How can I sort using two different packages?

Question

I had an assignment for a class where I had to develop a simple number sort program.

My main is supposed to receive the user input and my sort class is supposed to interrupt and spit out the resulting numbers in ascending and descending order. The problem is that my main is taking the input but it's not putting it in order at all and I'm unsure why.

package main;
import sort.Sort;
import java.util.Scanner;
public class Main {

   public static void main(String[] args) {
       int arr[] = new int[5]; 
       Scanner myScanner = new Scanner(System.in);
       for(int i=0; i<5; i++) {
       System.out.print("Enter a number: ");
       myScanner.nextLine();
       }
       Sort sortObj = new Sort();
       sortObj.ascendingsort(arr);
   }
       
}

package sort;

public class Sort {

   public void ascendingsort(int arr[])
   {
       int n = arr.length;
               
       for (int i = 0; i < n-1; i++)
       {
           int min_idx = i;
           for (int j = i+1; j < n; j++)
               if (arr[j] < arr[min_idx])
                   min_idx = j;
           int temp = arr[min_idx];
           arr[min_idx] = arr[i];
           arr[i] = temp;
       }
   }
   void descendingsort(int arr[])
   {
       int n = arr.length;
       
       for (int i = 0; i < n-1; i++)
       {
           int min_idx = i;
           for (int j = i+1; j < n; j++)
               if (arr[j] < arr[min_idx])
                   min_idx = j;
           int temp = arr[min_idx];
           arr[min_idx] = arr[i];
           arr[i] = temp;
   
       }
   }
}

I know I'm missing something in my Main, because I'm fairly certain I don't need to put anything else into the sort class.

Answer 1

You're code is perfect. You just missed one assignment in your main method.

Instead of myScanner.nextLine(); you should have written arr[i] = myScanner.nextLine();

myScanner.nextLine(); is getting the next line you enter in the console but it isn't saving it anywhere. arr[i] = myScanner.nextLine(); will save the value of the console in the arr array.

Everything else should work after that.

Answer 2

First you are getting user input using myScanner.nextLine() but not storing it. myScanner.nextLine() won't save anything which user enters . Thus you need to store it in an array and then use it later. So your main method after the changes should be like this.

public static void main(String[] args) {
    int arr[] = new int[3];
    Scanner myScanner = new Scanner(System.in);
    for(int i=0; i<3; i++) {
        System.out.print("Enter a number: ");
        arr[i] = myScanner.nextInt();
    }
     Sort sortObj = new Sort();
     sortObj.ascendingsort(arr);
}

And your sorting functions are also wrong. There you do some mis-calculations and return / log nothing. Thus you will not see anything in the console if you are not logging or returning anything.

public void  descendingsort(int array[]) {

    int n = array.length;
    int i, j, temp;
    for (i = 0; i < ( n- 1 ); i++) {
        for (j = 0; j < n - i - 1; j++) {
            if (array[j] < array[j+1])
            {
                temp = array[j];
                array[j] = array[j+1];
                array[j+1] = temp;
            }
        }
    }
    for (i = 0; i < n; i++){
        System.out.println(array[i]);
    }
}


    public void ascendingsort(int array[]) {
    int n = array.length;
    int i, j, temp;
    for (i = 0; i < ( n- 1 ); i++) {
        for (j = 0; j < n - i - 1; j++) {
            if (array[j] > array[j+1])
            {
                temp = array[j];
                array[j] = array[j+1];
                array[j+1] = temp;
            }
        }
    }
    for (i = 0; i < n; i++){
        System.out.println(array[i]);
    }
}

I hope this functions will work for your use case of ascending and descending sort.