Check Whether a number is Duck Number or not java solution

Check Whether a number is Duck Number or not?

A Duck number is a number which has zeroes present in it, but there should be no zero present in the beginning of the number. For example 3210, 8050896, 70709 are all duck numbers whereas 02364, 03401 are not.

The task is to check whether the given number is a duck number or not.

Examples:

Input : 707069
Output : It is a duck number.
Explanation: 707069 does not contains zeros at the beginning.

Input : 02364
Output : It is not a duck number.
Explanation: in 02364 there is a zero at the beginning of the number.

Sample code:

/**
 *
 */

/**
 * @author Abhinaw.Tripathi
 *
 */
public class DuckeNumberApp
{
public static void main(String[] args)
{
String num1 = "1023";

        char first_digit1 = num1.charAt(0);
       
        if( check_duck(num1) > 0 && first_digit1 != '0')
            System.out.println("It is a duck number");
        else
            System.out.println("It is not a duck number");
}

public  static int check_duck( String num)
       {
       int len = num.length();
       int count_zero = 0 ;
       char ch;

       for(int i = 1;i < len ;i++)
       {    
           ch=num.charAt(i);
           if(ch=='0')
               count_zero++;
       }
       return count_zero ;
    }
}


Output:

It is a duck number