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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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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 * SAM types and method type inference
29 * @author Brian Goetz
30 * @author Maurizio Cimadamore
31 * @run main LambdaConv03
32 */
34 public class LambdaConv03 {
36 static int assertionCount = 0;
38 static void assertTrue(boolean cond) {
39 assertionCount++;
40 if (!cond)
41 throw new AssertionError();
42 }
44 interface TU<T, U> {
45 public T foo(U u);
46 }
48 public static <T, U> T exec(TU<T, U> lambda, U x) {
49 return lambda.foo(x);
50 }
52 static {
53 //Covariant returns:
54 int i1 = exec((Integer x) -> { return x; }, 3);
55 assertTrue(3 == i1);
56 //Method resolution with boxing:
57 int i2 = exec((Integer x) -> { return x; }, 3);
58 assertTrue(3 == i2);
59 //Runtime exception transparency:
60 try {
61 exec((Object x) -> { return x.hashCode(); }, null);
62 }
63 catch (RuntimeException e) {
64 assertTrue(true);
65 }
66 }
68 {
69 //Covariant returns:
70 int i1 = exec((Integer x) -> { return x; }, 3);
71 assertTrue(3 == i1);
72 //Method resolution with boxing:
73 int i2 = exec((Integer x) -> { return x; }, 3);
74 assertTrue(3 == i2);
75 //Runtime exception transparency:
76 try {
77 exec((Object x) -> { return x.hashCode(); }, null);
78 }
79 catch (RuntimeException e) {
80 assertTrue(true);
81 }
82 }
84 public static void test1() {
85 //Covariant returns:
86 int i1 = exec((Integer x) -> { return x; }, 3);
87 assertTrue(3 == i1);
88 //Method resolution with boxing:
89 int i2 = exec((Integer x) -> { return x; }, 3);
90 assertTrue(3 == i2);
91 //Runtime exception transparency:
92 try {
93 exec((Object x) -> { return x.hashCode(); }, null);
94 }
95 catch (RuntimeException e) {
96 assertTrue(true);
97 }
98 }
100 public void test2() {
101 //Covariant returns:
102 int i1 = exec((Integer x) -> { return x; }, 3);
103 assertTrue(3 == i1);
104 //Method resolution with boxing:
105 int i2 = exec((Integer x) -> { return x; }, 3);
106 assertTrue(3 == i2);
107 //Runtime exception transparency:
108 try {
109 exec((Object x) -> { return x.hashCode(); }, null);
110 }
111 catch (RuntimeException e) {
112 assertTrue(true);
113 }
114 }
116 public static void main(String[] args) {
117 test1();
118 new LambdaConv03().test2();
119 assertTrue(assertionCount == 12);
120 }
121 }