Question

Given the Interface Code write a java class that implements this interface and show the working functionality in the main method:

public interface CustomList<T> {

    /**

     * This method should add a new item into the <code>CustomList</code> and should

     * return <code>true</code> if it was successfully able to insert an item.

     * @param item the item to be added to the <code>CustomList</code>

     * @return <code>true</code> if item was successfully added, <code>false</code> if the item was not successfully added (note: it should always be able to add an item to the list)

     */

    boolean add (T item);

   
    /**

     * This method should add a new item into the <code>CustomList</code> at the

     * specified index (thus shuffling the other items to the right). If the index doesn't

     * yet exist, then you should throw an <code>IndexOutOfBoundsException</code>.

     * @param index the spot in the zero-based array where you'd like to insert your

     *        new item

     * @param item the item that will be inserted into the <code>CustomList</code>

     * @return <code>true</code> when the item is added

     * @throws IndexOutOfBoundsException

     */

    boolean add (int index, T item) throws IndexOutOfBoundsException;

   
    /**

     * This method should return the size of the <code>CustomList</code>

     * based on the number of actual elements stored inside of the <code>CustomList</code>

     * @return an <code>int</code> representing the number of elements stored in the <code>CustomList</code>

     */

    int getSize();

   
    /**

     * This method will return the actual element from the <code>CustomList</code> based on the

     * index that is passed in.

     * @param index represents the position in the backing <code>Object</code> array that we want to access

     * @return The element that is stored inside of the <code>CustomList</code> at the given index

     * @throws IndexOutOfBoundsException

     */

    T get(int index) throws IndexOutOfBoundsException;

   
    /**

     * This method should remove an item from the <code>CustomList</code> at the

     * specified index. This will NOT leave an empty <code>null</code> where the item

     * was removed, instead all other items to the right will be shuffled to the left.

     * @param index the index of the item to remove

     * @return the actual item that was removed from the list

     * @throws IndexOutOfBoundsException

     */

    T remove(int index) throws IndexOutOfBoundsException;

}

Answer 1

here is the code ---

CustomList.java

public interface CustomList<T> {

/**

* This method should add a new item into the <code>CustomList</code> and should

* return <code>true</code> if it was successfully able to insert an item.

* @param item the item to be added to the <code>CustomList</code>

* @return <code>true</code> if item was successfully added, <code>false</code> if the item was not successfully added (note: it should always be able to add an item to the list)

*/

boolean add (T item);

/**

* This method should add a new item into the <code>CustomList</code> at the

* specified index (thus shuffling the other items to the right). If the index doesn't

* yet exist, then you should throw an <code>IndexOutOfBoundsException</code>.

* @param index the spot in the zero-based array where you'd like to insert your

* new item

* @param item the item that will be inserted into the <code>CustomList</code>

* @return <code>true</code> when the item is added

* @throws IndexOutOfBoundsException

*/

boolean add (int index, T item) throws IndexOutOfBoundsException;

/**

* This method should return the size of the <code>CustomList</code>

* based on the number of actual elements stored inside of the <code>CustomList</code>

* @return an <code>int</code> representing the number of elements stored in the <code>CustomList</code>

*/

int getSize();

/**

* This method will return the actual element from the <code>CustomList</code> based on the

* index that is passed in.

* @param index represents the position in the backing <code>Object</code> array that we want to access

* @return The element that is stored inside of the <code>CustomList</code> at the given index

* @throws IndexOutOfBoundsException

*/

T get(int index) throws IndexOutOfBoundsException;

/**

* This method should remove an item from the <code>CustomList</code> at the

* specified index. This will NOT leave an empty <code>null</code> where the item

* was removed, instead all other items to the right will be shuffled to the left.

* @param index the index of the item to remove

* @return the actual item that was removed from the list

* @throws IndexOutOfBoundsException

*/

T remove(int index) throws IndexOutOfBoundsException;

}

interfaceclass.java----

import java.util.*;
public class interfaceclass implements CustomList<String>
{
   /*
   the CustomList is the interface implements into class interfaceclass
now because the interface is public ,
then every method from the interface implemented here should be public
  
  
   */
ArrayList arr=new ArrayList(); //here i am using arraylist to perform the task

public boolean add(String item)
{
   // the add(String item) take input as string and return boolean value as true when the value add in the arraylist
   arr.add(item);
return true;  
}

public boolean add(int index, String item)
{
  
   // the add(int index,String item) take input as string and index as int and return boolean value as true when the value add in the arraylist
   arr.add(index,item);
   return true;
}
public int getSize(){
   // the getSize() return the size of the arraylist
int size =arr.size();
return size;
}

public String get(int index)
{
   // the get(int index) return the item which is stored in the index in the arraylist
   String value=(arr.get(index)).toString();
   return value;
}

public String remove(int index)
{
   // the remove(int index) return the item which is remove from the index in the arraylist
   String removeitem=(arr.remove(index)).toString();
   return removeitem;
}

public static void main(String args[])
{
   interfaceclass i=new interfaceclass();
   // creating reference of class interfaceclass
   System.out.println("the value added : "+i.add("aditya")); // add string aditya and it will return true or false , and print also
   System.out.println("the value added : "+i.add("xyz"));// add string xyz and it will return true or false , and print also
   System.out.println("the value added : "+i.add("abc"));// add string abc and it will return true or false , and print also
   System.out.println("the value added : "+i.add(2,"kori g"));// add string kori at index 2 and it will return true or false , and print also
   int sizeoflist=i.getSize();
   System.out.println("the size of list : "+sizeoflist); // it will return the size of arraylist
   String valuelist=i.get(1);
   System.out.println("the value : "+valuelist); // return the value at index 1

   String removeitem=i.remove(1); // remove item from the index 1
   System.out.println("the remove item from list : "+removeitem);

}

}

here are snapshots ---

here all done ! the method also throw exception if found runtime error ... hope it will help you !

the best approach to do this task to create package and then store the files into it..the interface provide the code reusable.

thank you !