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 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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
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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 self referential and recursive lambda expression that have type inference
29 * @compile InferenceTest11.java
30 * @run main InferenceTest11
31 */
33 public class InferenceTest11 {
35 private static void assertTrue(boolean b) {
36 if(!b)
37 throw new AssertionError();
38 }
40 static Func<Integer, Integer> f1;
41 static Func<Integer, ? extends Number> f2;
43 public static void main(String[] args) {
45 f1 = n -> {
46 if(n <= 0)
47 return 0;
48 if(n == 1)
49 return 1;
50 return f1.m(n-1) + f1.m(n-2);
51 };
52 assertTrue(f1.m(-1) == 0);
53 assertTrue(f1.m(0) == 0);
54 assertTrue(f1.m(10) == 55);
56 f2 = n -> {
57 if(n <= 1)
58 return 1.0;
59 return 2 * (Double)f2.m(n-1) + 1;
60 };
61 assertTrue(f2.m(4).doubleValue() == 15.0);
62 }
64 interface Func<T, V> {
65 V m(T t);
66 }
67 }