Question

Assignment: A set is a collection of items without repetitions. The goal of this assignment is to implement a set as a data structure. Do the following.

1. (30 points) Starting with the template attached, implement a generic class Set(T) that maintains a set of items of generic type T using the class ArrayList(T) in the Java API. Your Set class must provide the following instance methods:

add: that adds a new item. (Ignore if already in the set.)

remove: that removes an item. (Ignore if not in the set.)

membership: that returns true if a given item is in the set and false otherwise.

toString: that returns a string with the list of the items in the set.

2. (30 points) Write a testSet class with a main() method that tests all the operations of the Set class above. That is, create an empty set A of integers, obtain from the user some integers and store some in A, display the set using toString(), obtain from the user some integers and remove them from A using remove(), display the set using toString(), obtain an integer from the user and check whether it is in A or not using membership() and display the result.

---

import java.util.*;

public class Set<T>{
    //data fields
    private ArrayList<T> myList;
    
    // constructors
    Set(){
        // CODE HERE
    }
    // other methods
    public void add(T item){
        // CODE HERE
    }
    public void remove(T item){
        // CODE HERE
    }
    public Boolean membership(T item){
        // CODE HERE
    }
    public String toString(){
        // CODE HERE
    }
}

Answer 1

//Set.java

import java.util.ArrayList;

public class Set<T> {

       //data fields

    private ArrayList<T> myList;

   

    // constructors

    Set(){

       myList = new ArrayList<T>();

    }

    // other methods

    public void add(T item){

       if(!membership(item))

             myList.add(item);

    }

    public void remove(T item){

       if(membership(item))

             myList.remove(item);

      

    }

    public Boolean membership(T item){

       for(int i=0;i<myList.size();i++)

             if(myList.get(i).equals(item))

                    return true;

       return false;

    }

    public String toString(){

       String str = "[ ";

       for(int i=0;i<myList.size()-1;i++)

       {

             str += myList.get(i).toString()+", ";

       }

      

       if(myList.size() > 0)

       {

             str += myList.get(myList.size()-1).toString();

       }

      

       str += " ]";

      

       return str;

    }

}

//end of Set.java

// TestSet.java

import java.util.Scanner;

public class TestSet {

       public static void main(String[] args) {

             // create an empty set A of integers

             Set<Integer> A = new Set<Integer>();

             Scanner scan = new Scanner(System.in);

             int num;

             System.out.println("Enter 10 integers to insert : ");

            

             // obtain from the user some integers and store some in A

             for(int i=0;i<10;i++)

             {

                    System.out.print("Enter integer-"+(i+1)+" : ");

                    num = scan.nextInt();

                    A.add(num);

             }

             //display the set using toString()

             System.out.println("Set : "+A);

            

             //obtain from the user some integers and remove them from A using remove()

             System.out.println("Enter 5 integers to remove : ");

             for(int i=0;i<5;i++)

             {

                    System.out.print("Enter integer-"+(i+1)+" : ");

                    num = scan.nextInt();

                    A.remove(num);

             }

            

             // display the set using toString()

             System.out.println("Set : "+A);

            

             // obtain an integer from the user

             System.out.print("Enter the integer to check if it is present in Set or not : ");

             num = scan.nextInt();

            

             // check whether it is in A or not using membership() and display the result.

             if(A.membership(num))

                    System.out.println(num+" is present in Set A");

             else

                    System.out.println(num+" is not present in Set A");

            

             scan.close();

       }

}

//end of TestSet.java

Output: