Question

JAVA PROGRAMMING PLEASE

This lab has three parts:

1. Create an ArrayList class.
2. Create a LinkedList class.
3. Print out the results after testing each of the methods in both of the classes and solving a simple problem with them.

Task 1 – ArrayList Class

Create an ArrayList class. This is a class that uses an internal array, but manipulates the array so that the array can be dynamically changed. This class should contain a default and overloaded constructor, where the default constructor creates an empty array and the overloaded constructor creates one with a size specified by the parameter.

There should also be a method that adds new elements to the array, which handles resizing and creation of the array if needed. As well as a method to remove elements from the array, which also handles resizing if needed. Finally, there should be a method that is able to retrieve an element at a given position in the internal array.

Task 2 – LinkedList Class

Create a LinkedList class. This is a class that uses references to create a list like structure. This class should have a default constructor that creates an empty list.

We will also need a method that adds elements to the list and handles resizing and creation if needed. There should be a removal method and a method that gets elements at any given point in the list.

Task 3 – The Tester Class

            Create a Tester Class, with a Main method. In the Main method, create one ArrayList and LinkedList object each. Use their addition, removal and get methods and show the results by printing the lists before and after each method call. Use user input to populate the lists, with at most ten inputs. After testing the methods, create two new methods, one that takes an ArrayList and one that takes in a LinkedList, and returns the sum of all the elements inside of each.

∃ Some Sample Output:

ArrayList Portion:

Enter a number: 5

Are you done entering numbers (y/n)? n

Enter a number: 9

Are you done entering numbers (y/n)? n

Enter a number: 11

Are you done entering numbers (y/n)? n

Enter a number: 7

Are you done entering numbers (y/n)? y

Initial contents of the list: 5, 9, 11, 7

Contents before adding another item: 5, 9, 11, 7

Please enter another number to add: 21

Contents after adding another item: 5, 9, 11, 7, 21

Contents before removing an item: 5, 9, 11, 7, 21

Please enter the index of the element to remove: 2

Contents after removing an item: 5, 9, 7, 21

Contents before retrieving a value from the list: 5, 9, 7, 21

Please enter the index of the element to retrieve: 0

Element at position 0 is: 5

Contents after retrieving a value from the list: 5, 9, 7, 21

Assume similar input for the LinkedList Portion.

Sum of all items in the ArrayList: 42

Sum of all items in the LinkedList: 42

Answer 1

IList.java

public interface IList<T> {

  void Add(T value);

  void Add(T value, int index);

  T Get(int index);

  T Remove();

  T Remove(int index);

  void Set(T value, int index);

  int getSize();

}

ArrayList.java

import java.util.Arrays;

public class ArrayList<T> implements IList<T> {

  private Object[] array;

  public int getSize() {

    return array.length;

  }

  public ArrayList() {

    array = new Object[0];

  }

  public ArrayList(int size) {

    array = new Object[size];

  }

  public void Add(T value) {

    Add(value, array.length);

  }

  public void Add(T value, int index) {

    if (index > array.length)

      throw new IndexOutOfBoundsException();

    array = Arrays.copyOf(array, array.length + 1);

    for (int i = index; i < array.length - 1; i++) {

      // shifting ahead

      array[i + 1] = array[i];

    }

    array[index] = value;

  }

  public void Set(T value, int index) {

    if (index >= array.length)

      throw new IndexOutOfBoundsException();

    array[index] = value;

  }

  public T Get(int index) {

    @SuppressWarnings("unchecked")

    final T t = (T) array[index];

    return t;

  }

  public T Remove(int index) {

    if (index >= array.length)

      throw new IndexOutOfBoundsException();

    var value = Get(index);

    var lastValue = array[array.length - 1];

    array = Arrays.copyOf(array, array.length - 1);

    for (int i = index; i < array.length - 1; i++) {

      // shifting behind

      array[index] = array[index + 1];

    }

    array[array.length - 1] = lastValue;

    return value;

  }

  public T Remove() {

    return Remove(array.length - 1);

  }

}

LinkedList.java

public class LinkedList<T> implements IList<T> {

  class Value<E> {

    public E value;

    public Value<E> next;

  }

  Value<T> head;

  private int Size = 0;

  public int getSize() {

    return Size;

  }

  public LinkedList() {

  }

  public LinkedList(int size) {

    head = new Value<T>();

    var last = head;

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

      last.next = new Value<T>();

      last = last.next;

    }

    Size = size;

  }

  private Value<T> gotoPosition(int index) {

    int currentIndex = 0;

    var last = head;

    while (last.next != null && currentIndex < index) {

      last = last.next;

      currentIndex++;

    }

    if (currentIndex != index) {

      throw new IndexOutOfBoundsException();

    }

    return last;

  }

  public void Add(T value) {

    Add(value, Size);

  }

  public void Add(T value, int index) {

    if (head == null && index == 0) {

      head = new Value<T>();

      head.value = value;

      Size++;

      return;

    }

    if (index == Size) {

      index--;

    }

    var last = gotoPosition(index);

    var newNode = new Value<T>();

    newNode.value = value;

    newNode.next = last.next;

    last.next = newNode;

    Size++;

  }

  public T Get(int index) {

    var last = gotoPosition(index);

    return last.value;

  }

  public T Remove() {

    return Remove(Size - 1);

  }

  public T Remove(int index) {

    int currentIndex = 0;

    var last = head;

    var secondLast = last;

    while (currentIndex != index && last.next != null) {

      secondLast = last;

      last = last.next;

      currentIndex++;

    }

    if (currentIndex == index) {

      var value = last.value;

      secondLast.next = last.next;

      Size--;

      return value;

    } else {

      throw new IndexOutOfBoundsException();

    }

  }

  public void Set(T value, int index) {

    var last = gotoPosition(index);

    last.value = value;

  }

}

TesterClass.java

import java.text.MessageFormat;

import java.util.Scanner;

public class TesterClass {

  static Scanner in;

  public static void main(String[] args) {

    in = new Scanner(System.in);

    System.out.println("Testing array list");

    ArrayList<Integer> arrayList = new ArrayList<>();

    TestList(arrayList);

    System.out.println(MessageFormat.format("Sum of all items in the ArrayList: {0}", getSum(arrayList)));

    System.out.println("Testing linked list");

    LinkedList<Integer> linkedList = new LinkedList<>();

    TestList(linkedList);

    System.out.println(MessageFormat.format("Sum of all items in the LinkedList: {0}", getSum(linkedList)));

    in.close();

  }

  public static void TestList(IList<Integer> list) {

    getUserInput(list);

    System.out.print("Initial content of list: ");

    printList(list);

    System.out.print("Contents before adding another item: ");

    printList(list);

    System.out.print("Please enter another number to add: ");

    list.Add(Integer.parseInt(in.nextLine()));

    System.out.print("Contents after adding another item: ");

    printList(list);

    System.out.print("Contents before removing an item: ");

    printList(list);

    System.out.print("Please enter the index of the element to remove: ");

    list.Remove(Integer.parseInt(in.nextLine()));

    System.out.print("Contents after removing an item: ");

    printList(list);

    System.out.print("Contents before retrieving a value from the list: ");

    printList(list);

    System.out.print("Please enter the index of the element to retrieve: ");

    int index = Integer.parseInt(in.nextLine());

    System.out.println(MessageFormat.format("Element at position {0} is: {1}", index, list.Get(index)));

    System.out.print("Contents after retrieving a value from the list: ");

    printList(list);

  }

  static void printList(IList<Integer> list) {

    for (int i = 0; i < list.getSize(); i++) {

      System.out.print(list.Get(i) + " ");

    }

    System.out.println();

  }

  static void getUserInput(IList<Integer> list) {

    boolean doneEntering = false;

    int count = 0;

    while (!doneEntering && count < 10) {

      System.out.print("Enter a number:");

      list.Add(Integer.parseInt(in.nextLine()));

      System.out.print("Are you done entering numbers (y/n)? ");

      doneEntering = in.nextLine().equals("y") ? true : false;

      ++count;

    }

  }

  static int getSum(IList<Integer> list) {

    int sum = 0;

    for (int i = 0; i < list.getSize(); i++) {

      sum += list.Get(i);

    }

    return sum;

  }

}

Output

Testing array list
Enter a number:5
Are you done entering numbers (y/n)? n
Enter a number:9
Are you done entering numbers (y/n)? n
Enter a number:11
Are you done entering numbers (y/n)? n
Enter a number:7
Are you done entering numbers (y/n)? y
Initial content of list: 5 9 11 7
Contents before adding another item: 5 9 11 7
Please enter another number to add: 21
Contents after adding another item: 5 9 11 7 21
Contents before removing an item: 5 9 11 7 21
Please enter the index of the element to remove: 2
Contents after removing an item: 5 9 7 21
Contents before retrieving a value from the list: 5 9 7 21
Please enter the index of the element to retrieve: 0
Element at position 0 is: 5
Contents after retrieving a value from the list: 5 9 7 21
Sum of all items in the ArrayList: 42
Testing linked list
Enter a number:5
Are you done entering numbers (y/n)? n
Enter a number:9
Are you done entering numbers (y/n)? n
Enter a number:11
Are you done entering numbers (y/n)? n
Enter a number:7
Are you done entering numbers (y/n)? y
Initial content of list: 5 9 11 7
Contents before adding another item: 5 9 11 7
Please enter another number to add: 21
Contents after adding another item: 5 9 11 7 21
Contents before removing an item: 5 9 11 7 21
Please enter the index of the element to remove: 2
Contents after removing an item: 5 9 7 21
Contents before retrieving a value from the list: 5 9 7 21
Please enter the index of the element to retrieve: 0
Element at position 0 is: 5
Contents after retrieving a value from the list: 5 9 7 21
Sum of all items in the LinkedList: 42

Hope this helps :)