Java笔试题：两个大数相乘

import java.util.Scanner;
public class BigMultiTest {

public static void main(String[] args){
Scanner reader=new Scanner(System.in);
String numStr1=reader.next();
String numStr2=reader.next();

int[] intNum1=changetoArray(numStr1);
int[] intNum2=changetoArray(numStr2);

multiply(intNum1,intNum2);
}

public static int[] changetoArray(String numStr){
int length=numStr.length();
int[] intNum=new int[length];
for(int i=0;i<length;i++)
intNum[length-i-1]=Integer.parseInt(String.valueOf((numStr.charAt(i))));
return intNum;
}

public static int[] multiply(int[] num1,int[] num2){
int length1=num1.length;
int length2=num2.length;
int[] result=new int[length1+length2];
for(int i=0;i<length1;i++)
for(int j=0;j<length2;j++){
int temp = result[i + j] + num1[i] * num2[j];
result[i + j] = temp % 10;
result[i + j + 1] += temp / 10;
if (result[i + j + 1] > 10) {
result[i + j + 1] %= 10;
result[i + j + 2]++;
}
}
StringBuffer sb=new StringBuffer();
for(int i=result.length-1;i>=0;i--)
sb.append(result[i]);
System.out.println(sb.toString());
return result;
}
}