// 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.*; import static onjava.ArrayShow.*; 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 = new CompType[12]; Arrays.setAll(a, n -> CompType.get()); show("Before sorting", a); Arrays.sort(a, new CompTypeComparator()); show("After sorting", a); } } /* Output: Before sorting: [[i = 35, j = 37], [i = 41, j = 20], [i = 77, j = 79] , [i = 56, j = 68], [i = 48, j = 93], [i = 70, j = 7] , [i = 0, j = 25], [i = 62, j = 34], [i = 50, j = 82] , [i = 31, j = 67], [i = 66, j = 54], [i = 21, j = 6] ] After sorting: [[i = 21, j = 6], [i = 70, j = 7], [i = 41, j = 20] , [i = 0, j = 25], [i = 62, j = 34], [i = 35, j = 37] , [i = 66, j = 54], [i = 31, j = 67], [i = 56, j = 68] , [i = 77, j = 79], [i = 50, j = 82], [i = 48, j = 93] ] */