OpenJDK 27 · java.beans.DefaultPersistenceDelegate · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private final String[]	constructor
private Boolean	definesEquals
private static final String[]	EMPTY

Access	Constructor and Description
public	DefaultPersistenceDelegate() Creates a persistence delegate for a class with a nullary constructor.
public	DefaultPersistenceDelegate(String[] The property names for the arguments of this constructor. constructorPropertyNames) Creates a default persistence delegate for a class with a constructor whose arguments are the values of the property names as specified by `constructorPropertyNames`.

Method Summary

Modifier and Type	Method and Description
private static boolean	definesEquals(Class<?> type)
private boolean	definesEquals(Object instance)
private void	doProperty(Class<?> type, PropertyDescriptor pd, Object oldInstance, Object newInstance, Encoder out)
private Method	findMethod(Class<?> type, String property)
private static PropertyDescriptor	getPropertyDescriptor(Class<?> type, String property)
private void	initBean(Class<?> type, Object oldInstance, Object newInstance, Encoder out)
protected void	initialize(Class<?> the type of the instances type, Object The instance to be copied. oldInstance, Object The instance that is to be modified. newInstance, Encoder The stream to which any initialization statements should be written. out) Overrides java.beans.PersistenceDelegate.initialize. This default implementation of the `initialize` method assumes all state held in objects of this type is exposed via the matching pairs of "setter" and "getter" methods in the order they are returned by the Introspector.
protected Expression	Returns: An expression whose value is `oldInstance`. instantiate(Object The instance to be instantiated. oldInstance, Encoder The code output stream. out) Implements abstract java.beans.PersistenceDelegate.instantiate. This default implementation of the `instantiate` method returns an expression containing the predefined method name "new" which denotes a call to a constructor with the arguments as specified in the `DefaultPersistenceDelegate`'s constructor.
pack-priv static void	invokeStatement(Object instance, String methodName, Object[] args, Encoder out)
protected boolean	Returns: True if an equivalent copy of `newInstance` may be created by applying a series of mutations to `oldInstance`. mutatesTo(Object The instance to be copied. oldInstance, Object The instance that is to be modified. newInstance) Overrides java.beans.PersistenceDelegate.mutatesTo. If the number of arguments in the specified constructor is non-zero and the class of `oldInstance` explicitly declares an "equals" method this method returns the value of `oldInstance.equals(newInstance)`.

Inherited from java.beans.PersistenceDelegate:: writeObject

Field Detail

constructor	back to summary
private final String[] constructor

definesEquals	back to summary
private Boolean definesEquals

EMPTY	back to summary
private static final String[] EMPTY

Constructor Detail

DefaultPersistenceDelegate back to summary

DefaultPersistenceDelegate	back to summary
public DefaultPersistenceDelegate() Creates a persistence delegate for a class with a nullary constructor. See Also `DefaultPersistenceDelegate(java.lang.String[])`

public DefaultPersistenceDelegate()

Creates a persistence delegate for a class with a nullary constructor.

See Also: DefaultPersistenceDelegate(java.lang.String[])

DefaultPersistenceDelegate back to summary

DefaultPersistenceDelegate	back to summary
public DefaultPersistenceDelegate(String[] constructorPropertyNames) Creates a default persistence delegate for a class with a constructor whose arguments are the values of the property names as specified by `constructorPropertyNames`. The constructor arguments are created by evaluating the property names in the order they are supplied. To use this class to specify a single preferred constructor for use in the serialization of a particular type, we state the names of the properties that make up the constructor's arguments. For example, the `Font` class which does not define a nullary constructor can be handled with the following persistence delegate: new DefaultPersistenceDelegate(new String[]{"name", "style", "size"}); Parameters constructorPropertyNames:String[] The property names for the arguments of this constructor. See Also `instantiate`

public DefaultPersistenceDelegate(String[] constructorPropertyNames)

Creates a default persistence delegate for a class with a constructor whose arguments are the values of the property names as specified by constructorPropertyNames. The constructor arguments are created by evaluating the property names in the order they are supplied. To use this class to specify a single preferred constructor for use in the serialization of a particular type, we state the names of the properties that make up the constructor's arguments. For example, the Font class which does not define a nullary constructor can be handled with the following persistence delegate:

    new DefaultPersistenceDelegate(new String[]{"name", "style", "size"});

Parameters

constructorPropertyNames:String[]: The property names for the arguments of this constructor.

See Also

instantiate

Method Detail

definesEquals	back to summary
private static boolean definesEquals(Class<?> type)

definesEquals	back to summary
private boolean definesEquals(Object instance)

doProperty	back to summary
private void doProperty(Class<?> type, PropertyDescriptor pd, Object oldInstance, Object newInstance, Encoder out) throws Exception

findMethod	back to summary
private Method findMethod(Class<?> type, String property)

getPropertyDescriptor	back to summary
private static PropertyDescriptor getPropertyDescriptor(Class<?> type, String property)

initBean	back to summary
private void initBean(Class<?> type, Object oldInstance, Object newInstance, Encoder out)

initialize back to summary

initialize	back to summary
protected void initialize(Class<?> type, Object oldInstance, Object newInstance, Encoder out) Overrides java.beans.PersistenceDelegate.initialize. This default implementation of the `initialize` method assumes all state held in objects of this type is exposed via the matching pairs of "setter" and "getter" methods in the order they are returned by the Introspector. If a property descriptor defines a "transient" attribute with a value equal to `Boolean.TRUE` the property is ignored by this default implementation. Note that this use of the word "transient" is quite independent of the field modifier that is used by the `ObjectOutputStream`. For each non-transient property, an expression is created in which the nullary "getter" method is applied to the `oldInstance`. The value of this expression is the value of the property in the instance that is being serialized. If the value of this expression in the cloned environment `mutatesTo` the target value, the new value is initialized to make it equivalent to the old value. In this case, because the property value has not changed there is no need to call the corresponding "setter" method and no statement is emitted. If not however, the expression for this value is replaced with another expression (normally a constructor) and the corresponding "setter" method is called to install the new property value in the object. This scheme removes default information from the output produced by streams using this delegate. In passing these statements to the output stream, where they will be executed, side effects are made to the `newInstance`. In most cases this allows the problem of properties whose values depend on each other to actually help the serialization process by making the number of statements that need to be written to the output smaller. In general, the problem of handling interdependent properties is reduced to that of finding an order for the properties in a class such that no property value depends on the value of a subsequent property. Parameters type:Class<?> the type of the instances oldInstance:Object The instance to be copied. newInstance:Object The instance that is to be modified. out:Encoder The stream to which any initialization statements should be written. Annotations @Override Exceptions NullPointerException: if `out` is `null` See Also `java.beans.Introspector#getBeanInfo`, `java.beans.PropertyDescriptor`

protected void initialize(Class<?> type, Object oldInstance, Object newInstance, Encoder out)

Overrides java.beans.PersistenceDelegate.initialize.

This default implementation of the initialize method assumes all state held in objects of this type is exposed via the matching pairs of "setter" and "getter" methods in the order they are returned by the Introspector. If a property descriptor defines a "transient" attribute with a value equal to Boolean.TRUE the property is ignored by this default implementation. Note that this use of the word "transient" is quite independent of the field modifier that is used by the ObjectOutputStream.

For each non-transient property, an expression is created in which the nullary "getter" method is applied to the oldInstance. The value of this expression is the value of the property in the instance that is being serialized. If the value of this expression in the cloned environment mutatesTo the target value, the new value is initialized to make it equivalent to the old value. In this case, because the property value has not changed there is no need to call the corresponding "setter" method and no statement is emitted. If not however, the expression for this value is replaced with another expression (normally a constructor) and the corresponding "setter" method is called to install the new property value in the object. This scheme removes default information from the output produced by streams using this delegate.

In passing these statements to the output stream, where they will be executed, side effects are made to the newInstance. In most cases this allows the problem of properties whose values depend on each other to actually help the serialization process by making the number of statements that need to be written to the output smaller. In general, the problem of handling interdependent properties is reduced to that of finding an order for the properties in a class such that no property value depends on the value of a subsequent property.

Parameters

type:Class<?>: the type of the instances
oldInstance:Object: The instance to be copied.
newInstance:Object: The instance that is to be modified.
out:Encoder: The stream to which any initialization statements should be written.

Annotations

@Override

Exceptions

NullPointerException:: if out is null

instantiate back to summary

instantiate	back to summary
protected Expression instantiate(Object oldInstance, Encoder out) Implements abstract java.beans.PersistenceDelegate.instantiate. This default implementation of the `instantiate` method returns an expression containing the predefined method name "new" which denotes a call to a constructor with the arguments as specified in the `DefaultPersistenceDelegate`'s constructor. Parameters oldInstance:Object The instance to be instantiated. out:Encoder The code output stream. Returns:Expression An expression whose value is `oldInstance`. Annotations @Override Exceptions NullPointerException: if `out` is `null` and this value is used in the method See Also `DefaultPersistenceDelegate(String[])`

protected Expression instantiate(Object oldInstance, Encoder out)

Implements abstract java.beans.PersistenceDelegate.instantiate.

This default implementation of the instantiate method returns an expression containing the predefined method name "new" which denotes a call to a constructor with the arguments as specified in the DefaultPersistenceDelegate's constructor.

Parameters

oldInstance:Object: The instance to be instantiated.
out:Encoder: The code output stream.

Returns:Expression

An expression whose value is oldInstance.

Annotations

@Override

Exceptions

NullPointerException:: if out is null and this value is used in the method

See Also

DefaultPersistenceDelegate(String[])

invokeStatement	back to summary
pack-priv static void invokeStatement(Object instance, String methodName, Object[] args, Encoder out)

mutatesTo back to summary

mutatesTo	back to summary
protected boolean mutatesTo(Object oldInstance, Object newInstance) Overrides java.beans.PersistenceDelegate.mutatesTo. If the number of arguments in the specified constructor is non-zero and the class of `oldInstance` explicitly declares an "equals" method this method returns the value of `oldInstance.equals(newInstance)`. Otherwise, this method uses the superclass's definition which returns true if the classes of the two instances are equal. Parameters oldInstance:Object The instance to be copied. newInstance:Object The instance that is to be modified. Returns:boolean True if an equivalent copy of `newInstance` may be created by applying a series of mutations to `oldInstance`. Annotations @Override See Also `DefaultPersistenceDelegate(String[])`

protected boolean mutatesTo(Object oldInstance, Object newInstance)

Overrides java.beans.PersistenceDelegate.mutatesTo.

If the number of arguments in the specified constructor is non-zero and the class of oldInstance explicitly declares an "equals" method this method returns the value of oldInstance.equals(newInstance). Otherwise, this method uses the superclass's definition which returns true if the classes of the two instances are equal.

Parameters

oldInstance:Object: The instance to be copied.
newInstance:Object: The instance that is to be modified.

Returns:boolean

True if an equivalent copy of newInstance may be created by applying a series of mutations to oldInstance.

Annotations

@Override

See Also

DefaultPersistenceDelegate(String[])

public Class DefaultPersistenceDelegate

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