io.permazen.change

Class Change<T>

java.lang.Object

io.permazen.change.Change<T>

Type Parameters:

T - the type of the object that changed

Direct Known Subclasses:

FieldChange, ObjectCreate, ObjectDelete

public abstract class Change<T>
extends Object

Object change notification.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Change(T jobj) Constructor.

Method Summary

Modifier and Type	Method and Description
void	apply() Apply this change to the transaction associated with the current thread.
void	apply(JObject jobj) Apply this change to the specified object.
void	apply(JTransaction jtx) Apply this change to the object associated with this instance in the given transaction.
abstract void	apply(JTransaction jtx, JObject jobj) Apply this change to the given object in the given transaction.
boolean	equals(Object obj)
JObject	getJObject() Get the Java model object containing the field that changed.
T	getObject() Get the Java model object containing the field that changed.
int	hashCode()
abstract <R> R	visit(ChangeSwitch<R> target) Apply visitor pattern.

Methods inherited from class java.lang.Object

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

Constructor Detail

Change

protected Change(T jobj)

Constructor.

Parameters:

jobj - Java model object that changed

Throws:

IllegalArgumentException - if jobj is null

Method Detail

getObject

public T getObject()

Get the Java model object containing the field that changed.

Although not declared as such to allow flexibility in Java model types, the returned object will always be a JObject instance.

Returns:

the changed object

getJObject

public JObject getJObject()

Get the Java model object containing the field that changed.

This is a convenience method, equivalent to:

(JObject)getObject()

Returns:

the changed object as a JObject

visit

public abstract <R> R visit(ChangeSwitch<R> target)

Apply visitor pattern. Invokes the method of target corresponding to this instance's type.

Type Parameters:

R - visitor return type

Parameters:

target - visitor pattern target

Returns:

value returned by the selected method of target

apply

public abstract void apply(JTransaction jtx,
                           JObject jobj)

Apply this change to the given object in the given transaction.

Parameters:

jobj - the target object to which to apply this change

jtx - the transaction in which to apply this change

Throws:

NullPointerException - if jtx or jobj is null

DeletedObjectException - if jobj does not exist in jtx

UnknownFieldException - if jobj has a schema version that does not contain the affected field, or in which the affected field has a different type

RuntimeException - if there is some other incompatibility between this change and the target object, for example, setting a list element at an index that is out of bounds

StaleTransactionException - if jtx is no longer usable

apply

public void apply(JTransaction jtx)

Apply this change to the object associated with this instance in the given transaction.

This is a convenience method, equivalent to:

apply(jtx, this.getJObject());

Parameters:

jtx - transaction in which to apply this change

Throws:

IllegalArgumentException - if jtx is null

apply

public void apply()

Apply this change to the transaction associated with the current thread.

This is a convenience method, equivalent to:

apply(JTransaction.getCurrent())

Throws:

IllegalStateException - if there is no JTransaction associated with the current thread

apply

public void apply(JObject jobj)

Apply this change to the specified object.

This is a convenience method, equivalent to:

apply(obj.getTransaction(), jobj);

Parameters:

jobj - object to which to apply this change

Throws:

IllegalStateException - if there is no JTransaction associated with jobj

IllegalArgumentException - if jobj is null

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object