1/* 2 * Copyright (c) 2011, 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 * @bug 8003280 27 * @summary Add lambda tests 28 * Test method reference with SAM interface Comparator<T> 29 * @compile MethodRef5.java 30 * @run main MethodRef5 31 */ 32 33import java.util.Collections; 34import java.util.List; 35import java.util.ArrayList; 36 37public class MethodRef5 { 38 39 static class Person { 40 41 private String firstName; 42 private String lastName; 43 private int age; 44 45 public Person() { } 46 47 public Person(String fn, String ln, int a) { 48 firstName = fn; 49 lastName = ln; 50 age = a; 51 } 52 53 public String getLastName() { 54 return lastName; 55 } 56 57 public int getAge() { 58 return age; 59 } 60 61 //the following 2 methods are signature-compatible with Comparator<Person>.compare(): 62 public static int compareByAge(Person a, Person b) { 63 return a.age - b.age; 64 } 65 66 public int compareByLastName(Person a, Person b) { 67 return a.lastName.compareToIgnoreCase(b.lastName); 68 } 69 } 70 71 private static void assertTrue(boolean cond) { 72 if (!cond) 73 throw new AssertionError(); 74 } 75 76 public static void main(String[] args) { 77 78 List<Person> persons = new ArrayList<Person>(); 79 persons.add(new Person("John", "Smith", 49)); 80 persons.add(new Person("Abraham", "Lincoln", 30)); 81 persons.add(new Person("George", "Washington", 29)); 82 persons.add(new Person("Peter", "Derby", 50)); 83 Collections.sort(persons, Person::compareByAge);//static method reference to compareByAge(Person, Person) 84 String age = ""; 85 for (Person p : persons) { 86 age += p.getAge() + " "; 87 } 88 assertTrue( (age.equals("29 30 49 50 ")) ); 89 Collections.sort(persons, new Person()::compareByLastName);//instance method reference to compareByLastName(Person, Person) 90 String lastName = ""; 91 for (Person p : persons) { 92 lastName += p.getLastName() + " "; 93 } 94 assertTrue( lastName.equals("Derby Lincoln Smith Washington ") ); 95 } 96} 97