main类型的方法（double []）不适用于参数（int []）

Question

I am trying to find a median of an array in Java.

I am getting the exception:

Exception in thread "main" java.lang.Error: Unresolved compilation problem:

The method median(double[]) in the type tez3 is not applicable for the arguments (int[])

at tez3.main(tez3.java:33)

My code is below. What is the problem? How can i print the double function ?

import java.util.Scanner;
import java.io.*;
import java.util.ArrayList;

public class tez3 {

    public static void main(String args[]) throws java.io.IOException {
        Scanner s = new Scanner(new File("C:\\tny\\Deneme1.txt"));
        int[] numberList = new int[10];
        int i = 0;
        int count = 0;
        int result = 0;
        while (s.hasNextInt()) {
            numberList[i++] = s.nextInt();
        }
        for (i = 0; i < numberList.length; i++) {
            System.out.println(+(i + 1) + ".Value: " + numberList[i]);
        }
        for (i = 0; i < numberList.length; i++) {
            count++;
        }

        for (i = 0; i < numberList.length; i++) {
            result += numberList[i];
        }

        System.out.println("Average of the Values is: " + result / count);
        System.out.println("Mode of the Values is: " + mode(numberList));
        System.out.println("Median of the Values is: " + median(numberList));
    }

    public static int mode(int numberList[]) {
        int maxValue = 0, maxCount = 0;

        for (int i = 0; i < numberList.length; ++i) {
            int count = 0;
            for (int j = 0; j < numberList.length; ++j) {
                if (numberList[j] == numberList[i]) {
                    ++count;
                }
            }
            if (count > maxCount) {
                maxCount = count;
                maxValue = numberList[i];
            }
        }

        return maxValue;
    }

    public double median(double[] numberList) {
        int factor = numberList.length - 1;
        double[] first = new double[(double) factor / 2];
        double[] last = new double[first.length];
        double[] middleNumbers = new double[1];
        for (int i = 0; i < first.length; i++) {
            first[i] = numbersList[i];
        }
        for (int i = numberList.length; i > last.length; i--) {
            last[i] = numbersList[i];
        }
        for (int i = 0; i <= numberList.length; i++) {
            if (numberList[i] != first[i] || numberList[i] != last[i]) {
                middleNumbers[i] = numberList[i];
            }
        }
        if (numberList.length % 2 == 0) {
            double total = middleNumbers[0] + middleNumbers[1];
            return total / 2;
        } else {
            return middleNumbers[0];
        }
    }
}

Answer 1

The problem is exactly what the error message says. Your method median() takes a double[] as parameter.

But when you're trying to call it you give it numberList as a parameter. But numberList is an int[], that is to say it is not a double[].

The easiest fix is to modify median() so that the parameter it takes is int[] rather than double[].

Answer 2

The problem is that you want to cast all elements in you int[] list to a double. If you don't want to change the parameters of median to int[] then my preferred way to deal with this is to overload the method and convert the arguments

So, it would be something like:

    public double median(int[] numberList) {
        double[] doubleList = new double[numberList.size()];
        for(int i=0; i<doubleList.size(); i++){
            doubleList[i] = (double)numberList[i];
        }
        return median(doubleList);
    }

If you did change the parameter of your original 'median' method, then you would just cast the numberList element each time you called it, ie

    first[i] = (double) numbersList[i];