/* * 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; @SuppressWarnings({"UnusedDeclaration"}) 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 MethodHandle mh0 = lookup.findVirtual(String.class, "length", MethodType.methodType(int.class)); MethodHandle mh1 = MethodHandles.convertArguments(mh0, MethodType.methodType(Integer.class, String.class)); System.out.println((Integer) mh1.invokeExact("daddy")); } void supported() { Object o = 42; int i = (int) o; String s = ""; int i1 = <error descr="Inconvertible types; cannot cast 'java.lang.String' to 'int'">(int) s</error>; System.out.println(i); m((int) o); } void unsupported() { Object o = 42; if (<error descr="Inconvertible types; cannot cast 'java.lang.Object' to 'int'">o instanceof int</error>) { int i = (Integer) o; System.out.println(i); } } void m(int i) { } void asLongs(Integer i) { long l = (long) i; } void foo(Object o) {} public void cast2(Byte operand) { foo((<warning descr="Casting 'operand' to 'byte' is redundant">byte</warning>)operand); foo((short)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Byte' to 'char'">(char)operand</error>); foo((int)operand); foo((long)operand); foo((float)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Byte' to 'boolean'">(boolean)operand</error>); } public void cast2(Short operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Short' to 'byte'">(byte)operand</error>); foo((<warning descr="Casting 'operand' to 'short' is redundant">short</warning>)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Short' to 'char'">(char)operand</error>); foo((int)operand); foo((long)operand); foo((float)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Short' to 'boolean'">(boolean)operand</error>); } public void cast2(Character operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Character' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Character' to 'short'">(short)operand</error>); foo((<warning descr="Casting 'operand' to 'char' is redundant">char</warning>)operand); foo((int)operand); foo((long)operand); foo((float)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Character' to 'boolean'">(boolean)operand</error>); } public void cast2(Integer operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Integer' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Integer' to 'short'">(short)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Integer' to 'char'">(char)operand</error>); foo((<warning descr="Casting 'operand' to 'int' is redundant">int</warning>)operand); foo((long)operand); foo((float)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Integer' to 'boolean'">(boolean)operand</error>); } public void cast2(Long operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Long' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Long' to 'short'">(short)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Long' to 'char'">(char)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Long' to 'int'">(int)operand</error>); foo((<warning descr="Casting 'operand' to 'long' is redundant">long</warning>)operand); foo((float)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Long' to 'boolean'">(boolean)operand</error>); } public void cast2(Float operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'short'">(short)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'char'">(char)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'int'">(int)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'long'">(long)operand</error>); foo((<warning descr="Casting 'operand' to 'float' is redundant">float</warning>)operand); foo((double)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Float' to 'boolean'">(boolean)operand</error>); } public void cast2(Double operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'short'">(short)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'char'">(char)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'int'">(int)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'long'">(long)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'float'">(float)operand</error>); foo((<warning descr="Casting 'operand' to 'double' is redundant">double</warning>)operand); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Double' to 'boolean'">(boolean)operand</error>); } public void cast2(Boolean operand) { foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'byte'">(byte)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'short'">(short)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'char'">(char)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'int'">(int)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'long'">(long)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'float'">(float)operand</error>); foo(<error descr="Inconvertible types; cannot cast 'java.lang.Boolean' to 'double'">(double)operand</error>); foo((<warning descr="Casting 'operand' to 'boolean' is redundant">boolean</warning>)operand); } public void cast2(Object operand) { foo((<warning descr="Casting 'operand' to 'byte' is redundant">byte</warning>)operand); foo((<warning descr="Casting 'operand' to 'short' is redundant">short</warning>)operand); foo((<warning descr="Casting 'operand' to 'char' is redundant">char</warning>)operand); foo((<warning descr="Casting 'operand' to 'int' is redundant">int</warning>)operand); foo((<warning descr="Casting 'operand' to 'long' is redundant">long</warning>)operand); foo((<warning descr="Casting 'operand' to 'float' is redundant">float</warning>)operand); foo((<warning descr="Casting 'operand' to 'double' is redundant">double</warning>)operand); foo((<warning descr="Casting 'operand' to 'boolean' is redundant">boolean</warning>)operand); } }