一阶段-secondwork-4-输入求和

/*
4、用户输入一个三位数，然后求一个三位数的各位和。如123，则1+2+3=6；233，则2+3+3=8.
*/

package secondwork;
import java.io.*;
/**
*
* @author Administrator
*/
public class Sum4
{
    InputStreamReader in = new InputStreamReader(System.in);
    BufferedReader buff = new BufferedReader(in);
    public Sum4()
    {
        System.out.println("请输入一个三位的整数：");
        try
        {
            int a = 0;
            int b = 0;
            int c = 0;
            String str = buff.readLine();
            int num = Integer.parseInt(str);
            if(num >=  100&& num <= 999)
             {
                 a =( num / 100) ;
                 if((num-a*100) >= 10)
                 {
                       b = (num - a*100) / 10;
                 }
                  if((num - a*100 -a*10) > 0)
                  {
                      c = num - a*100 -b*10;
                  }
             int sum = a + b + c;
             System.out.println(""+sum);
             }else if(num < 0 || num > 999){
                System.out.println("输入有错！请从新输入！");
             }
            
        }catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    public static void main(String[] args)
    {
        new Sum4();
    }
}