APCS/05 Collections _ Generics/04 IteratorLab/IteratorLab.java

 // Name: B6-24
 // Date: 12/11/19
 // use for-each loops or iterators, not regular for-loops
import java.io.*;
import java.util.*;
public class IteratorLab
{
   public static void main(String[] args)
   {
      System.out.println("Iterator Lab\n");
      int[] rawNumbers = {-9, 4, 2, 5, -10, 6, -4, 24, 20, -28};
      for(int n : rawNumbers )
         System.out.print(n + " ");    
      ArrayList<Integer> numbers = createNumbers(rawNumbers);
      System.out.println("\nArrayList: "+ numbers);      //Implicit Iterator!
      System.out.println("Count negative numbers: " + countNeg(numbers));
      System.out.println("Average: " + average(numbers));
      System.out.println("Replace negative numbers: " + replaceNeg(numbers));
      System.out.println("Delete zeros: " + deleteZero(numbers));
      String[] rawMovies = {"High_Noon", "High_Noon", "Star_Wars", "Tron", "Mary_Poppins", 
               "Dr_No", "Dr_No", "Mary_Poppins", "High_Noon", "Tron"};
      ArrayList<String> movies = createMovies(rawMovies);
      System.out.println("Movies: " + movies);
      System.out.println("Movies: " +  removeDupes(movies));
   }
      // pre: an array of just int values 
   	// post: return an ArrayList containing all the values
   public static ArrayList<Integer> createNumbers(int[] rawNumbers) 
   {
      ArrayList<Integer> list = new ArrayList<Integer>();
      for (int i = 0; i < rawNumbers.length; i++)
         list.add(rawNumbers[i]);
      return list;  
   }
      // pre: an array of just Strings  
   	// post: return an ArrayList containing all the Strings
   public static ArrayList<String> createMovies(String[] rawWords) 
   {
      ArrayList<String> myList = new ArrayList<String>();
      for ( String str : rawWords )
         myList.add( str );
      return myList;
   }
   
   	// pre: ArrayList a is not empty and contains only Integer objects
   	// post: return the number of negative values in the ArrayList a
   public static int countNeg(ArrayList<Integer> a)
   {
      Iterator<Integer> it = a.iterator(); int count = 0;
      while(it.hasNext())
         if (it.next() < 0)
              count++;
      return count;
   }
   	// pre: ArrayList a is not empty and contains only Integer objects
   	// post: return the average of all values in the ArrayList a
   public static double average(ArrayList<Integer> a)
   {
      Iterator<Integer> it = a.iterator(); double avg = 0;
      while(it.hasNext())
            avg += it.next();
            
      avg /= a.size();
      return avg;
   }
     	// pre: ArrayList a is not empty and contains only Integer objects
   	// post: replaces all negative values with 0 
   public static ArrayList<Integer> replaceNeg(ArrayList<Integer> a)
   {
      ListIterator<Integer> it = a.listIterator();
      while (it.hasNext())
         if (it.next() < 0)
            it.set(0);
      
      return a;
   }
     	// pre: ArrayList a is not empty and contains only Integer objects
   	// post: deletes all zeros in the ArrayList a
   public static ArrayList<Integer> deleteZero(ArrayList<Integer> a)
   {
       ListIterator<Integer> it = a.listIterator();
       while(it.hasNext())
         if (it.next() == 0)
            it.remove();
       
       return a;
   }
      // pre: ArrayList a is not empty and contains only String objects
   	// post: return ArrayList without duplicate movie titles
		// strategy: start with an empty array and add movies as needed
   public static ArrayList<String> removeDupes(ArrayList<String> a)
   {
       ArrayList<String> newList = new ArrayList<>(); ListIterator<String> it = a.listIterator();
       while(it.hasNext()) {
         String movie = it.next();
         if (!newList.contains(movie))
            newList.add(movie);
       }
       return newList;
   }
   
}