用堆栈实现长整数相加

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package com.michael.j2se;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Stack;

public class BigIntegerAdd {

    public static void main(String[] args) throws Exception {
        System.out.println("请输入第一个大数字");
        String s1 = input();
        System.out.println("请输入第二个大数字");
        String s2 = input();

        add(s1, s2);
    }

    private static void add(String s1, String s2) {
        Stack<Integer> st1 = new Stack<Integer>();
        Stack<Integer> st2 = new Stack<Integer>();
        Stack<Integer> result = new Stack<Integer>();
        int templen = 0;
        String strvalue = "";

        // 调整长度相同
        if (s1.length() >= s2.length()) {
            templen = s1.length() - s2.length();
            s2 = maxlen(s2, templen); // 208,2
        } else {
            templen = s2.length() - s1.length();
            s1 = maxlen(s1, templen);
        }

        try {
            for (int i = 0; i < s1.length(); i++) {
                st1.push(Integer.parseInt(String.valueOf(s1.charAt(i))));
                st2.push(Integer.parseInt(String.valueOf(s2.charAt(i))));

                // st1.push(s1.charAt(i) - '0');
                // st2.push(s2.charAt(i) - '0');
                int m = st1.pop() + st2.pop();
                result.push(m);
            }
        } catch (NumberFormatException e) {
            e.printStackTrace();
        }

        int temp = 0;
        while (!result.empty()) {
            int t = result.pop();
            if (t >= 10) {
                strvalue = String.valueOf(t + temp - 10) + strvalue;
                temp = t / 10;
            } else {
                strvalue = String.valueOf(t + temp) + strvalue;
                temp = 0;
            }
        }
        // 考虑最后一位进位
        if (temp != 0) {
            StringBuffer sb = new StringBuffer();
            sb.append(strvalue);
            strvalue = sb.insert(0, temp).toString();
        }
        display(strvalue);
    }

    /**
    * 接受输入
    *
    * @return
    */
    private static String input() {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = "";

        //这里可以用正则表达式验证输入的是否都为数字
        try {
            s = br.readLine();

        } catch (Exception e) {
            e.getMessage();
        }
        return s;
    }

    /**
    * 输出结果
    *
    * @param result
    */
    private static void display(String str) {
        System.out.print(str);
    }

    /**
    * 添0实现字符串长度一样
    * @param str
    * @param templen
    * @return
    */
    private static String maxlen(String str, int templen) {
        String strmax = null;
        StringBuffer buff = new StringBuffer();
        for (int i = 0; i < templen; i++) {
            buff.append("0");
        }
        strmax = buff.toString() + str;
        return strmax;

    }
}