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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22 */
24 /**
25 * @test
26 * @bug 8003280
27 * @summary Add lambda tests
28 * This test is for identifying SAM types #5 and instantiating non-SAM types #7 through inner class,
29 see Helper.java for SAM types
30 * @compile LambdaTest2_SAM3.java Helper.java
31 * @run main LambdaTest2_SAM3
32 */
34 import java.util.Collection;
35 import java.util.List;
36 import java.util.ArrayList;
38 public class LambdaTest2_SAM3 {
39 private static List<String> strs = new ArrayList<String>();
40 private static List<Integer> integers = new ArrayList<Integer>();
42 public static void main(String[] args) {
43 LambdaTest2_SAM3 test = new LambdaTest2_SAM3();
45 //type #7, Not SAM-convertible, through inner class only:
46 test.methodFooBar(new FooBar() {
47 public int getAge(Number n) {
48 System.out.println("getAge(Number n) called");
49 return 100;
50 }
51 public int getAge(Integer i) {
52 System.out.println("getAge(Integer i) called");
53 return 200;
54 }
55 }
56 );
58 //type #7:
59 test.methodDE(new DE(){
60 public int getOldest(List<Integer > list) {
61 System.out.println("getOldest(List<Integer> list) called");
62 return 100;
63 }
64 public int getOldest(Collection<?> collection) {
65 System.out.println("getOldest(Collection<?> collection) called");
66 return 200;
67 }
68 }
69 );
71 }
73 //type #7: Not SAM type
74 void methodFooBar(FooBar fb) {
75 System.out.println("methodFooBar(): interface FooBar object instantiated: " + fb);
76 System.out.println("result=" + fb.getAge(new Byte("10")));
77 System.out.println("result=" + fb.getAge(new Integer(10)));
78 }
80 //type #7: Not SAM type
81 void methodDE (DE de) {
82 System.out.println("methodDE(): interface DE object instantiated: " + de);
83 System.out.println(de.getOldest(integers));
84 System.out.println(de.getOldest(strs));
85 }
86 }