File	Doc	Category	Size	Date	Package
Instrumentation.java	API Doc	Java SE 5 API	7969	Fri Aug 26 14:57:06 BST 2005	java.lang.instrument

Instrumentation

Fields Summary

Constructors Summary

Methods Summary
public void	addTransformer(java.lang.instrument.ClassFileTransformer transformer) Registers the supplied transformer. All future class definitions will be seen by the transformer, except definitions of classes upon which any registered transformer is dependent. If multiple transformers are registered, they will be called in the order added. If a transformer throws during execution, the JVM will still call the other registered transformers in order. The same transformer may be added more than once. All transformers registered with addTransformer will always see the class files before any external JVMTI ClassFileLoadHook event listener does. This method is intended for use in instrumentation, as described in the {@linkplain Instrumentation class specification}. param transformer the transformer to register throws java.lang.NullPointerException if passed a null transformer
public java.lang.Class[]	getAllLoadedClasses() Returns an array of all classes currently loaded by the JVM. return an array containing all the classes loaded by the JVM, zero-length if there are none
public java.lang.Class[]	getInitiatedClasses(java.lang.ClassLoader loader) Returns an array of all classes for which loader is an initiating loader. If the supplied loader is null, classes initiated by the bootstrap class loader are returned. param loader the loader whose initiated class list will be returned return an array containing all the classes for which loader is an initiating loader, zero-length if there are none
public long	getObjectSize(java.lang.Object objectToSize) Returns an implementation-specific approximation of the amount of storage consumed by the specified object. The result may include some or all of the object's overhead, and thus is useful for comparison within an implementation but not between implementations. The estimate may change during a single invocation of the JVM. param objectToSize the object to size return an implementation-specific approximation of the amount of storage consumed by the specified object throws java.lang.NullPointerException if the supplied Object is null.
public boolean	isRedefineClassesSupported() Returns whether or not the current JVM configuration supports redefinition of classes. The ability to redefine an already loaded class is an optional capability of a JVM. During a single instantiation of a single JVM, multiple calls to this method will always return the same answer. return true if the current JVM configuration supports redefinition of classes, false if not. see #redefineClasses
public void	redefineClasses(java.lang.instrument.ClassDefinition[] definitions) Redefine the supplied set of classes using the supplied class files. Operates on a set in order to allow interlocked changes to more than one class at the same time (a redefinition of class A can require a redefinition of class B). If a redefined method has active stack frames, those active frames continue to run the bytecodes of the original method. The redefined method will be used on new invokes. This method does not cause any initialization except that which would occur under the customary JVM semantics. In other words, redefining a class does not cause its initializers to be run. The values of static variables will remain as they were prior to the call. Instances of the redefined class are not affected. Registered transformers will be called before the redefine operation is applied. The redefinition may change method bodies, the constant pool and attributes. The redefinition must not add, remove or rename fields or methods, change the signatures of methods, or change inheritance. These restrictions maybe be lifted in future versions. A zero-length definitions array is allowed, in this case, this method does nothing. If this method throws an exception, no classes have been redefined. This method is intended for use in instrumentation, as described in the {@linkplain Instrumentation class specification}. param definitions array of classes to redefine with corresponding definitions throws java.lang.ClassNotFoundException if a specified class cannot be found throws java.lang.instrument.UnmodifiableClassException if a specified class cannot be modified throws java.lang.UnsupportedOperationException if the current configuration of the JVM does not allow redefinition ({@link #isRedefineClassesSupported} is false) or the redefinition made unsupported changes throws java.lang.ClassFormatError if the data did not contain a valid class throws java.lang.NoClassDefFoundError if the name in the class file is not equal to the name of the class throws java.lang.UnsupportedClassVersionError if the class file version numbers are not supported throws java.lang.ClassCircularityError if the new classes contain a circularity throws java.lang.LinkageError if a linkage error occurs throws java.lang.NullPointerException if the supplied definitions array or any of its components is null. see #isRedefineClassesSupported see #addTransformer see java.lang.instrument.ClassFileTransformer
public boolean	removeTransformer(java.lang.instrument.ClassFileTransformer transformer) Unregisters the supplied transformer. Future class definitions will not be shown to the transformer. Removes the most-recently-added matching instance of the transformer. Due to the multi-threaded nature of class loading, it is possible for a transformer to receive calls after it has been removed. Transformers should be written defensively to expect this situation. param transformer the transformer to unregister return true if the transformer was found and removed, false if the transformer was not found throws java.lang.NullPointerException if passed a null transformer