integer to binary java

1int n = 1000;
2String s = Integer.toBinaryString(n);

1import java.util.*;
2import java.util.Scanner;
3public class IntegerToBinary
4{
5   public static void main(String[] args)
6   {
7      int num;
8      String str = "";
9      Scanner sc = new Scanner(System.in);
10      System.out.println("Please enter the a number : ");
11      num = sc.nextInt();
12      // convert int to binary java
13      while(num > 0)
14      {
15         int y = num % 2;
16         str = y + str;
17         num = num / 2;
18      }
19      System.out.println("The binary conversion is : " + str);
20      sc.close();
21   }
22}

1String binary = Integer.toBinaryString(num);

1public static String makeBinaryString(int n) {
2	StringBuilder sb = new StringBuilder();
3	while (n > 0) {
4    sb.append(n % 2);
5		n /= 2;
6	}
7  	sb.reverse();  	
8  	return sb.toString();
9}

1public class DecimalToBinaryExample2{    
2public static void toBinary(int decimal){    
3     int binary[] = new int[40];    
4     int index = 0;    
5     while(decimal > 0){    
6       binary[index++] = decimal%2;    
7       decimal = decimal/2;    
8     }    
9     for(int i = index-1;i >= 0;i--){    
10       System.out.print(binary[i]);    
11     }    
12System.out.println();//new line  
13}    
14public static void main(String args[]){      
15System.out.println("Decimal of 10 is: ");  
16toBinary(10);    
17System.out.println("Decimal of 21 is: ");  
18toBinary(21);    
19System.out.println("Decimal of 31 is: ");    
20toBinary(31);  
21}}    

1Integer.toString(100,8) // prints 144 --octal representation
2
3Integer.toString(100,2) // prints 1100100 --binary representation
4
5Integer.toString(100,16) //prints 64 --Hex representation