org.openjdk.jol.info

Class ClassLayout

java.lang.Object

org.openjdk.jol.info.ClassLayout

public class ClassLayout
extends Object

Handles the class data *with* the layout information.

Constructor Summary

Constructors

Constructor and Description
ClassLayout(ClassData classData, SortedSet<FieldLayout> fields, int headerSize, long instanceSize, boolean check) Builds the class layout.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
SortedSet<FieldLayout>	fields() Answer the set of fields, including those in superclasses
int	hashCode()
int	headerSize() Answer header size
long	instanceSize() Answer instance size
static ClassLayout	parseClass(Class<?> klass) Produce the class layout for the given class.
static ClassLayout	parseClass(Class<?> klass, Layouter layouter) Produce the class layout for the given class, and given layouter.
static ClassLayout	parseInstance(Object instance) Produce the class layout for the given instance.
static ClassLayout	parseInstance(Object instance, Layouter layouter) Produce the class layout for the given instance, and given layouter.
String	toPrintable() Produce printable stringly representation of class layout.
String	toPrintable(Object instance) Produce printable stringly representation of class layout.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ClassLayout

public ClassLayout(ClassData classData,
                   SortedSet<FieldLayout> fields,
                   int headerSize,
                   long instanceSize,
                   boolean check)

Builds the class layout.

Parameters:

classData - class data

fields - field layouts

headerSize - header size

instanceSize - instance size

check - whether to check important invariants

Method Detail

parseClass

public static ClassLayout parseClass(Class<?> klass)

Produce the class layout for the given class. This is a shortcut for parseClass(Class,org.openjdk.jol.layouters.Layouter), but with a default layouter.

Parameters:

klass - class to work on

Returns:

class layout

parseClass

public static ClassLayout parseClass(Class<?> klass,
                                     Layouter layouter)

Produce the class layout for the given class, and given layouter. Note: this method is usable as the "caching" shortcut for parseInstance(Object). You can use it to cache the introspection results for a constant-sized objects, e.g. plain Java objects. It is not recommended to use this method on arrays, since their lengths differ from instance to instance.

Parameters:

klass - class to work on

layouter - class layouter

Returns:

class layout

parseInstance

public static ClassLayout parseInstance(Object instance)

Produce the class layout for the given instance. This is a shortcut for parseInstance(java.lang.Object,org.openjdk.jol.layouters.Layouter), but with a default layouter.

Parameters:

instance - instance to work on

Returns:

class layout

parseInstance

public static ClassLayout parseInstance(Object instance,
                                        Layouter layouter)

Produce the class layout for the given instance, and given layouter. These methods, along with parseInstance(Object) are recommended for use when the shape of the object is not known in advance. For example, variable-sized instances (e.g. Java arrays) would not be parsed by parseClass(Class) properly, because their lengths are encoded in the instance objects, not in classes.

Parameters:

instance - instance to work on

layouter - class layouter

Returns:

class layout

fields

public SortedSet<FieldLayout> fields()

Answer the set of fields, including those in superclasses

Returns:

sorted set of fields

instanceSize

public long instanceSize()

Answer instance size

Returns:

instance size

headerSize

public int headerSize()

Answer header size

Returns:

header size

toString

public String toString()

Overrides:

toString in class Object

toPrintable

public String toPrintable()

Produce printable stringly representation of class layout. This method uses the instance originally provided to parseInstance(Object), if that instance is still available.

Returns:

human-readable layout info

toPrintable

public String toPrintable(Object instance)

Produce printable stringly representation of class layout. This method accepts instance to read the actual data from.

Parameters:

instance - instance to work on

Returns:

human-readable layout info

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object