Question

MERGESORT ASSIGNMENT FOLLOW THE FORMAT

Modify the MergeSort code provided in class (if you find a mistake with it extra credit)

(https://repl.it/@ashokbasawapatna/MergeSortExample) to work with Students (No need for generic types, you will only write Main.java). Then use the compareTo method for strings in Java to sort the students in Alphabetical order via MergeSort.

1) Create an array of 10 students by hand. Make sure it's not in alphabetical order. ONLY USE LOWER CASES FOR NAMES (I'll only test with that).

2) Modify the MergeSort and Merge function prototypes to work with students

3) Inside the Merge function use compareTo to determine which one comes sooner in the alphabet.

If I have two strings a and b

String a="aba";

String b="abb";

String c="aba";

System.out.println(a.compareTo(b));

System.out.println(b.compareTo(a));

System.out.println(c.compareTo(a));

Will output

-1 1 0

Note anything less than zero means the calling object is before the passed object in the dictionary

Zero means they are equal

1 means the calling object is after the passed object in the dictionary

HERE IS THE GIVEN STUDENT CLASS

public final class Student
{
   private int schoolID;
   private String name;

   public Student(String namePassed,int schoolIDPassed)
   {
       schoolID= schoolIDPassed;
       name= namePassed;
   }

   public int getSchoolID()
   {
       return schoolID;
   }

   public void setSchoolID(int schoolIDPassed)
   {
       schoolID=schoolIDPassed;
   }

   public String getName()
   {
       return name;
   }

   public void setName(String namePassed)
   {
       name=namePassed;
   }

   public boolean equals(Object toCompare)
   {
   Student temp= (Student) toCompare;
       return(temp.getSchoolID()==schoolID);
   }
  
   public String toString()
   {
   String toReturn="name: "+name+" id: "+schoolID;
   return (toReturn);
   }

}

AND HERE IS THE GIVEN MAIN CLASS WE MUST USE

import java.util.Arrays;
class Main {
public static void main(String[] args) {
Student [] myStudents= new Student [10];
myStudents[0]=new Student("shenice",100);
myStudents[1]=new Student("bonnie", 200);
myStudents[2]=new Student("johnny",300);
myStudents[3]=new Student("olivia",400);
myStudents[4]=new Student("ashtrash",500);
myStudents[5]=new Student("jeter",600);
myStudents[6]=new Student("danielle",700);
myStudents[7]=new Student("rodrick",800);
myStudents[8]=new Student("jeter",900);
myStudents[9]=new Student("zoey",1000);

//INSERT YOUR CODE TO SORT HERE AND INSERT YOUR FUNCTIONS BELOW MAIN. DO NOT DELETE THE STUFF UNDER HERE!! i.e. call your function here to sort

if(myStudents[0].getName().equals("ashtrash")&&myStudents[1].getName().equals("bonnie")&&myStudents[2].getName().equals("danielle")&&myStudents[3].getName().equals("jeter")&&myStudents[4].getName().equals("jeter") && myStudents[5].getName().equals("johnny") && myStudents[6].getName().equals("olivia") &&myStudents[7].getName().equals("rodrick") && myStudents[8].getName().equals("shenice") &&myStudents[9].getName().equals("zoey"))
{
System.out.println("Sort Test Passed!");
}
else
{
System.out.println("Sort test failed! Check your code!");
}
}
  
//paste your functions down here!
}

Answer 1

import java.util.Arrays;

class Student {
    private int schoolID;
    private String name;

    public Student(String namePassed, int schoolIDPassed) {
        schoolID = schoolIDPassed;
        name = namePassed;
    }

    public int getSchoolID() {
        return schoolID;
    }

    public void setSchoolID(int schoolIDPassed) {
        schoolID = schoolIDPassed;
    }

    public String getName() {
        return name;
    }

    public void setName(String namePassed) {
        name = namePassed;
    }

    public boolean equals(Object toCompare) {
        Student temp = (Student) toCompare;
        return (temp.getSchoolID() == schoolID);
    }

    public String toString() {
        String toReturn = "name: " + name + " id: " + schoolID;
        return (toReturn);
    }

}

public class Main {

    public static Student[] merge(Student[] firstSplit, Student[] secondSplit) {
        Student[] toReturn = new Student[firstSplit.length + secondSplit.length];
        int firstIter = 0;
        int secondIter = 0;
        int index = 0;
        while (firstIter < firstSplit.length && secondIter < secondSplit.length) {
            if (firstSplit[firstIter].getName().compareTo(secondSplit[secondIter].getName()) < 0) {
                toReturn[index] = firstSplit[firstIter];
                firstIter++;
                index++;
            } else {
                toReturn[index] = secondSplit[secondIter];
                secondIter++;
                index++;
            }
        }
        while (firstIter < firstSplit.length) {
            toReturn[index] = firstSplit[firstIter];
            firstIter++;
            index++;
        }
        while (secondIter < secondSplit.length) {
            toReturn[index] = secondSplit[secondIter];
            secondIter++;
            index++;
        }

        return toReturn;
    }

    public static Student[] mergeSort(Student[] arrayToSort) {
        if (arrayToSort.length == 1) {
            return arrayToSort;
        }
        Student split1[];
        Student split2[];
        // find midepoint
        split1 = Arrays.copyOfRange(arrayToSort, 0, arrayToSort.length / 2);
        split2 = Arrays.copyOfRange(arrayToSort, arrayToSort.length / 2, arrayToSort.length);
        split1 = mergeSort(split1);
        split2 = mergeSort(split2);
        arrayToSort = merge(split1, split2);
        return arrayToSort;
    }

    public static void main(String[] args) {
        Student[] myStudents = new Student[10];
        myStudents[0] = new Student("shenice", 100);
        myStudents[1] = new Student("bonnie", 200);
        myStudents[2] = new Student("johnny", 300);
        myStudents[3] = new Student("olivia", 400);
        myStudents[4] = new Student("ashtrash", 500);
        myStudents[5] = new Student("jeter", 600);
        myStudents[6] = new Student("danielle", 700);
        myStudents[7] = new Student("rodrick", 800);
        myStudents[8] = new Student("jeter", 900);
        myStudents[9] = new Student("zoey", 1000);


        myStudents = mergeSort(myStudents);

        // INSERT YOUR CODE TO SORT HERE AND INSERT YOUR FUNCTIONS BELOW MAIN. DO NOT
        // DELETE THE STUFF UNDER HERE!! i.e. call your function here to sort

        if (myStudents[0].getName().equals("ashtrash") && myStudents[1].getName().equals("bonnie")
                && myStudents[2].getName().equals("danielle") && myStudents[3].getName().equals("jeter")
                && myStudents[4].getName().equals("jeter") && myStudents[5].getName().equals("johnny")
                && myStudents[6].getName().equals("olivia") && myStudents[7].getName().equals("rodrick")
                && myStudents[8].getName().equals("shenice") && myStudents[9].getName().equals("zoey")) {
            System.out.println("Sort Test Passed!");
        } else {
            System.out.println("Sort test failed! Check your code!");
        }
    }

}

Please upvote, as i have given the exact answer as asked in question. Still in case of any concerns in code, let me know in comments. Thanks!