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i'm using eclipse to compile java applet. i have a problem with using reflection to create an instance of class. this problem was introduced in 3.0 M1. code snippet is something like: public Object create(Class type) throws Exception { return type.newInstance(); } i'm using the method from another place like this: create(SomeClass.class) and in some situations this fails with following exception java.lang.IllegalArgumentException: Unresolved java.lang.Class instance (ClassLoader.resolveClass() was not used). at java/lang/Class.newInstance (Class.java) at ...create (...) <--- my create(Class) method "in some situations" means that if SomeClass was loaded before either as a result of resolving some other class, or invoking Class.forName (SomeClass.class.getName()), then exception will not be thrown. i suspect that when compiler see SomeClass.class it produce bytecode that loads class but didn't resolve it that can be good for performance but bad for ms jvm. Sun's plugin does not show this problem.
What JDK level is the MS VM at ?
The class literal isn't supposed to trigger the load of a class. The bytecode sequence we generate uses an array type instead, X.class => Class.forName("[X").getComponentType(); However this feels like a MS VM bug, since newInstance() is spec'ed saying: The class is initialized if it has not already been initialized. You may need to workaround by adding an extra action causing the class to be loaded explicitly, or by creating the class forcing it to be loaded: Instead of using: X.class => Class.forName("[X").getComponentType(); use: Class.forName("X") Other compilers are doing the same as we do (jikes, and javac has committed to change as well).
Ok to close?
my ms jvm is: Microsoft (R) VM for Java, 5.0 Release 5.0.0.3810 this is 1.1.4 (probably higher) in terms of sun's versions.
i compiled the same code with javac and the problem goes away. java -version gives following: Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92) Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode) i agree that it can be just ms jvm bug, but i don't like to change all my code from create(A.class) to create(Class.forName(A.class.getName())) because (1) there are a lot of places i should do it, (2) Class.forName(A.class.getName()) looks ugly. if you give me some hooks to JDT core code where i can investigate this by myself that will okay for me to find it.
Javac hasn't moved yet, though they agreed they should. Jikes has moved, could you give it a try as well ? (version 1.18 or better).
Can't you simply switch to using another VM ?
if all are moving to this, and (i suppose) that change fixes something then we should close it.
Agreed, also see bug 37565 which explains our move, and has a reference to javac bug database.
Reopening to close as duplicate
*** This bug has been marked as a duplicate of 37565 ***
