解决大数字字符串变长的最佳方法是什么？

Question

I am working with a problem.The following code works for small string but in this case I have to work with long numbers.what could be the best possible solution ?

it gives error for very long string so how to approach to solve the best possible way. by the way it is UVA424. There are so many solution online .I like to solve my way so it is a portion of the code

import java.util.Scanner;

public class IntegerInquiry {

public static void main(String args[]) {
    Scanner input = new Scanner(System.in);
    long total = 0;
    while (input.hasNext()) {
        String i = input.next();
     if(i.equals("0"))  break; 

        int size = i.length();
        if(size <=100 ){
        long a = Long.parseLong(i);
        total = total+a;
        }



    }
    System.out.println(total);
 }
}

Answer 1

For big numbers you can use BigDecimal

    Scanner input = new Scanner(System.in);
    BigDecimal bigDecimal = new BigDecimal(0);
    while (input.hasNext()) {
        String i = input.next();
        if (i.equals("0"))
            break;
        bigDecimal = bigDecimal.add(new BigDecimal(i));
    }
    input.close();
    System.out.println("BigDecimal " + bigDecimal);
    System.out.println("Long " + bigDecimal.longValue()); // caution - narrowing