java.lang.instrument

Interface Instrumentation

public interface Instrumentation

An Instrumentation object has transformers that will be called each time a class is defined or redefined. The object is given to a premain function that is called before the main function.

Since:

1.5

Method Summary

Methods

Modifier and Type	Method and Description
void	addTransformer(ClassFileTransformer transformer) Adds a ClassFileTransformer object to the instrumentation.
java.lang.Class[]	getAllLoadedClasses() Get all the classes loaded by the JVM.
java.lang.Class[]	getInitiatedClasses(java.lang.ClassLoader loader) Get all the classes loaded by a given class loader
long	getObjectSize(java.lang.Object objectToSize) Get the size of an object.
boolean	isRedefineClassesSupported() Returns if the current JVM supports class redefinition
void	redefineClasses(ClassDefinition[] definitions) Redefine classes present in the definitions array, with the corresponding class files.
boolean	removeTransformer(ClassFileTransformer transformer) Removes the given transformer from the set of transformers this Instrumentation object has.

Method Detail

addTransformer

void addTransformer(ClassFileTransformer transformer)

Adds a ClassFileTransformer object to the instrumentation. Each time a class is defined or redefined, the transform method of the transformer object is called.

Parameters:

transformer - the transformer to add

Throws:

java.lang.NullPointerException - if transformer is null

removeTransformer

boolean removeTransformer(ClassFileTransformer transformer)

Removes the given transformer from the set of transformers this Instrumentation object has.

Parameters:

transformer - the transformer to remove

Returns:

true if the transformer was found and removed, false if the transformer was not found

Throws:

java.lang.NullPointerException - if transformer is null

isRedefineClassesSupported

boolean isRedefineClassesSupported()

Returns if the current JVM supports class redefinition

Returns:

true if the current JVM supports class redefinition

redefineClasses

void redefineClasses(ClassDefinition[] definitions)
                     throws java.lang.ClassNotFoundException,
                            UnmodifiableClassException

Redefine classes present in the definitions array, with the corresponding class files.

Parameters:

definitions - an array of classes to redefine

Throws:

java.lang.ClassNotFoundException - if a class cannot be found

UnmodifiableClassException - if a class cannot be modified

java.lang.UnsupportedOperationException - if the JVM does not support redefinition or the redefinition made unsupported changes

java.lang.ClassFormatError - if a class file is not valid

java.lang.NoClassDefFoundError - if a class name is not equal to the name in the class file specified

java.lang.UnsupportedClassVersionError - if the class file version numbers are unsupported

java.lang.ClassCircularityError - if circularity occured with the new classes

java.lang.LinkageError - if a linkage error occurs

java.lang.NullPointerException - if the definitions array is null, or any of its element

See Also:

isRedefineClassesSupported(), addTransformer(java.lang.instrument.ClassFileTransformer), ClassFileTransformer

getAllLoadedClasses

java.lang.Class[] getAllLoadedClasses()

Get all the classes loaded by the JVM.

Returns:

an array containing all the classes loaded by the JVM. The array is empty if no class is loaded.

getInitiatedClasses

java.lang.Class[] getInitiatedClasses(java.lang.ClassLoader loader)

Get all the classes loaded by a given class loader

Parameters:

loader - the loader

Returns:

an array containing all the classes loaded by the given loader. The array is empty if no class was loaded by the loader.

getObjectSize

long getObjectSize(java.lang.Object objectToSize)

Get the size of an object. It contains the size of all fields.

Parameters:

objectToSize - the object

Returns:

the size of the object

Throws:

java.lang.NullPointerException - if objectToSize is null.