Question

IN JAVA PLEASE ASAP !!!

I just need the main and mergesort function

1. Ask the user for the number of elements, not to exceed arraySize = 20 (put appropriate input validation)
2. Ask the user for the type of data they will enter - EnglishGrade or MathGrade objects.
3. Use your EnglishGrade and MathGrade classes
4. Based on the input, create an appropriate array for the data to be entered.
5. Write a helper function called recursionMergeSort such that:
   • It is a standalone function not part of any Grade class
   • Takes in the same type of parameters as any standard MergeSort with recursion behavior, i.e.
     • void MergeSort(EnglishGrade arr[], int size)
   • Prints out how the array looks every time a recursive step returns back to its caller
   • You might need to pass in a third parameter which identifies the array to be printed - this is language dependent.
6. In your main, allow the user to enter data of their own choosing up to their chosen array size.
7. Then sort the array using your sort function (recursionMergeSort)
8. In your main, make sure that the output is being written to console as well as an output file at the same time.

EnglishGrade class:

public class EnglishGrade {

private int firstEnglishTestGrade;

private int secondEnglishTestGrade;

public EnglishGrade(int firstEnglishTestGrade, int secondEnglishTestGrade) {

super(firstEnglishTestGrade, secondEnglishTestGrade);

}

public EnglishGrade() {

super();

this.secondEnglishTestGrade = secondEnglishTestGrade;

this.firstEnglishTestGrade = firstEnglishTestGrade;

}

//getters

public int getfirstEnglishGrade() {

return firstEnglishTestGrade;

}

public int getsecondEnglishGrade() {

return secondEnglishTestGrade;

}

//setters

public void setfirstEnglishGrade(int firstEnglishTestGrade) {

this.firstEnglishTestGrade = firstEnglishTestGrade;

}

public void setsecondEnglishGrade(int secondEnglishTestGrade) {

this.secondEnglishTestGrade = secondEnglishTestGrade;

}

MathGrade Class:

public class MathGrade extends EnglishGrade {

private int firstMathTestGrade;

private int secondMathTestGrade;

public MathGrade(int firstMathTestGrade, int secondMathTestGrade) {

super(firstMathTestGrade, secondMathTestGrade);

}

public MathGrade() {

super();

this.secondMathTestGrade = secondMathTestGrade;

this.firstMathTestGrade = firstMathTestGrade;

}

//getters

public int getfirstMathGrade() {

return firstMathTestGrade;

}

public int getsecondMathGrade() {

return secondtMathTestGrade;

}

//setters

public void setfirstMathGrade(int firstMathTestGrade) {

this.firstMathTestGrade = firstMathTestGrade;

}

public void setsecondMathGrade(int secondtMathTestGrade) {

this.secondtMathTestGrade = secondtMathTestGrade;

}

Answer 1

Hello! :)

The code you gave didn't compile so I had to make some changes.

Here are the codes to solve the assignment:

EnglishGrade.java:

public class EnglishGrade {
    private int firstEnglishTestGrade;
    private int secondEnglishTestGrade;

    public EnglishGrade(int firstEnglishTestGrade, int secondEnglishTestGrade) {
        this.secondEnglishTestGrade = secondEnglishTestGrade;
        this.firstEnglishTestGrade = firstEnglishTestGrade;
    }

    public EnglishGrade() {
    }

    //getters
    public int getfirstEnglishGrade() {
        return firstEnglishTestGrade;
    }

    public int getsecondEnglishGrade() {
        return secondEnglishTestGrade;
    }

    //setters
    public void setfirstEnglishGrade(int firstEnglishTestGrade) {
        this.firstEnglishTestGrade = firstEnglishTestGrade;
    }

    public void setsecondEnglishGrade(int secondEnglishTestGrade) {
        this.secondEnglishTestGrade = secondEnglishTestGrade;
    }
}

MathGrade.java:

public class MathGrade extends EnglishGrade {
    private int firstMathTestGrade;
    private int secondMathTestGrade;

    public MathGrade(int firstMathTestGrade, int secondMathTestGrade) {
        super(firstMathTestGrade, secondMathTestGrade);
        this.secondMathTestGrade = secondMathTestGrade;
        this.firstMathTestGrade = firstMathTestGrade;
    }

    public MathGrade() {
        super();
    }

    //getters
    public int getfirstMathGrade() {
        return firstMathTestGrade;
    }

    public int getsecondMathGrade() {
        return secondMathTestGrade;
    }

    //setters
    public void setfirstMathGrade(int firstMathTestGrade) {
        this.firstMathTestGrade = firstMathTestGrade;
    }

    public void setsecondMathGrade(int secondtMathTestGrade) {
        this.secondMathTestGrade = secondtMathTestGrade;
    }
}

Main.java:

import java.io.BufferedReader;
import java.io.InputStreamReader;

import java.io.BufferedWriter;
import java.io.OutputStreamWriter;

import java.io.File;
import java.io.FileOutputStream;

import java.io.IOException;

public class Main
{
    public static void main(String[] args) throws IOException
    {
        // creating buffers
        br = new BufferedReader(new InputStreamReader(System.in));
        bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File("output.txt"))));

        // reading arraySize
        System.out.print("Enter the number of elements: ");
        int arraySize = Integer.parseInt(br.readLine());

        // validating arraySize
        if(arraySize > 20)
        {
            System.out.println("Error: You exceeded arraySize 20.");
            System.exit(1);
        }

        // reading type of data
        System.out.println("Types of data: ");
        System.out.println("1. EnglishGrade");
        System.out.println("2. MathGrade");
        System.out.print("Enter the type of data you want to enter: ");
        typeOfData = Integer.parseInt(br.readLine());

        // validating typeOfData
        if(typeOfData != 1 && typeOfData != 2)
        {
            System.out.println("Error: Invalid type.");
            System.exit(1);
        }

        // reading the data
        EnglishGrade[] arr = new EnglishGrade[arraySize];
        for(int i = 0; i < arr.length; ++i)
        {
            System.out.print("Enter first " + (typeOfData == 1 ? "English" : "Math") + " test grade: ");
            int firstGrade = Integer.parseInt(br.readLine());
            System.out.print("Enter second " + (typeOfData == 1 ? "English" : "Math") + " test grade: ");
            int secondGrade = Integer.parseInt(br.readLine());
            arr[i] = typeOfData == 1? new EnglishGrade(firstGrade, secondGrade) : new MathGrade(firstGrade, secondGrade);
        }

        // displaying the data
        System.out.println("Sorting:");

        bw.write("Sorting:");
        bw.newLine();

        for(int i = 0; i < arr.length; ++i)
        {
            System.out.println("First " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getfirstEnglishGrade() + "\tsecond " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getsecondEnglishGrade());

            bw.write("First " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getfirstEnglishGrade() + "\tsecond " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getsecondEnglishGrade());
            bw.newLine();
        }
        System.out.println();
        bw.newLine();

        // calling merge sort
        recursionMergeSort(arr, 0, arr.length - 1);

        // closing buffers
        br.close();
        bw.close();
    }

    // performs a recursive merge sort on arr[l, l+1, ..., r]
    public static void recursionMergeSort(EnglishGrade[] arr, int l, int r) throws IOException
    {
        if(l < r)
        {
            int mid = l + (r - l) / 2;
            recursionMergeSort(arr, l, mid);
            recursionMergeSort(arr, mid + 1, r);
            merge(arr, l, mid, r);

            for(int i = 0; i < arr.length; ++i)
            {
                System.out.println("First " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getfirstEnglishGrade() + "\tsecond " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getsecondEnglishGrade());
                bw.write("First " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getfirstEnglishGrade() + "\tsecond " + (typeOfData == 1 ? "English" : "Math") + " grade: " + arr[i].getsecondEnglishGrade());
                bw.newLine();
            }
            System.out.println();
            bw.newLine();
        }
    }

    // merges the sorted subarrays arr[l, l+1, ..., mid] and arr[mid+1, mid+2, ..., r]
    public static void merge(EnglishGrade[] arr, int l, int mid, int r)
    {
        // creating the auxilliary array
        EnglishGrade[] temp = new EnglishGrade[r - l + 1];
        for(int i = 0; i < r - l + 1; ++i)
        {
            temp[i] = new EnglishGrade();
        }

        // merging
        int k = 0;
        int i = l, j = mid + 1;
        while(i <= mid && j <= r)
        {
            if(arr[i].getfirstEnglishGrade() + arr[i].getsecondEnglishGrade()
                < arr[j].getfirstEnglishGrade() + arr[j].getsecondEnglishGrade())
            {
                temp[k].setfirstEnglishGrade(arr[i].getfirstEnglishGrade());
                temp[k].setsecondEnglishGrade(arr[i].getsecondEnglishGrade());
                ++i;
            }
            else
            {
                temp[k].setfirstEnglishGrade(arr[j].getfirstEnglishGrade());
                temp[k].setsecondEnglishGrade(arr[j].getsecondEnglishGrade());
                ++j;
            }
            ++k;
        }

        while(i <= mid)
        {
            temp[k].setfirstEnglishGrade(arr[i].getfirstEnglishGrade());
            temp[k].setsecondEnglishGrade(arr[i].getsecondEnglishGrade());
            ++i;
            ++k;
        }

        while(j <= r)
        {
            temp[k].setfirstEnglishGrade(arr[j].getfirstEnglishGrade());
            temp[k].setsecondEnglishGrade(arr[j].getsecondEnglishGrade());
            ++j;
            ++k;
        }

        // copying the data from the auxilliary array to the actual array
        for(k = 0; k < r - l + 1; ++k)
        {
            arr[k + l].setfirstEnglishGrade(temp[k].getfirstEnglishGrade());
            arr[k + l].setsecondEnglishGrade(temp[k].getsecondEnglishGrade());
        }
    }

    // member variables
    private static BufferedReader br;
    private static BufferedWriter bw;
    private static int typeOfData;
}

Output:

❯ javac EnglishGrade.java Main.java MathGrade.java
❯ java Main
Enter the number of elements: 5
Types of data: 
1. EnglishGrade
2. MathGrade
Enter the type of data you want to enter: 1
Enter first English test grade: 10
Enter second English test grade: 9
Enter first English test grade: 8
Enter second English test grade: 7
Enter first English test grade: 6
Enter second English test grade: 5
Enter first English test grade: 4
Enter second English test grade: 3
Enter first English test grade: 2
Enter second English test grade: 1
Sorting:
First English grade: 10 second English grade: 9
First English grade: 8  second English grade: 7
First English grade: 6  second English grade: 5
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 6  second English grade: 5
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 2  second English grade: 1
First English grade: 4  second English grade: 3

First English grade: 2  second English grade: 1
First English grade: 4  second English grade: 3
First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9

❯ cat output.txt
Sorting:
First English grade: 10 second English grade: 9
First English grade: 8  second English grade: 7
First English grade: 6  second English grade: 5
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 6  second English grade: 5
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 4  second English grade: 3
First English grade: 2  second English grade: 1

First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9
First English grade: 2  second English grade: 1
First English grade: 4  second English grade: 3

First English grade: 2  second English grade: 1
First English grade: 4  second English grade: 3
First English grade: 6  second English grade: 5
First English grade: 8  second English grade: 7
First English grade: 10 second English grade: 9

Hope this helps! :)