How to add big integers

/**
 * How to parse big numbers
 */
package com.belazy.algorithm;
/**
 *
 * @author vishnu prasad varma
 *
 */

public class StringToInt {
public static void main(String arg[]){
String s = "1234567";
String d = "23232323";
Double a = new Double(s);
Double b = new Double(d);
System.out.println(a.intValue() + b.intValue());
}

}