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
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 */
24 import java.util.*;
26 /**
27 * @test
28 * @bug 8003280
29 * @summary Add lambda tests
30 * Parameter types inferred from target type in generics with wildcard
31 * @compile InferenceTest2b.java
32 * @run main InferenceTest2b
33 */
35 public class InferenceTest2b {
37 private static void assertTrue(boolean cond) {
38 if (!cond)
39 throw new AssertionError();
40 }
42 public static void main(String[] args) {
44 InferenceTest2b test = new InferenceTest2b();
46 test.m1((a, b) -> {return a;});
47 test.m2((a, b) -> {return a;});
48 test.m3((a, b) -> a);
49 }
51 interface SAM6<T> {
52 T m6(T a, T b);
53 }
55 void m1(SAM6<? super List<?>> s) {
56 System.out.println("m1()");
57 Stack<String> a = new Stack<String>();
58 ArrayList<String> b = new ArrayList<String>();
59 assertTrue(s.m6(a, b) == a);
61 Vector<?> c = null;
62 assertTrue(s.m6(c, b) == c);
63 }
65 void m2(SAM6<? super Integer> s) {
66 System.out.println("m2()");
67 assertTrue(s.m6(1, 2) == 1);
68 }
70 void m3(SAM6<? super Calendar> s) {
71 System.out.println("m3()");
72 Calendar gc = Calendar.getInstance();
73 GregorianCalendar gc2 = new GregorianCalendar();
74 assertTrue(s.m6(gc, gc2) == gc);
75 }
76 }