Question

我不知道如何在没有这种方法的情况下获得中位数，但它一直在说转换错误。我知道这是因为我将numbers.length除以2，但我无法弄清楚如何让程序理解它是双倍的。它位于我不断收到错误的底部。这是我最后的if else声明。我到处搜索所以如果这是重复我很抱歉，但我找不到一个。我无法转换为整数，因为我的数组包含双精度数。提前感谢帮助我的人。

import static java.lang.Math.*;
import java.util.Scanner;
import java.util.Arrays;
public class ComputingArrays
{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        double [] numbers = {33.5, 67.5, 67.5, 88.0, 46.0, 94.5, 77.5, 83.0, 95.0, 80.5}; // declare, allocate memory, and store values

        double n = numbers.length; // get length of array
        Arrays.sort(numbers);
        System.out.println("The Array of Numbers are :");
        double sum = 0; //initiate and declare sum
        for (int i = 0; i < n; i++) {  //loop through n numbers
            System.out.println(numbers[i]);
            sum = sum + numbers[i];
        }      
        final double average = sum / n;
        System.out.println("The Sum of the Array is " + sum);
        System.out.println("The Average of the Array is " + average);

        double var1 = 0;
        double var2 = 0;
        double varSum = 0;
        for (int i = 0; i < n; i++) { 
            var1 = numbers[i] - average;            
            var2 = var1 * var1; // to square
            varSum = varSum + var2; // to get sum of all squared differences
        }
        double variance = varSum / n;
        System.out.printf("The Variance of the Array is  %.2f %n", variance); //%.2f rounds two decimal places 

        System.out.printf("The Standard Deviation is %.3f %n", Math.sqrt(variance));

        double middle = numbers.length / 2.0;
        double median = 0.0;
        if (numbers.length % 2 == 1){
            median = numbers[middle];
            System.out.println("The median is " + median);
        }
        else {
            median = (numbers[middle-1] + numbers[middle]) / 2;
            System.out.println("The median is " + median);
        }
    }
}

Answer 1

你应该将变量n设为int .Array length总是为int 你的问题是你正在使变量middle double.later将该变量称为索引号。但索引号只能是int。

Answer 2

索引数组时，它需要int而不是double，因为5.5之类的值不是有效索引。

<强>有效

int middle = numbers.length / 2;
System.out.println(numbers[middle]);

<强>无效

double middle = numbers.length / 2.0;
System.out.println(numbers[middle]);

Answer 3

import static java.lang.Math.*;
import java.util.Scanner;
import java.util.Arrays;
public class HelloWorld
{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        double [] numbers = {33.5, 67.5, 67.5, 88.0, 46.0, 94.5, 77.5, 83.0, 95.0, 80.5}; // declare, allocate memory, and store values

    double n = numbers.length; // get length of array
    Arrays.sort(numbers);
    System.out.println("The Array of Numbers are :");
    double sum = 0; //initiate and declare sum
    for (int i = 0; i < n; i++) {  //loop through n numbers
        System.out.println(numbers[i]);
        sum = sum + numbers[i];
    }      
    final double average = sum / n;
    System.out.println("The Sum of the Array is " + sum);
    System.out.println("The Average of the Array is " + average);

    double var1 = 0;
    double var2 = 0;
    double varSum = 0;
    for (int i = 0; i < n; i++) { 
        var1 = numbers[i] - average;            
        var2 = var1 * var1; // to square
        varSum = varSum + var2; // to get sum of all squared differences
    }
    double variance = varSum / n;
    System.out.printf("The Variance of the Array is  %.2f %n", variance); //%.2f rounds two decimal places 

    System.out.printf("The Standard Deviation is %.3f %n", Math.sqrt(variance));

    double middle = numbers.length / 2.0;
    double median = 0.0;
    int middleIndex = (int)middle;
    if (numbers.length % 2 == 1){
        median = numbers[middleIndex];
        System.out.println("The median is " + median);
    }
    else {
        median = (numbers[middleIndex-1] + numbers[middleIndex]) / 2;
        System.out.println("The median is " + median);
    }
}
}

打印出来：

阵列的总和是733.0
阵列的平均值为73.3
数组的方差为369.66
标准差为19.227
中位数为79.0

我有一个双打数组，我需要得到一个中位数，但它不断给我一个int转换错误

3 个答案: