Question

PLEASE READ ALL

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

(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);
   }

}

HERE IS GIVEN MAIN CLASS

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

//Java program

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 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
Student [] temp= new Student [10];
mergesort(myStudents , temp ,0 , 9);
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!");
}
}
public static void merge(Student a[],Student temp[],int l,int m,int r){
int temp_pos=l,size=r-l+1,left_end=m-1;
while(l<=left_end&&m<=r){
if(a[l].getName().compareTo(a[m].getName())<0)temp[temp_pos++]=a[l++];
else temp[temp_pos++]=a[m++];
}
while(l<=left_end)temp[temp_pos++]=a[l++];
while(m<=r)temp[temp_pos++]=a[m++];
for(int i=0;i<size;i++){
a[r]=temp[r];
r--;
}
}
public static void mergesort(Student a[],Student temp[],int l,int r){
if(l<r){
int mid=l+(r-l)/2;
mergesort(a,temp,l,mid);
mergesort(a,temp,mid+1,r);
merge(a,temp,l,mid+1,r);
}
}

}
//sample output

<terminated> Main (2) [Java Application] C: Program Files\Java\jdk1.8.0 151 bin javaw.exe Sort Test Passed!