Module openj9.dtfj

Package com.ibm.j9ddr.vm29.view.dtfj.java

Class DTFJJavaClass

java.lang.Object

com.ibm.j9ddr.vm29.view.dtfj.java.DTFJJavaClass

All Implemented Interfaces:

JavaClass

public class DTFJJavaClass
extends Object
implements JavaClass

Field Summary

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

MODIFIERS_UNAVAILABLE

Constructor Summary

Constructors

Constructor	Description
DTFJJavaClass(com.ibm.j9ddr.vm29.pointer.generated.J9ClassPointer j9class)

Method Summary

Modifier and Type	Method	Description
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.
JavaClass	getComponentType()	For array classes, returns a JavaClass representing the component type of this array class.
Iterator	getConstantPoolReferences()	Java classes may refer to other classes and to String objects via the class's constant pool.
Iterator	getDeclaredFields()	Get the set of fields declared in this class.
Iterator	getDeclaredMethods()	Get the set of methods declared in this class.
String	getFilename()
ImagePointer	getID()	The ID of a class is a pointer to a section of memory which identifies the class.
long	getInstanceSize()	Returns the size in bytes of an instance of this class on the heap.
Iterator	getInterfaces()	Get the set of names of interfaces directly implemented by this class.
int	getModifiers()	Return the Java language modifiers for this class.
String	getName()	Get the name of the class.
JavaObject	getObject()	Fetch the java.lang.Class object associated with this class.
long	getPackedDataSize()
JavaObject	getProtectionDomain()	Returns the protection domain for this class.
Iterator	getReferences()	Get the set of references from this class.
JavaClass	getSuperclass()	Get the immediate superclass of this class.
int	hashCode()	Answers an integer hash code for the receiver.
boolean	isArray()	Is this an array class ?
boolean	isPacked()

Methods declared in class java.lang.Object

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

Constructor Details

DTFJJavaClass

public DTFJJavaClass(com.ibm.j9ddr.vm29.pointer.generated.J9ClassPointer j9class)

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)

getComponentType

public JavaClass getComponentType()
                           throws CorruptDataException

Description copied from interface: JavaClass

For array classes, returns a JavaClass representing the component type of this array class.

Specified by:

getComponentType in interface JavaClass

Returns:

a JavaClass representing the component type of this array class

Throws:

CorruptDataException

getConstantPoolReferences

public Iterator getConstantPoolReferences()

Description copied from interface: JavaClass

Java classes may refer to other classes and to String objects via the class's constant pool. These references are followed by the garbage collector, forming edges on the graph of reachable objects. This getConstantPoolReferences() may be used to determine which objects are referred to by the receiver's constant pool.

Although Java VMs typically permit only Class and String objects in the constant pool, some esoteric or future virtual machines may permit other types of objects to occur in the constant pool. This API imposes no restrictions on the types of JavaObjects which might be included in the Iterator.

No assumption should be made about the order in which constant pool references are returned.

Classes may also refer to objects through static variables. These may be found with the getDeclaredFields() API. Objects referenced by static variables are not returned by getConstantPoolReferences() unless the object is also referenced by the constant pool.

Specified by:

getConstantPoolReferences in interface JavaClass

Returns:

an iterator over the collection of JavaObjects which are referred to by the constant pool of this class

See Also:

• JavaObject
• CorruptData

getDeclaredFields

public Iterator getDeclaredFields()

Description copied from interface: JavaClass

Get the set of fields declared in this class.

Specified by:

getDeclaredFields in interface JavaClass

Returns:

an iterator over the collection of fields declared in this class.

See Also:

• JavaField
• CorruptData

getDeclaredMethods

public Iterator getDeclaredMethods()

Description copied from interface: JavaClass

Get the set of methods declared in this class.

Specified by:

getDeclaredMethods in interface JavaClass

Returns:

an iterator over the collection of methods declared in this class.

See Also:

• JavaMethod
• CorruptData

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

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

getName

public String getName()
               throws CorruptDataException

Description copied from interface: JavaClass

Get the name of the class.

Specified by:

getName in interface JavaClass

Returns:

the name of the class in the form: "full/package/class$innerclass"

Throws:

CorruptDataException

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()

getReferences

public Iterator getReferences()

Description copied from interface: JavaClass

Get the set of references from this class.

Specified by:

getReferences in interface JavaClass

Returns:

an iterator of JavaReferences

See Also:

• JavaReference
• CorruptData

getSuperclass

public JavaClass getSuperclass()
                        throws CorruptDataException

Description copied from interface: JavaClass

Get the immediate superclass of this class.

Specified by:

getSuperclass in interface JavaClass

Returns:

the immediate superclass of this class, or null if this class has no superclass. For interfaces, Object, primitive types and void null is always returned.

Throws:

CorruptDataException

isArray

public boolean isArray()
                throws CorruptDataException

Description copied from interface: JavaClass

Is this an array class ?

Specified by:

isArray in interface JavaClass

Returns:

true if this class is an array class

Throws:

CorruptDataException

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()

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)

getFilename

public String getFilename()
                   throws CorruptDataException

Throws:

CorruptDataException

getInstanceSize

public long getInstanceSize()
                     throws CorruptDataException

Description copied from interface: JavaClass

Returns the size in bytes of an instance of this class on the heap.

The call is only meaningful for a non-array JavaClass, where all instances of the class are of the same size. If this method is called on a JavaArrayClass, where instances can be of different sizes, an UnsupportedOperationException will be thrown. DataUnavailable can be thrown if no value is available: for example when DTFJ is examining a javacore, where the instance size for a class is not recorded.

Specified by:

getInstanceSize in interface JavaClass

Returns:

size in bytes of an instance

Throws:

CorruptDataException

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

isPacked

public boolean isPacked()

getPackedDataSize

public long getPackedDataSize()
                       throws DataUnavailable,
CorruptDataException

Throws:

DataUnavailable

CorruptDataException