// arrays/ComparatorTest.java // (c)2016 MindView LLC: see Copyright.txt // We make no guarantees that this code is fit for any purpose. // Visit http://mindviewinc.com/Books/OnJava/ for more book information. // Implementing a Comparator for a class. import java.util.*; import onjava.*; class CompTypeComparator implements Comparator { public int compare(CompType o1, CompType o2) { return (o1.j < o2.j ? -1 : (o1.j == o2.j ? 0 : 1)); } } public class ComparatorTest { public static void main(String[] args) { CompType[] a = Generated.array( new CompType[12], CompType.generator()); System.out.println("before sorting:"); System.out.println(Arrays.toString(a)); Arrays.sort(a, new CompTypeComparator()); System.out.println("after sorting:"); System.out.println(Arrays.toString(a)); } } /* Output: before sorting: [[i = 58, j = 55], [i = 93, j = 61], [i = 61, j = 29] , [i = 68, j = 0], [i = 22, j = 7], [i = 88, j = 28] , [i = 51, j = 89], [i = 9, j = 78], [i = 98, j = 61] , [i = 20, j = 58], [i = 16, j = 40], [i = 11, j = 22] ] after sorting: [[i = 68, j = 0], [i = 22, j = 7], [i = 11, j = 22] , [i = 88, j = 28], [i = 61, j = 29], [i = 16, j = 40] , [i = 58, j = 55], [i = 20, j = 58], [i = 93, j = 61] , [i = 98, j = 61], [i = 9, j = 78], [i = 51, j = 89] ] */