Module openj9.dtfj

Package com.ibm.dtfj.java.j9

Class JavaAbstractClass

java.lang.Object

com.ibm.dtfj.java.j9.JavaAbstractClass

All Implemented Interfaces:

JavaClass

Direct Known Subclasses:

JavaArrayClass, JavaClass

public abstract class JavaAbstractClass
extends Object
implements JavaClass

Field Summary

Fields

Modifier and Type	Field	Description
protected ImagePointer	_classPointer
protected JavaRuntime	_javaVM

Fields declared in interface com.ibm.dtfj.java.JavaClass

MODIFIERS_UNAVAILABLE

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	JavaAbstractClass(JavaRuntime vm, ImagePointer id, int modifiers, long loaderID, ImagePointer objectID, int flagOffset, int hashcodeSlot)

Method Summary

Modifier and Type	Method	Description
protected void	addClassLoaderReference(Collection coll)
protected void	addClassObjectReference(Collection coll)
void	addInterfaceName(String interfaceName)
protected void	addSuperclassReference(Collection coll)
boolean	equals(Object obj)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
JavaClassLoader	getClassLoader()	Fetch the class loader associated with this class.
int	getHashcodeSlotSize()	Returns the size of the extra slot needed for stored hashcode - if the object was moved - in JVMs built with J9VM_OPT_NEW_OBJECT_HASH.
ImagePointer	getID()	The ID of a class is a pointer to a section of memory which identifies the class.
abstract int	getInstanceSize(JavaObject instance)
Iterator	getInterfaces()	Get the set of names of interfaces directly implemented by this class.
int	getModifiers()	Return the Java language modifiers for this class.
JavaObject	getObject()	Fetch the java.lang.Class object associated with this class.
JavaObject	getProtectionDomain()	Returns the protection domain for this class.
int	hashCode()	Answers an integer hash code for the receiver.
int	readFlagsFromInstance(JavaObject instance)

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods declared in interface com.ibm.dtfj.java.JavaClass

getComponentType, getConstantPoolReferences, getDeclaredFields, getDeclaredMethods, getInstanceSize, getName, getReferences, getSuperclass, isArray

Field Details

_classPointer

protected ImagePointer _classPointer

_javaVM

protected JavaRuntime _javaVM

Constructor Details

JavaAbstractClass

protected JavaAbstractClass(JavaRuntime vm,
 ImagePointer id,
 int modifiers,
 long loaderID,
 ImagePointer objectID,
 int flagOffset,
 int hashcodeSlot)

Method Details

getClassLoader

public JavaClassLoader getClassLoader()
                               throws CorruptDataException

Description copied from interface: JavaClass

Fetch the class loader associated with this class. Classes defined in the bootstrap class loader (including classes representing primitive types or void) will always return a JavaClassLoader representing the bootstrap class loader. This asymmetry with java.lang.Class#getClassLoader() is intentional.

Specified by:

getClassLoader in interface JavaClass

Returns:

the JavaClassLoader in which this class was defined

Throws:

CorruptDataException - if the class loader for this class cannot be found (a class cannot exist without a loader so this implies corruption)

getObject

public JavaObject getObject()
                     throws CorruptDataException

Description copied from interface: JavaClass

Fetch the java.lang.Class object associated with this class.

In some implementations this may be null if no object has been created to represent this class, or if the class is synthetic.

Specified by:

getObject in interface JavaClass

Returns:

the java.lang.Class object associated with this class

Throws:

CorruptDataException

See Also:

• JavaClass.getID()

getModifiers

public int getModifiers()
                 throws CorruptDataException

Description copied from interface: JavaClass

Return the Java language modifiers for this class.

The modifiers are defined by the JVM Specification.

Return MODIFIERS_UNAVAILABLE if the modifiers are unavailable. This might be the case if DTFJ is operating against an artefact such as a portable heap dump that does not contain information about a class's modifiers.

Note that, for inner classes, the actual modifiers are returned, not the synthetic modifiers. For instance, a class will never have its 'protected' modifier set, even if the inner class was a protected member, since 'protected' is not a legal modifier for a class file.

Specified by:

getModifiers in interface JavaClass

Returns:

the modifiers for this class

Throws:

CorruptDataException

getID

public ImagePointer getID()

Description copied from interface: JavaClass

The ID of a class is a pointer to a section of memory which identifies the class. The contents of this memory are implementation defined.

In some implementations getID() and getObject().getID() may return the same value. This implies that the class object is also the primary internal representation of the class. DTFJ users should not rely on this behaviour.

In some implementations, getID() may return null for some classes. This indicates that the class is a synthetic class which has been constructed for DTFJ purposes only. The class has no physical representation in the VM.

Specified by:

getID in interface JavaClass

Returns:

a pointer to the class

getInterfaces

public Iterator getInterfaces()

Description copied from interface: JavaClass

Get the set of names of interfaces directly implemented by this class.

Specified by:

getInterfaces in interface JavaClass

Returns:

an iterator over the collection of the names of interfaces directly implemented by this class. Some JVM implementations may choose to load interfaces lazily, so only the names are returned. The JavaClass objects may be found through the defining class loader.

See Also:

• String
• JavaClassLoader.findClass(String)
• CorruptData

addInterfaceName

public void addInterfaceName(String interfaceName)

getInstanceSize

public abstract int getInstanceSize(JavaObject instance)

Parameters:

instance - The instance is needed for array types to calculate the size of a per-instance basis

Returns:

The size, in bytes, of an instance of this class (required for iterating the heap)

equals

public boolean equals(Object obj)

Description copied from class: java.lang.Object

Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison. The implementation in Object answers true only if the argument is the exact same object as the receiver (==).

Specified by:

equals in interface JavaClass

Overrides:

equals in class Object

Parameters:

obj -

Returns:

True if the given object refers to the same Java Class in the image

See Also:

• Object.hashCode()

getHashcodeSlotSize

public int getHashcodeSlotSize()

Returns the size of the extra slot needed for stored hashcode - if the object was moved - in JVMs built with J9VM_OPT_NEW_OBJECT_HASH. If the hashcode could fit in spare space in the object header, this will return 0. . *

Returns:

object instance size delta, in bytes

hashCode

public int hashCode()

Description copied from class: java.lang.Object

Answers an integer hash code for the receiver. Any two objects which answer true when passed to .equals must answer the same value for this method.

Specified by:

hashCode in interface JavaClass

Overrides:

hashCode in class Object

Returns:

the receiver's hash.

See Also:

• Object.equals(java.lang.Object)

readFlagsFromInstance

public int readFlagsFromInstance(JavaObject instance)
                          throws MemoryAccessException,
CorruptDataException

Throws:

MemoryAccessException

CorruptDataException

addClassLoaderReference

protected void addClassLoaderReference(Collection coll)

addSuperclassReference

protected void addSuperclassReference(Collection coll)

addClassObjectReference

protected void addClassObjectReference(Collection coll)

getProtectionDomain

public JavaObject getProtectionDomain()
                               throws DataUnavailable,
CorruptDataException

Description copied from interface: JavaClass

Returns the protection domain for this class.

Specified by:

getProtectionDomain in interface JavaClass

Returns:

the protection domain or null for the default protection domain

Throws:

DataUnavailable

CorruptDataException