public interface ISimpleList { protected Node start; protected Node end ; public

Question

public interface ISimpleList {
  
   protected Node start;
protected Node end ;
public int size ;

   int size();
  
   /**
   * Add item e to the end of the list
   * @param e
   */
   void add(String e);

   /**
   * Get the element at position index
   *
   * @param index
   * @return
   */
   String get(int index);
  
   /**
   * Add item e at position index
   *
   * @param index
   * @param element
   */
   void add(int index, String e);
  
   /**
   * Remove the item at position index
   *
   * @param index
   */
   void remove(int index);
  
   /**
   * Remove any occurrences of element e from the list and return how many were removed
   *
   * @param e the element to remove
   * @return how many occurrences of e were removed
   */
   int remove(String e);
}

public class Project3 {

   /**
   * Read lines from the file and put each line into the list in reverse order
   *
   * @param filename the filename
   * @return A list containing the file contents in reverse order
   * (first line in file is last in list and last line in file is first in list)
   */
   static ISimpleList getFileContentsInReverse(String filename) {
       // your code here should interact with the list using only the ISimpleList methods
      
       //TODO:
       return null;
   }

   public static void main(String[] args) {
       // you can test your list here but I will not grade this code
   }

}

Explanation / Answer

public interface ISimpleList {
  
int size();
  
/**
* Add item e to the end of the list
* @param e
*/
void add(String e);
/**
* Get the element at position index
*
* @param index
* @return
*/
String get(int index);
  
/**
* Add item e at position index
*
* @param index
* @param element
*/
void add(int index, String e);
  
/**
* Remove the item at position index
*
* @param index
*/
void remove(int index);
  
/**
* Remove any occurrences of element e from the list and return how many were removed
*
* @param e the element to remove
* @return how many occurrences of e were removed
*/
int remove(String e);
}

-----------------------------------------------------------------------------------------------------------------------------------------------------------

public class ArrayBasedList implements ISimpleList{

   private String arr[];
   private int count;
  
   ArrayBasedList(){
       count = 0;
       arr = new String[4];
   }
  
   // O(1)
   public int size() {
       return count;
   }

   // O(n)
   private void ensureCapacity(){
       if(count == arr.length){
           String newArr[] = new String[2 * count];
           for(int i = 0; i < count; ++i){
               newArr[i] = arr[i];
           }
           arr = newArr;
       }
   }
  
   // O(1) amortized
   public void add(String e) {
       ensureCapacity();
       arr[count++] = e;
   }

   // O(1)
   public String get(int index) {
       if(index < count && index >= 0){
           return arr[index];
       }
       else{
           return null;
       }
   }

   // O(n)
   public void add(int index, String e) {
       if(index <= count && index >= 0){
           ensureCapacity();
           for(int i = count; i > index; --i){
               arr[i] = arr[i - 1];
           }
           arr[index] = e;
           ++count;
       }
   }

   // O(n)
   public void remove(int index) {
       if(index < count && index >= 0){
           for(int i = index; i < count - 1; ++i){
               arr[i] = arr[i + 1];
           }
           --count;
       }
   }

   // O(n)
   public int remove(String e) {
       int temp = 0;
       for(int i = 0; i < count; ++i){
           if(arr[i].equals(e)){
               remove(i);
               ++temp;
               --i;
           }
       }
       return temp;
   }

}

------------------------------------------------------------------------------------------------------------------------------------------------------

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Project3 {
/**
* Read lines from the file and put each line into the list in reverse order
*
* @param filename the filename
* @return A list containing the file contents in reverse order
* (first line in file is last in list and last line in file is first in list)
*/
   // O(n ^ 2)
static ISimpleList getFileContentsInReverse(String filename) {
ISimpleList list = new ArrayBasedList();
Scanner in = null;
try {
           in = new Scanner(new File(filename));
           while(in.hasNextLine()){
               list.add(0, in.nextLine());
           }
       } catch (FileNotFoundException e) {
           e.printStackTrace();
       }
finally{
   if(in != null){
       try{
           in.close();
       }
       catch(Exception e){
           e.printStackTrace();
       }
   }
}
return list;
}
public static void main(String[] args) {
   Scanner in = new Scanner(System.in);
   String fileName;
   System.out.print("Enter file name: ");
   fileName = in.nextLine();
ISimpleList list = getFileContentsInReverse(fileName);
System.out.println("content of " + fileName + " in reverse");
for(int i = 0; i < list.size(); ++i){
   System.out.println(list.get(i));
}
}
}

----------------------------------------------------------------------------------------------------------------------------------------------------

RandomFile.txt:

Hi
I am Ronado
From Portugal

-------------------------------------------------------------------------------------------------------------------------------------------------------------

Output;

Enter file name: randomFile.txt
content of randomFile.txt in reverse
From Portugal
I am Ronado
Hi

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