ArrayList Integer - 计算平均成绩而不考虑极值

Question

如何计算平均成绩（算术方法），从而将极端成绩（6）从列表中删除 - 而最小的（1）将从列表中删除？

import java.util.*;

import java.lang.*;

import java.io.*;

class ListOfGrades

{

    public static void main (String[] args) throws java.lang.Exception

    {

        //Create and fill the list 

        ArrayList<Integer> grades = new ArrayList<Integer>();

        grades.add(1);

        grades.add(2);

        grades.add(3);

        grades.add(4);

        grades.add(5);

        grades.add(6);

        for(int i=0; i < grades.size(); i++) {

            System.out.println("Element : [" + i + "] grades " +  grades.get(i)) ;  

        }

        System.out.println();

        System.out.println("Removing last Element");

        grades.remove(grades.size()-1);

        System.out.println("Now all grades are : " + grades);

        System.out.println();

        System.out.println("Removing first Element");

        grades.remove(grades.size()-5);

        System.out.println("Now all grades are : " + grades);

    }

}

Answer 1

您可以在之前编写的代码的末尾添加这个简单的代码：int sum=0;for (int i=0; i<grades.size();i++){&nbsp; &nbsp; sum+=grades.get(i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;//adding all the grades in variable sum}double avg= sum/grades.size();&nbsp; &nbsp; &nbsp; //dividing the sum with total number of&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //grades to calculate averageSystem.out.println("average grade :" + avg);&nbsp; &nbsp;&nbsp;

Answer 2

我试过这样的事情：&nbsp;grades.stream().filter(g&nbsp;->&nbsp;!(g&nbsp;==&nbsp;1&nbsp;||&nbsp;g&nbsp;==&nbsp;6)) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;.reduce((grade,&nbsp;sum)&nbsp;->&nbsp;grade&nbsp;+&nbsp;sum) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;.map(sum&nbsp;->&nbsp;sum&nbsp;/&nbsp;4) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;.orElse(0);

Answer 3

有使用Collectors::averagingDouble的流 api 解决方案：Double&nbsp;average&nbsp;=&nbsp;grades.stream() &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;.collect(Collectors.averagingDouble(value&nbsp;->&nbsp;value));