package com.duapp.itfanr;import java.math.*;import java.util.Arrays;public class CharDemo {	public static void main(String args[]) {		String num1 = "1234";		String num2 = "789";//此处没有考虑到负数情况		System.out.print(plusBigNum(num1, num2));	}	static String plusBigNum(String num1, String num2) {		int len1 = num1.length();		int len2 = num2.length();		// 格式化两个数，使之长度相同		if (len1 > len2) {			for (int i = 0; i < len1 - len2; i++) {				num2 = "0" + num2;			}		} else if (len2 > len1) {			for (int i = 0; i < len2 - len1; i++) {				num1 = "0" + num1;			}		}		int[] numArr1 = str2IntArr(num1);		int[] numArr2 = str2IntArr(num2);		int[] result = add(numArr1, numArr2);		StringBuffer sb = new StringBuffer();		for (int i = 0; i < result.length; i++) {			if (result[result.length-1] ==0 &&i==result.length-1){				break ; 						}			else sb.append(result[i]);		}		return sb.reverse().toString();	}	static int[] str2IntArr(String str) {		StringBuffer sb = new StringBuffer(str);		String rvsstr = sb.reverse().toString();		int len = rvsstr.length();		int[] out = new int[len];		for (int i = 0; i < len; i++) {			out[i] = Integer.parseInt(rvsstr.charAt(i) + "");		}		return out;	}	public static int[] add(int a[], int b[]) {		int maxLen = a.length;		int[] sum = new int[maxLen + 1];		int d = 0; 		for (int i = 0; i < maxLen; i++) {			int tempSum = a[i] + b[i] + d;			sum[i] = tempSum % 10;			d = tempSum / 10; // 进位					}		return sum;	}}