1 /*
   2  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /**
  25  * @test
  26  * @summary Comparator API narrowing type test
  27  * @run testng TypeTest
  28  */
  29 
  30 import java.util.function.Function;
  31 import java.util.Map;
  32 import java.util.TreeMap;
  33 import java.util.Comparator;
  34 import org.testng.annotations.Test;
  35 
  36 @Test(groups = "unit")
  37 public class TypeTest {
  38     static class Person {
  39         String name;
  40         static Comparator<Person> C = (p1, p2) -> p1.name.compareTo(p2.name);
  41 
  42         Person(String name) {
  43             this.name = name;
  44         }
  45 
  46         String getName() { return name; }
  47     }
  48 
  49     static class Employee extends Person {
  50         int id;
  51         static Comparator<Employee> C = (e1, e2) -> e1.id - e2.id;
  52 
  53         Employee(int id, String name) {
  54             super(name);
  55             this.id = id;
  56         }
  57     }
  58 
  59     static class Manager extends Employee {
  60         long reports;
  61         static Comparator<Manager> C = (e1, e2) -> (int) (e1.reports - e2.reports);
  62 
  63         Manager(String name, int id, long reports) {
  64             super(id, name);
  65             this.reports = reports;
  66         }
  67     }
  68 
  69     static <T> void assertOrder(T o1, T o2, Comparator<? super T> cmp) {
  70         if (cmp.compare(o1, o2) > 0) {
  71             System.out.println("Fail!!");
  72         }
  73         if (cmp.compare(o1, o2) == 0) {
  74             System.out.println("Equal!!");
  75         }
  76     }
  77 
  78     public static void main(String[] args) {
  79         Manager m1 = new Manager("Manager", 2, 2000);
  80         Manager m2 = new Manager("Manager", 4, 1300);
  81 
  82         // Comparator<Employee> tmp = Person.C;
  83 
  84         // Comparator<Manager> cmp = Employee.C.thenComparing(Person.C);
  85         Comparator<Employee> cmp = Employee.C.thenComparing(Person.C);
  86         assertOrder(m1, m2, Employee.C.thenComparing(Person.C));
  87         assertOrder(m1, m2, cmp);
  88         assertOrder(m1, new Employee(1, "Z"), Person.C);
  89         assertOrder(new Employee(1, "Z"), m2, Employee.C);
  90 
  91         assertOrder(m1, m2, Comparator.comparing(Employee::getName, String.CASE_INSENSITIVE_ORDER));
  92 
  93         Map<String, Integer> map = new TreeMap<>();
  94         map.entrySet().stream().sorted(Map.Entry.comparingByKey(String.CASE_INSENSITIVE_ORDER));
  95     }
  96 }