如何将数组传递给另一个类以查找最小值？

Question

I am trying to find the minimum value in an array by way of creating a new Java class. I am having trouble passing in the array and using it to find the minimum value of an array.

I have a total of two separate arrays that I am trying to find the value of.

Here is the first class I created:

import java.util.*;

public class mooseWeight
{
    public int main(String[] args)
    {
        int[] length1;
        int[] length2;

        length1 = new int[20];
        length2 = new int[50];

        //Length 1
        System.out.println("Array 1:");
        Random rnd = new Random();
        for(int i = 0; i<length1.length; i++)
        {
            length1[i] = rnd.nextInt(400) + 250;
            System.out.println(length1[i]);
            return length1[i];
        }

        System.out.println("-----------------------------------");

        //Length2
        System.out.println("Array 2:");
        Random rnd2 = new Random();
        for(int j = 0; j < length2.length; j++)
        {
            length2[j] = rnd2.nextInt(400) + 250;
            System.out.println(length2[j]);
            return length2[j];
        }
    }
}

This is currently set up to find the minimum value of length1[] (aka the first array).

This is the class I am trying to pass the arrays into:

public class minWeight
{
    public static int getArrayMin(int[] arr)
    {
        mooseWeight array1[] = new mooseWeight[];


        int minValue = array1[0];
        for (int i = 0; i < array1.length; i++) 
        {
            if (array1[i] < minValue) 
            {
                minValue = array1[i];
            }

            //return minValue;
        }
        return minValue;
        System.out.println(minValue);
    }
}

My current error:

1 error found:
File: D:\2016-2017\Fall2016\201_CSCE_Programming\Lab 7\minWeight.java  [line: 5]
Error: array dimension missing

Answer 1

Your mooseWeight class contains your main, so when you're creating array1 , you're trying to create an array containing your actual program.

mooseWeight array1[] = new mooseWeight[]; is creating an array of mooseWeight objects.

As you don't define a size, this will fail, but even if it didn't, it wouldn't work.

I assume that you meant to create an array of int , then loop over it.

If you created an array of int , then tried to loop over it without adding anything, the loop won't do anything as there's nothing to iterate over.

In your method, you pass in an array of int called arr , so you need to use that to loop over.

If you're trying to pass 2 arrays into the method, creating an array as part of your method still won't work.

You need to modify your method declaration to accept a second array.

Assuming you want to find the smallest value from both of these arrays, I've modified my code snippet to do just that. If you need to process your second array differently, modify the loop which deals with secondArr .

As mentioned in comments, your mooseWeight class should be named MooseWeight to keep with correct Java naming conventions.

A class name is in PascalCase, with instances in camelCase.

To call the method, use the following snippet.

int[] ar1 = new int[20];
int[] ar2 = new int[50];
//Populate your arrays with values....

int minValue = MinWeight.getArrayMin(ar1, ar2);

Class:

 public class MinWeight {
      public static int getArrayMin(int[] arr, int[] secondArr) {

        int minValue = arr[0];
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] < minValue) 
            {
                minValue = arr[i];
            }
         }

        for (int i = 0; i < secondArr.length; i++) {
            if (secondArr[i] < minValue) 
            {
                minValue = secondArr[i];
            }
         }          
        System.out.println(minValue);
        return minValue;
      }
    }

As a final concern, in your code, you return minValue before you try to print the result, so the print instruction is always unreachable.

Answer 2

The error in minWeight not fom the array parameter, it is from this line:

mooseWeight array1[] = new mooseWeight[];

You cannot allocate an array of unknown dimension in java. Also, your attempt to do so makes no sense. Just delete the line above from your java method and change the name of the parameter to array1.

Get an IDE like netbeans or eclipse.