java如何防止应用程序在用户输入字符串而不是整数时计算n个数的平均值时崩溃

Question

这是我的密码

/*
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 */
package javaapplication2;

import java.util.Scanner;


/**write a java program that take  three Numbers as input and print the average of the numbers 
 * 
 *
 * @author takenoLAB
 */
public class Average {
  
    public static void main(String[] args) {
         Scanner  input = new Scanner(System.in);
         System.err.println("enter your numbers separated by ,");
    String n = input.nextLine();
    System.out.print("here is your average "+cal(n));
    }
    public static double cal(String data){
    String [] datas=data.split(",");
    double tota=0;
     double avr=0;
     try{
     for (int i=0;i<datas.length;i++){
         tota+=Integer.parseInt(datas[i]);
     }
      avr = tota/datas.length;
     }
    
     catch(Exception err){}
     return avr;
    }
    
   
    
}

Answer 1

只有在遇到整数时才使用此选项，将其添加到总数并增加计数器。结果将取决于实际存在的整数数量

public static double cal(String data) {
        String[] datas = data.split(",");
        double tota = 0;
        double avr = 0;
        int count = 0;

        for (String s: datas)
        {
            try{
                tota += Integer.parseInt(s);
                count++;
            } catch(NumberFormatException ne)
            {
                
            }
        }
        
        avr = tota / count;
        return avr;
    }

输出：

enter your numbers separated by ,
5,2,3,a,5
4
here is your average 3.75

Answer 2

可以使用StringUtils.isNumeric()方法。例如：

if(StringUtils.isNotBlank(s) && StringUtils.isNumeric(s)){
     tota += Integer.parseInt(s);
}

因此，它将只添加来自用户的有效输入，并忽略所有其他无效数据（空白、空格、非数字的字符串），并且不会发生异常