java入门实现转换

import java.io.*;
import java.util.Scanner;
public class shuru {

    /**
     * @param args
     */
    public static void main(String[] args) throws IOException{
        // TODO Auto-generated method stub
        System.out.println("请输入数字");    
        
            Scanner sc=new Scanner(System.in);//控制台输入
        
            String input=sc.nextLine();
            
            System.out.println("你输入的是"+input);
            
            input=input.trim();
        
            String[]temp=input.split(" ");
            
            double[]nums=new double[temp.length];//字符长度
            
            double aaa=0;//存放求和
        
            System.out.println("结果是");
            
            for(int i=0;i<temp.length;i++){
            
                nums[i]=Double.parseDouble(temp[i]);
                
                if(i==0)
                
                    System.out.print(nums[i]);
            
                
                else    if(nums[i]>0)
                
                    System.out.print("+"+nums[i]);
            
                else        if(nums[i]<0)
                    
                    System.out.print(nums[i]);
            
                else System.out.print("+"+nums[i]);
                
                aaa+=nums[i];
        }
    
            System.out.print("="+aaa);
    }
}