[ann] IDEA-69688 (unrestricted cast of return types of JSR-292 "polymorphic" methods)

2026-08-26 03:13:40 +07:00 · 2011-05-18 17:14:14 +04:00
parent fad296984a
commit a66489593b
5 changed files with 112 additions and 3 deletions
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2000-2011 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+
+class C {
+  // from http://download.java.net/jdk7/docs/api/java/lang/invoke/MethodHandle.html, "Usage examples"
+  void m() throws Throwable {
+    Object x, y; String s; int i;
+    MethodType mt; MethodHandle mh;
+    MethodHandles.Lookup lookup = MethodHandles.lookup();
+
+// mt is (char,char)String
+    mt = MethodType.methodType(String.class, char.class, char.class);
+    mh = lookup.findVirtual(String.class, "replace", mt);
+    s = (String) mh.invokeExact("daddy",'d','n');
+
+// invokeExact(Ljava/lang/String;CC)Ljava/lang/String;
+    assert(s.equals("nanny"));
+
+// weakly typed invocation (using MHs.invoke)
+    s = (String) mh.invokeWithArguments("sappy", 'p', 'v');
+    assert(s.equals("savvy"));
+
+// mt is (Object[])List
+    mt = MethodType.methodType(java.util.List.class, Object[].class);
+    mh = lookup.findStatic(java.util.Arrays.class, "asList", mt);
+    assert(mh.isVarargsCollector());
+    x = mh.invokeGeneric("one", "two");
+
+// invokeGeneric(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
+    assert(x.equals(java.util.Arrays.asList("one","two")));
+
+// mt is (Object,Object,Object)Object
+    mt = MethodType.genericMethodType(3);
+    mh = mh.asType(mt);
+    x = mh.invokeExact((Object)1, (Object)2, (Object)3);
+
+// invokeExact(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
+    assert(x.equals(java.util.Arrays.asList(1,2,3)));
+
+// mt is int()
+    mt = MethodType.methodType(int.class);
+    mh = lookup.findVirtual(java.util.List.class, "size", mt);
+    i = (int) mh.invokeExact(java.util.Arrays.asList(1,2,3));
+
+// invokeExact(Ljava/util/List;)I
+    assert(i == 3);
+    mt = MethodType.methodType(void.class, String.class);
+    mh = lookup.findVirtual(java.io.PrintStream.class, "println", mt);
+    mh.invokeExact(System.out, "Hello, world.");
+// invokeExact(Ljava/io/PrintStream;Ljava/lang/String;)V
+  }
+
+  void unsupported() {
+    Object o = 42;
+    int i = <error descr="Inconvertible types; cannot cast 'java.lang.Object' to 'int'">(int) o</error>;
+    System.out.println(i);
+    m(<error descr="Inconvertible types; cannot cast 'java.lang.Object' to 'int'">(int) o</error>);
+    if (<error descr="Inconvertible types; cannot cast 'java.lang.Object' to 'int'">o instanceof int</error>) {
+      i = (Integer) o;
+      System.out.println(i);
+    }
+  }
+
+  void m(int i) { }
+}