java 实现任意位数相加！

package com.ajax;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

/**

* @author xn14168

*

* TODO To change the template for this generated type comment go to

* Window - Preferences - Java - Code Style - Code Templates

*/

public class Test {

public static void main(String[] args) {

while(true) {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

String a = null;

String b = null;

try {

System.out.println("Number1:");

a = br.readLine();

System.out.println("Number2:");

b = br.readLine();

Object[] result = add(a, b);

System.out.println("Result : ");

for(int i=0; i < result.length; i++) {

System.out.print(result[i]);

}

System.out.println();

System.out.println("Continue?(Y/N)");

String exit = br.readLine();

if("N".equalsIgnoreCase(exit)) {

break;

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

private static Object[] add(String a, String b) {

String m = a;

String n = b;

if(a.length()>b.length()) {

n = padZero(b, a.length()-b.length());

} else {

m = padZero(a, b.length()-a.length());

}

System.out.println(m);

System.out.println(n);

long[] x = getNumberArray(m);

long[] y = getNumberArray(n);

return doAdd(x,y);

}

private static long[] getNumberArray(String number) {

int time = getTime(number);

if(time == 1 ) {

return new long[]{Long.parseLong(number)};

}

long[] result = new long[time];

String temp = number;

for(int i=time-1; i >=0; i-- ) {

if(temp.length() <=18) {

result[i] = Long.parseLong(temp);

} else {

String subNum = temp.substring(temp.length()-18, temp.length());

result[i] = Long.parseLong(subNum);

temp = temp.substring(0, temp.length()-18);

}

}

return result;

}

private static String padZero(String a, int zeroNum) {

StringBuffer sb = new StringBuffer();

for(int i = 0; i<zeroNum; i++) {

sb.append("0");

}

return sb.append(a).toString();

}

private static int getTime(String number) {

int length = number.length();

int time = (int)Math.ceil(length/18f);

return time;

}

private static Object[] doAdd(long[] a, long[] b) {

Object[] result=new Object[a.length];

int jinwei = 0;

for(int i = b.length-1; i>=0; i--) {

// System.out.print(a[i] + " + " + b[i] + " + " + jinwei);

result[i] = new Long(a[i] + b[i] + jinwei);

long longValue = ((Long)result[i]).longValue();

if( longValue >= 1000000000000000000l) {

jinwei = 1;

String temp = String.valueOf(longValue - 1000000000000000000l);

int needPad = 18 - temp.length();

result[i] = new String(padZero(temp, needPad));

} else if(i!=0) {

String temp = String.valueOf(longValue);

int needPad = 18 - temp.length();

result[i] = new String(padZero(temp, needPad));

jinwei = 0;

}

// System.out.println("= " + result[i]);

}

// if(jinwei == 1) {

// long longValue = ((Long)result[0]).longValue();

// result[0] = new Long(longValue + 1l);

// }

return result;

}

}