Question

Java Programming

Exercise 32.13 Follow the instructions in the textbook, also shown here: 32.13 (Generic parallel merge sort) Revise Listing 30.10, ParallelMergeSort.java, to define a generic parallelMergeSort method as follows: public static <E extends Comparable<E>> void parallel MergeSort(E list) In the main) method, create an array of integers, print the array of integers, then use the parallelMergeSort() on the array, and print the sorted array. Then, repeat the steps for an array of strings

Answer 1

import java.util.Random;
import java.util.concurrent.*;

public class GenericParallelMergeSort {
   public static void main(String[] args) {
       int size = 2000;
       Integer[] intArray = new Integer[size];

       for(int i=0; i<size; i++) {
           intArray[i] = (int)(Math.random()*1000);
       }
       System.out.print("Integer Array List: " );
       for (int i = 0; i < size; i++) {
           System.out.print(intArray[i] + ", ");
       }
       System.out.println();
       parallelMergeSort(intArray);
       System.out.print("Sorted Integer Array List: " );
       for (int i = 0; i < size; i++) {
           System.out.print(intArray[i] + ", ");
       }

       System.out.println();
       System.out.println();
       //Generating random strings
       Random rand = new Random();
       String Alphabets = "abcdefghijklmnopqrstuvwxyz";
       String[] strArray = new String[size];
       for(int i = 0; i < strArray.length; i++) {
           String Str1 = "";
           int randStrLen = 5;
           for(int j = 0; j<randStrLen; j++) {
               char c = Alphabets.charAt(rand.nextInt(26));
               Str1 = Str1 + c;
               strArray[i] = Str1;
           }
       }

       //print string array
       System.out.print("Random String Array List: " );
       for (int i = 0; i < size; i++) {
           System.out.print(strArray[i] + ", ");
       }
       System.out.println();
       parallelMergeSort(strArray);
       System.out.print("Sorted String Array List: " );
       for (int i = 0; i < size; i++) {
           System.out.print(strArray[i] + ", ");
       }

   }

   public static <E extends Comparable<E>> void parallelMergeSort(E[] list) {
       RecursiveAction mainTask = new sortTask<E>(list);
       ForkJoinPool pool = new ForkJoinPool();
       pool.invoke(mainTask);
   }

   private static class sortTask <E extends Comparable<E>> extends RecursiveAction {
       private E[] list;
       private int Threshold = 500;
       public sortTask(E[] list) {
           this.list = list;          
       }

       @Override
       protected void compute() {
           if(list.length < Threshold) {
               java.util.Arrays.sort(list);
           }
           else {
               //obtain the first part
               E[] firstHalf = (E[])(new Comparable[list.length/2]);
               System.arraycopy(list, 0, firstHalf, 0, list.length/2);

               //obtain the second half
               int secondHalfLength = list.length - list.length/2;
               E[] secondHalf = (E[])(new Comparable[secondHalfLength]);
               System.arraycopy(list, list.length/2, secondHalf, 0, secondHalfLength);

               //Recursively sort the two halves
               invokeAll(new sortTask(firstHalf), new sortTask(secondHalf));

               //Merge first half with second half into list

               merge(firstHalf, secondHalf, list);
           }

       }
       public static <E extends Comparable<E>> void merge(E[] list1, E[] list2, E[] temp) {
           int current1 = 0; // Current index in list1
           int current2 = 0; // Current index in list2
           int current3 = 0; // Current index in temp

           while (current1 < list1.length && current2 < list2.length) {
               if (list1[current1].compareTo(list2[current2]) < 0 )
                   temp[current3++] = list1[current1++];
               else
                   temp[current3++] = list2[current2++];
           }

           while (current1 < list1.length)
               temp[current3++] = list1[current1++];

           while (current2 < list2.length)
               temp[current3++] = list2[current2++];
       }

   }
}

Problems <terminated Generic ParallelMergeSort [Java Application] C:\Program Files\Javaljre18.0 201bin\javaw.exe (Jun 6, 2019, 1259-56 AM) Javadoc Declaration Console 655, 449, 495, 644, 617, 208, 944, 373, 293, 862, 148, 792, 890, 93, 854, 358, Sorted Integer Array List: e, e, e, e, e, e, 1, 2, 2, 3, 4, 5, 5, 5, 6, 7, 7, 8, 8, 9, 9, 10, 10, 12, 12, 13, 14, 15, 16, 17, 17, 17, 18, 18, 18, 18, 18, 18, 19, 19, 19, 20, 21, 21 Random String Array List: shavi, mmlgz, qsyej, mlmds, ivkzv, jmwfe, jtrnx, gtumy, fxptk, squan, susjn, hnulf, vejbc, rufim, cyrho, bcjwf, peitu, iggxc, lovdm, dkuft, tlpcj, hbupb, ikb, abwn: abynz, acmcf, acpag, acsrr, String Array aaaim, aaisz, aakh: bekf, abhgo, ablo cvh. dltl, adrho adwws, aegkn, aentu, aetzp, afdpy, Sort aatnm, aawes,