com.vaadin.client.data

Class DataSource.RowHandle<T>

java.lang.Object

com.vaadin.client.data.DataSource.RowHandle<T>

Type Parameters:

T - the row type

Direct Known Subclasses:

AbstractRemoteDataSource.RowHandleImpl

Enclosing interface:

DataSource<T>

public abstract static class DataSource.RowHandle<T>
extends Object

A handle that contains information on whether a row should be pinned or unpinned, and also always the most recent representation for that particular row.

Constructor Summary

Constructors

Constructor and Description
RowHandle()

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
protected abstract boolean	equalsExplicit(Object obj) An explicit override for Object.equals(Object).
abstract T	getRow() Gets the most recent representation for the row this handle represents.
int	hashCode()
protected abstract int	hashCodeExplicit() An explicit override for Object.hashCode().
abstract void	pin() Marks this row as pinned.
abstract void	unpin() Marks this row as unpinned.
abstract void	updateRow() Informs the DataSource that the row data represented by this RowHandle has been updated.

Methods inherited from class java.lang.Object

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

Constructor Detail

RowHandle

public RowHandle()

Method Detail

getRow

public abstract T getRow()
                  throws IllegalStateException

Gets the most recent representation for the row this handle represents.

Returns:

the most recent representation for the row this handle represents

Throws:

IllegalStateException - if this row handle isn't currently pinned

See Also:

pin()

pin

public abstract void pin()

Marks this row as pinned.

Note: Pinning a row multiple times requires an equal amount of unpins to free the row from the "pinned" status.

Technical Note: Pinning a row makes sure that the row object for a particular set of data is always kept as up to date as the data source is able to. Since the DataSource might create a new instance of an object, object references aren't necessarily kept up-to-date. This is a technical work-around for that.

See Also:

unpin()

unpin

public abstract void unpin()
                    throws IllegalStateException

Marks this row as unpinned.

Note: Pinning a row multiple times requires an equal amount of unpins to free the row from the "pinned" status.

Technical Note: Pinning a row makes sure that the row object for a particular set of data is always kept as up to date as the data source is able to. Since the DataSource might create a new instance of an object, object references aren't necessarily kept up-to-date. This is a technical work-around for that.

Throws:

IllegalStateException - if this row handle has not been pinned before

See Also:

pin()

updateRow

public abstract void updateRow()

Informs the DataSource that the row data represented by this RowHandle has been updated. DataChangeHandler for the DataSource should be informed that parts of data have been updated.

See Also:

DataChangeHandler.dataUpdated(int, int)

equalsExplicit

protected abstract boolean equalsExplicit(Object obj)

An explicit override for Object.equals(Object). This method should be functionally equivalent to a properly implemented equals method.

Having a properly implemented equals method is imperative for RowHandle to function. Because Java has no mechanism to force an override of an existing method, we're defining a new method for that instead.

Parameters:

obj - the reference object with which to compare

Returns:

true if this object is the same as the obj argument; false otherwise.

hashCodeExplicit

protected abstract int hashCodeExplicit()

An explicit override for Object.hashCode(). This method should be functionally equivalent to a properly implemented hashCode method.

Having a properly implemented hashCode method is imperative for RowHandle to function. Because Java has no mechanism to force an override of an existing method, we're defining a new method for that instead.

Returns:

a hash code value for this object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object