Question

This assignment simply requests that you take the quicksort algorithm that you have been working with and make it generic. You are to demonstrate the effectiveness of your work by defining the main method that passes a list of Integers, Doubles, and Strings and sorts them all.

NOTE: this is the code, please tell me which one of the blocks of code does.

import java.util.*;

public class Driver{

public static <T extends Comparable<T>> void quickSort(T[] data, int a, int b) {

if (a < b) {

int i = a, j = b;

T x = data[(i + j) / 2];

do {

while (data[i].compareTo(x) < 0) i++;

while (x.compareTo(data[j]) < 0) j--;

if ( i <= j) {

T tmp = data[i];

data[i] = data[j];

data[j] = tmp;

i++;

j--;

}

} while (i <= j);

quickSort(data, a, j);

quickSort(data, i, b);

}

}

public static void main(String args[]) {

String[] names = {"John", "Paul", "Anna", "Rock"};

Driver.<String>quickSort(names, 0, names.length-1);

for(String i: names) {

System.out.println(i);

}

}

}

Answer 1

import java.util.*;

public class Driver {
    public static <T extends Comparable<T>> void quickSort(T[] data, int a, int b) {
        if (a < b) {
            int i = a, j = b;
            T x = data[(i + j) / 2];
            do {
                while (data[i].compareTo(x) < 0) i++;
                while (x.compareTo(data[j]) < 0) j--;
                if (i <= j) {
                    T tmp = data[i];
                    data[i] = data[j];
                    data[j] = tmp;
                    i++;
                    j--;
                }
            } while (i <= j);
            quickSort(data, a, j);
            quickSort(data, i, b);
        }
    }

    public static void main(String args[]) {
        String[] names = {"John", "Paul", "Anna", "Rock"};
        Driver.quickSort(names, 0, names.length - 1);
        System.out.println("Strings in sorted order are");
        for (String i : names) {
            System.out.println(i);
        }
        System.out.println();

        Integer[] integers = {4, 0, 1, 2, 9, 5};
        Driver.quickSort(integers, 0, integers.length - 1);
        System.out.println("Integers in sorted order are");
        for (Integer i : integers) {
            System.out.println(i);
        }
        System.out.println();

        Double[] doubles = {9.5, 2.0, 5.6, 8.2, 3.7};
        Driver.quickSort(doubles, 0, doubles.length - 1);
        System.out.println("Doubles in sorted order are");
        for (Double i : doubles) {
            System.out.println(i);
        }
        System.out.println();
    }
}

Strings in sorted order are Anna John Rock Integers in sorted order are Doubles in sorted order are 2. 0 5.6 8.2 9.5