长字符串数字相加

长字符串数字相加

import java.util.regex.Pattern;/** * @author clydelou * */public class Test {/** * @param args */public static String sum(String s, String t) {Pattern pattern = Pattern.compile("[0-9]+?");if (!pattern.matcher(s).matches() || !pattern.matcher(t).matches()) {System.out.println("Error");System.out.println("s = /""+s+"/", t = /""+t+"/"");return "";} else {StringBuilder sb = new StringBuilder();int length0 = s.length();int length1 = t.length();s = new StringBuilder(s).reverse().toString();t = new StringBuilder(t).reverse().toString();int min = (length0 > length1 ? length1 : length0);boolean flag = (length0 > length1 ? true : false);int temp = 0;for (int i = 0; i < min; i++) {char x = s.charAt(i);char y = t.charAt(i);int result = x - '0' + y - '0' + temp;int r1 = result % 10;temp = result / 10;sb.append(r1);}if (flag) {while (temp != 0 && min < length0) {int result = s.charAt(min) - '0' + temp;int r1 = result % 10;temp = result / 10;sb.append(r1);min++;}if (min < length0) {String str = s.substring(min, length0);sb.append(str);}if (temp != 0) {sb.append(temp);}} else {while (temp != 0 && min < length1) {int result = t.charAt(min) - '0' + temp;int r1 = result % 10;temp = result / 10;sb.append(r1);min++;}if (min < length1) {String str = t.substring(min, length1);sb.append(str);}if (temp != 0) {sb.append(temp);}}return sb.reverse().toString();}}public static void main(String[] args) {// TODO Auto-generated method stubString s = "21341234568787667776768685";String t = "557467674876856785678987464";String m = "999999999";String n = "999999999";System.out.println(sum(s, t));System.out.println(sum(t, s));System.out.println(sum(m, n));System.out.println(sum("a", "1"));}}