}");
        }
    }
}

most_left_bit.java

public class MyClass {
    public static void main(String args[]) {
        
        int noOfBit = 9;
        
        long mlb = (long)Math.pow(2,noOfBit-1);
        for (long l=0;l<Math.pow(2,noOfBit);l++) {
            for (int b=0;b<noOfBit-1;b++) {
                System.out.print(((l<<b)&mlb)==mlb?1:0);
            }
            System.out.print(((l<<(noOfBit-1))&mlb)==mlb?1:0);
            System.out.println(":"+l);
        }
    }
}

with_char_array.java

public class MyClass {
    public static void main(String args[]) {
        
        int zero = '0'; //ascii code for character '0'
        //char c = (char)a;
        
        int noOfBit = 9;

        char[] binaryString = new char[noOfBit];
        
        for (int l=0;l<Math.pow(2,noOfBit);l++) {
            for (int b=0;b<noOfBit;b++) {
                //binaryString[noOfBit-b-1] = ((l>>b)&1)==1?'1':'0';
                binaryString[noOfBit-b-1] = (char)(((l>>b)&1)+zero);
            }
            System.out.println(new String(binaryString)+":"+l);
        }
    }
}