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
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8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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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 *
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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22 */
24 /**
25 * @test
26 * @bug 8003280
27 * @summary Add lambda tests
28 * This test is for generic methods whose type is the same as the type
29 of the generic SAM interface that is taken as the parameter of the
30 generic method; the type can be inferred from the value of the other
31 type arguments
32 * @compile InferenceTest4.java
33 * @run main InferenceTest4
34 */
36 import java.util.List;
37 import java.util.ArrayList;
39 public class InferenceTest4 {
41 private static void assertTrue(boolean b) {
42 if(!b)
43 throw new AssertionError();
44 }
46 public static void main(String[] args) {
47 InferenceTest4 test = new InferenceTest4();
48 test.method1(n -> n.size(), "abc", "java.lang.String");
49 test.method1(n -> n.size(), 'c', "java.lang.Character");
50 test.method1(n -> n.size(), 0, "java.lang.Integer");
51 test.method1(n -> n.size(), 0.1, "java.lang.Double");
52 test.method1(n -> n.size(), 0.1f, "java.lang.Float");
53 test.method1(n -> n.size(), 0L, "java.lang.Long");
54 test.method1(n -> n.size(), (short)0, "java.lang.Short");
55 test.method1(n -> n.size(), (byte)0, "java.lang.Byte");
56 test.method1(n -> n.size(), true, "java.lang.Boolean");
57 test.method1(n -> n.size(), new int[]{1, 2, 3}, "[I");
58 test.method1(n -> n.size(), new double[]{1.0}, "[D");
59 test.method1(n -> n.size(), new String[]{}, "[Ljava.lang.String;");
60 }
62 <T> void method1(SAM1<T> s, T t, String className) {
63 List<T> list = new ArrayList<T>();
64 System.out.println(className + "-" + t.getClass().getName());
65 assertTrue(t.getClass().getName().equals(className));
66 list.add(t);
67 assertTrue(s.m1(list) == 1);
68 }
70 interface SAM1<T> {
71 int m1(List<T> x);
72 }
73 }