Question

import java.util.*;

/**
 * A class that implements the ADT set by using a linked bag.
 * The set is never full.
 *
 * 
 */
public class LinkedSetWithLinkedBag> implements SetInterface {
    private LinkedBag setOfEntries;

    /**
     * Creates a set from a new, empty linked bag.
     */
    public LinkedSetWithLinkedBag() {
        //TODO Project1
     

    } // end default constructor

    public boolean add(T newEntry) {
        //TODO Project1
         // new node is at beginning of chain
        if(this.setOfEntries.isEmpty()) {
            if (!this.setOfEntries.contains(newEntry))
            this.setOfEntries.add(newEntry);
        }

        return true;
       // return false; //THIS IS A STUB
    } // end add

    public T[] toArray() {
        //TODO Project1
        return null; //THIS IS A STUB
    } // end toArray

    public boolean isEmpty() {
        //TODO Project1
        return false; //THIS IS A STUB
    } // end isEmpty

    public boolean contains(T anEntry) {
        //TODO Project1
        return false; //THIS IS A STUB
    } // end contains

    public void clear() {
        //TODO Project1
    } // end clear

    public T remove() {
        //TODO Project1
        return null; //THIS IS A STUB
    } // end remove

    public boolean removeElement(T anEntry) {
        //TODO Project1
        return false; //THIS IS A STUB
    } // end remove

    // Displays a set.
    public void displaySet() {
        //TODO Project1
    } // end displaySet

    public static void main(String[] args) {
        String[] inputData = {"A", "B", "C", "D", "A", "C", "B", "B"};

        System.out.println("--> Creating set1 and adding to it elements from inputData: " + Arrays.toString(inputData));
        SetInterface set1 = new LinkedSetWithLinkedBag<>();
        for (int i = 0; i < inputData.length; i++) {
            set1.add(inputData[i]);
        }
        System.out.println("--> Calling displaySet method to display elements in set1");
        set1.displaySet();
        System.out.println("--> Calling displaySet method to display elements in set1 one more time");
        set1.displaySet();

        System.out.println("\n--> Clearing set1");
        set1.clear();
        set1.displaySet();
        System.out.println("--> set1 isEmpty returns: " + set1.isEmpty());

        System.out.println("\n--> Creating set2 and set3");
        SetInterface set2 = new LinkedSetWithLinkedBag<>();
        SetInterface set3 = new LinkedSetWithLinkedBag<>();

        System.out.println("\n--> Adding elements to set2");
        set2.add("A");
        set2.add("A");
        set2.add("B");
        set2.add("A");
        set2.add("C");
        set2.add("A");
        System.out.println("--> set2 after adding elements");
        set2.displaySet();

        System.out.println("\n--> Adding elements to set3");
        set3.add("A");
        set3.add("B");
        set3.add("B");
        set3.add("A");
        set3.add("C");
        set3.add("C");
        set3.add("D");
        System.out.println("--> set3 after adding elements");
        set3.displaySet();

        System.out.println("\n--> set2 contains \"A\": " + set2.contains("A"));
        System.out.println("--> set2 contains \"E\": " + set2.contains("E"));

        System.out.println("\n--> Removing \"B\" from set2");
        set2.removeElement("B");
        System.out.println("--> After removing \"B\" from set2, ");
        set2.displaySet();

        System.out.println("\n--> Removing random element from set2");
        String removed = set2.remove();
        System.out.println("--> set2.remove() returned: \"" + removed + "\"");
        set2.displaySet();

        System.out.println("\n--> Removing \"A\" from set2");
        set2.removeElement("A");
        System.out.println("--> After removing \"A\" from set2, ");
        set2.displaySet();

        System.out.println("\n--> Removing random element from set2");
        removed = set2.remove();
        System.out.println("--> set2.remove() returned: \"" + removed + "\"");
        set2.displaySet();

        System.out.println("\n--> Adding 4 elements to set2");
        set2.add("K");
        set2.add("L");
        set2.add("M");
        set2.add("N");
        System.out.println("--> After adding 4 elements to set2:");
        set2.displaySet();

        System.out.println("\n--> Trying to add duplicate element \"N\" to set2");
        set2.add("N");
        System.out.println("--> After adding a duplicate element \"N\" to set2");
        set2.displaySet();

        System.out.println("\nTrying to add null entry");
        String nullEntry = null;
        set2.add(nullEntry);
        System.out.println("--> set2 after adding:");
        set2.displaySet();
    } // end main
} // end LinkedSetWithLinkedBag

Sample Run:

--> Creating set1 and adding to it elements from inputData: [A, B, C, D, A, C, B, B]

--> Calling displaySet method to display elements in set1

The set contains 4 element(s), as follows:

D C B A

--> Calling displaySet method to display elements in set1 one more time

The set contains 4 element(s), as follows:

D C B A

--> Clearing set1

The set is empty

--> set1 isEmpty returns: true

--> Creating set2 and set3

--> Adding elements to set2

--> set2 after adding elements

The set contains 3 element(s), as follows:

C B A

--> Adding elements to set3

--> set3 after adding elements

The set contains 4 element(s), as follows:

D C B A

--> set2 contains "A": true

--> set2 contains "E": false

--> Removing "B" from set2

--> After removing "B" from set2,

The set contains 2 element(s), as follows:

C A

--> Removing random element from set2

--> set2.remove() returned: "C"

The set contains 1 element(s), as follows:

A

--> Removing "A" from set2

--> After removing "A" from set2,

The set is empty

Answer 1

Here is the answer...

CODE:

import java.util.*;
class Creation{
   static void displaySet(HashSet<String> set) {
       Iterator<String> i=set.iterator();
while(i.hasNext())
{
    System.out.print(i.next()+"\t");
}
   }
   public static void main(String[] args) {
       HashSet<String> set1 = new HashSet();
       set1.addAll(Arrays.asList(new String[] {"A","B","C","D","A","C","B","B"}));
       displaySet(set1);
       set1.clear();
       System.out.println("\nisEmpty() : " + set1.isEmpty());

       HashSet<String> set2 = new HashSet();
       HashSet<String> set3 = new HashSet();
       set2.add("C");
       set2.add("B");
       set2.add("A");
       displaySet(set2);

       System.out.println();
       set3.addAll(Arrays.asList(new String[] {"D","C","B","A"}));
       displaySet(set3);
       System.out.println("\ncontains A : " + set2.contains("A"));      
       System.out.println("\ncontains E : " + set2.contains("E"));
       set2.remove("B");
       displaySet(set2);

       System.out.println();
       set2.remove("C");       //we have to pass object to remove method it doesn't remove random elements
       displaySet(set2);

       System.out.println();
       set2.remove("A");
       System.out.println("Finally set2 isEmpty: "+set2.isEmpty());
   }
}

OUTPUT:

0:45. C:\Windows\system32\cmd.exe C:\Users\sai Desktop>javac Creation.java Note: Creation.java uses unchecked or unsafe operations. Note: Recompile with -Xlint: unchecked for details. C:\Users\sai\Desktop>java Creation A B C D isEmpty() : true A B C A B C contains A: true contains E: false Finally set2 isEmpty: true C:\Users\sai\Desktop>

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