Tue, 14 May 2013 11:11:09 -0700
8012556: Implement lambda methods on interfaces as static
8006140: Javac NPE compiling Lambda expression on initialization expression of static field in interface
Summary: Lambdas occurring in static contexts or those not needing instance information should be generated into static methods. This has long been the case for classes. However, as a work-around to the lack of support for statics on interfaces, interface lambda methods have been generated into default methods. For lambdas in interface static contexts (fields and static methods) this causes an NPE in javac because there is no 'this'. MethodHandles now support static methods on interfaces. This changeset allows lambda methods to be generated as static interface methods. An existing bug in Hotspot (8013875) is exposed in a test when the "-esa" flag is used. This test and another test that already exposed this bug have been marked with @ignore.
Reviewed-by: mcimadamore
aoqi@0 | 1 | /* |
aoqi@0 | 2 | * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. |
aoqi@0 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
aoqi@0 | 4 | * |
aoqi@0 | 5 | * This code is free software; you can redistribute it and/or modify it |
aoqi@0 | 6 | * under the terms of the GNU General Public License version 2 only, as |
aoqi@0 | 7 | * published by the Free Software Foundation. |
aoqi@0 | 8 | * |
aoqi@0 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
aoqi@0 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
aoqi@0 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
aoqi@0 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
aoqi@0 | 13 | * accompanied this code). |
aoqi@0 | 14 | * |
aoqi@0 | 15 | * You should have received a copy of the GNU General Public License version |
aoqi@0 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
aoqi@0 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
aoqi@0 | 18 | * |
aoqi@0 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
aoqi@0 | 20 | * or visit www.oracle.com if you need additional information or have any |
aoqi@0 | 21 | * questions. |
aoqi@0 | 22 | */ |
aoqi@0 | 23 | |
aoqi@0 | 24 | /** |
aoqi@0 | 25 | * @test |
aoqi@0 | 26 | * @bug 8003280 |
aoqi@0 | 27 | * @summary Add lambda tests |
aoqi@0 | 28 | * This test is for lambda expressions |
aoqi@0 | 29 | * @compile LambdaTest1.java |
aoqi@0 | 30 | * @run main LambdaTest1 |
aoqi@0 | 31 | */ |
aoqi@0 | 32 | |
aoqi@0 | 33 | import java.util.Collections; |
aoqi@0 | 34 | import java.util.List; |
aoqi@0 | 35 | import java.util.ArrayList; |
aoqi@0 | 36 | |
aoqi@0 | 37 | public class LambdaTest1 { |
aoqi@0 | 38 | public static void main(String[] args) { |
aoqi@0 | 39 | |
aoqi@0 | 40 | LambdaTest1 test = new LambdaTest1(); |
aoqi@0 | 41 | |
aoqi@0 | 42 | test.method2((int n) -> { }); |
aoqi@0 | 43 | test.method2((int n) -> { }); |
aoqi@0 | 44 | test.method2((int n) -> { return; }); // ";" is mandatory here |
aoqi@0 | 45 | test.method2((int n) -> { System.out.println(n); }); // ";" is optional here |
aoqi@0 | 46 | test.method2(n -> { System.out.println(n); }); //warning, explict type required for n? |
aoqi@0 | 47 | |
aoqi@0 | 48 | test.method3(()-> { System.out.println("implementing VoidVoid.vvMethod()"); }); |
aoqi@0 | 49 | test.method3(() -> {}); |
aoqi@0 | 50 | |
aoqi@0 | 51 | test.method4(()-> 42); |
aoqi@0 | 52 | test.method4(()-> { return 42; });//";" is mandatory here |
aoqi@0 | 53 | |
aoqi@0 | 54 | test.method5((int n)-> n+1); |
aoqi@0 | 55 | test.method5((int n) -> 42); |
aoqi@0 | 56 | test.method5((int n) -> { return 42; }); |
aoqi@0 | 57 | test.method5( |
aoqi@0 | 58 | (int n) -> { //"{" optional here |
aoqi@0 | 59 | if(n > 0) |
aoqi@0 | 60 | return n++; |
aoqi@0 | 61 | else |
aoqi@0 | 62 | return n--; |
aoqi@0 | 63 | } |
aoqi@0 | 64 | ); |
aoqi@0 | 65 | |
aoqi@0 | 66 | Runnable r = ()-> { System.out.println("Runnable.run() method implemented"); }; |
aoqi@0 | 67 | r.run(); |
aoqi@0 | 68 | ((Runnable)()-> { System.out.println("Runnable.run() method implemented"); }).run(); |
aoqi@0 | 69 | } |
aoqi@0 | 70 | |
aoqi@0 | 71 | void method2(VoidInt a) { |
aoqi@0 | 72 | System.out.println("method2()"); |
aoqi@0 | 73 | final int N = 1; |
aoqi@0 | 74 | int n = 2; //effectively final variable |
aoqi@0 | 75 | System.out.println("method2() \"this\":" + this); |
aoqi@0 | 76 | ((Runnable) |
aoqi@0 | 77 | ()->{ |
aoqi@0 | 78 | System.out.println("inside lambda \"this\":" + this); |
aoqi@0 | 79 | System.out.println("inside lambda accessing final variable N:" + N); |
aoqi@0 | 80 | System.out.println("inside lambda accessing effectively final variable n:" + n); |
aoqi@0 | 81 | } |
aoqi@0 | 82 | ).run(); |
aoqi@0 | 83 | //n++; //compile error if n is modified |
aoqi@0 | 84 | a.viMethod(2); |
aoqi@0 | 85 | } |
aoqi@0 | 86 | |
aoqi@0 | 87 | void method3(VoidVoid a) { |
aoqi@0 | 88 | System.out.println("method3()"); |
aoqi@0 | 89 | a.vvMethod(); |
aoqi@0 | 90 | } |
aoqi@0 | 91 | |
aoqi@0 | 92 | void method4(IntVoid a) { |
aoqi@0 | 93 | System.out.println("method4()"); |
aoqi@0 | 94 | System.out.println(a.ivMethod()); |
aoqi@0 | 95 | } |
aoqi@0 | 96 | |
aoqi@0 | 97 | void method5(IntInt a) { |
aoqi@0 | 98 | System.out.println("method5()"); |
aoqi@0 | 99 | System.out.println(a.iiMethod(5)); |
aoqi@0 | 100 | } |
aoqi@0 | 101 | |
aoqi@0 | 102 | |
aoqi@0 | 103 | //SAM type interfaces |
aoqi@0 | 104 | interface VoidInt { |
aoqi@0 | 105 | void viMethod(int n); |
aoqi@0 | 106 | } |
aoqi@0 | 107 | |
aoqi@0 | 108 | interface VoidVoid { |
aoqi@0 | 109 | void vvMethod(); |
aoqi@0 | 110 | } |
aoqi@0 | 111 | |
aoqi@0 | 112 | interface IntVoid { |
aoqi@0 | 113 | int ivMethod(); |
aoqi@0 | 114 | } |
aoqi@0 | 115 | |
aoqi@0 | 116 | interface IntInt { |
aoqi@0 | 117 | int iiMethod(int n); |
aoqi@0 | 118 | } |
aoqi@0 | 119 | } |