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Sunday, 22 January 2017

Chapter 23 Exercise 1, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

23.1 (Generic bubble sort) Write the following two generic methods using bubble
sort. The first method sorts the elements using the Comparable interface and
the second uses the Comparator interface.

public static <E extends Comparable<E>>
void bubbleSort(E[] list)
public static <E> void bubbleSort(E[] list,
Comparator<? super E> comparator)


import java.util.Comparator;

public class Exercise01 {

 public static void main(String[] args) {
  Integer[] array1 = new Integer[10];
  for (int i = 0; i < array1.length; i++) {
   array1[i] = (int)(Math.random() * 100000);
  }
  System.out.println(java.util.Arrays.toString(array1));
  bubbleSort(array1);
  System.out.println(java.util.Arrays.toString(array1));
  
  Integer[] array2 = new Integer[10];
  for (int i = 0; i < array2.length; i++) {
   array2[i] = (int)(Math.random() * 100000);
  }
  System.out.println("\n\n" + java.util.Arrays.toString(array2));
  bubbleSort(array2, new IntegerComparator());
  System.out.println(java.util.Arrays.toString(array2));
 }
 
 static class IntegerComparator implements Comparator<Integer> {
  @Override
  public int compare(Integer o1, Integer o2) {
   return o1.intValue() - o2.intValue();
  }
  
 }
 
 public static <E extends Comparable<E>> void bubbleSort(E[] list) {
  boolean needNextPass = true;
  for (int k = 1; k < list.length && needNextPass; k++) {
   needNextPass = false;
   for (int i = 0; i < list.length - k; i++) {
    if (list[i].compareTo(list[i + 1]) > 0) {
     E temp = list[i];
     list[i] = list[i + 1];
     list[i + 1] = temp;
     needNextPass = true;
    }
   }
  }
 }
 
 public static <E> void bubbleSort(E[] list, Comparator<? super E> comparator) {
  boolean needNextPass = true;
  for (int k = 1; k < list.length && needNextPass; k++) {
   needNextPass = false;
   for (int i = 0; i < list.length - k; i++) {
    if (comparator.compare(list[i], list[i + 1]) > 0) {
     E temp = list[i];
     list[i] = list[i + 1];
     list[i + 1] = temp;
     needNextPass = true;
    }
   }
  }
 }

}

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