java - 创建数组列表

Question

我想采用我当前的程序并将平均函数分离到主方法之外的方法中。我想将扫描仪抓取的数字存储到数组列表中，然后使用我的平均方法抓取这些数字并将这些数字平均在一起。然后输出平均值代替当前的 System.out.println 你的平均值是..

请帮我说明这一点。我很难理解这一切是如何结合在一起的。

import java.util.Scanner;

class programTwo {

public static void main (String[] args) {
    Scanner scan = new Scanner(System.in);
    double sum = 0;
    int count = 0;
    System.out.println ("Enter your numbers to be averaged:");
    String inputs = scan.nextLine();

    while (!inputs.contains("q")) {
        Scanner scan2 = new Scanner(inputs); // create a new scanner out of our single line of input

         {
            sum += scan2.nextDouble();
            count += 1;
            System.out.println("Please enter another number or press Q for your average");
        } 

        if(count == 21)
        {
            System.out.println("You entered too many numbers! Fail.");
            return;
        }
        inputs = scan.nextLine();
    }
    System.out.println("Your average is: " + (sum/count));
}
}

Answer 1

//added an import here
import java.util.ArrayList;
import java.util.Scanner;

class programTwo
{
    //main difference is the average calculation is done within a method instead of main
    public static void main( String[] args )
    {
        Scanner scan = new Scanner(System.in);
        ArrayList<Double> myArr = new ArrayList<Double>();
        double sum = 0;
        int count = 0;
        System.out.println("Enter a number to be averaged:");
        String inputs = scan.nextLine();

    while (!inputs.contains("q")) //input until user no longer wants to give input
    {

        if (count == 21)
        {
            break; //this command here jumps out of the input loop if there are 21
        }

        Scanner scan2 = new Scanner(inputs); // create a new scanner out of our single line of input
        myArr.add(scan2.nextDouble()); //simply adding to the array list
        count += 1;
        System.out.println("Please enter another number or press Q for your average");

        inputs = scan.nextLine();
    }
    Double average = calculate_average(myArr); //go to method calculate average, expect a double to be returned
    System.out.println("Your average is: " + average); 
}

private static Double calculate_average( ArrayList<Double> myArr ) //method definition
{
    Double Sum = 0.0; 
    for (Double number: myArr) //for loop that iterates through an array list
    {
        Sum += number; //add all the numbers together into a sum
    }
    return Sum / myArr.size(); //return the sum divided by the number of numbers in the array list
}
}

这应该有帮助。祝你好运:)