public
class
SortedList
extends Object
java.lang.Object | |
↳ | android.support.v7.util.SortedList<T> |
A Sorted list implementation that can keep items in order and also notify for changes in the
list
such that it can be bound to a RecyclerView.Adapter
.
It keeps items ordered using the compare(Object, Object)
method and uses
binary search to retrieve items. If the sorting criteria of your items may change, make sure you
call appropriate methods while editing them to avoid data inconsistencies.
You can control the order of items and change notifications via the SortedList.Callback
parameter.
Nested classes | |
---|---|
class |
SortedList.BatchedCallback<T2>
A callback implementation that can batch notify events dispatched by the SortedList. |
class |
SortedList.Callback<T2>
The class that controls the behavior of the |
Constants | |
---|---|
int |
INVALID_POSITION
Used by |
Public constructors | |
---|---|
SortedList(Class<T> klass, Callback<T> callback)
Creates a new SortedList of type T. |
|
SortedList(Class<T> klass, Callback<T> callback, int initialCapacity)
Creates a new SortedList of type T. |
Public methods | |
---|---|
int
|
add(T item)
Adds the given item to the list. |
void
|
addAll(T... items)
Adds the given items to the list. |
void
|
addAll(Collection<T> items)
Adds the given items to the list. |
void
|
addAll(T[] items, boolean mayModifyInput)
Adds the given items to the list. |
void
|
beginBatchedUpdates()
Batches adapter updates that happen between calling this method until calling
|
void
|
clear()
Removes all items from the SortedList. |
void
|
endBatchedUpdates()
Ends the update transaction and dispatches any remaining event to the callback. |
T
|
get(int index)
Returns the item at the given index. |
int
|
indexOf(T item)
Returns the position of the provided item. |
void
|
recalculatePositionOfItemAt(int index)
This method can be used to recalculate the position of the item at the given index, without
triggering an |
boolean
|
remove(T item)
Removes the provided item from the list and calls |
T
|
removeItemAt(int index)
Removes the item at the given index and calls |
int
|
size()
The number of items in the list. |
void
|
updateItemAt(int index, T item)
Updates the item at the given index and calls |
Inherited methods | |
---|---|
From
class
java.lang.Object
|
int INVALID_POSITION
Used by indexOf(Object)
when he item cannot be found in the list.
Constant Value: -1 (0xffffffff)
SortedList (Class<T> klass, Callback<T> callback)
Creates a new SortedList of type T.
Parameters | |
---|---|
klass |
Class :
The class of the contents of the SortedList. |
callback |
Callback :
The callback that controls the behavior of SortedList.
|
SortedList (Class<T> klass, Callback<T> callback, int initialCapacity)
Creates a new SortedList of type T.
Parameters | |
---|---|
klass |
Class :
The class of the contents of the SortedList. |
callback |
Callback :
The callback that controls the behavior of SortedList. |
initialCapacity |
int :
The initial capacity to hold items.
|
int add (T item)
Adds the given item to the list. If this is a new item, SortedList calls
onInserted(int, int)
.
If the item already exists in the list and its sorting criteria is not changed, it is
replaced with the existing Item. SortedList uses
areItemsTheSame(Object, Object)
to check if two items are the same item
and uses areContentsTheSame(Object, Object)
to decide whether it should
call onChanged(int, int)
or not. In both cases, it always removes the
reference to the old item and puts the new item into the backing array even if
areContentsTheSame(Object, Object)
returns false.
If the sorting criteria of the item is changed, SortedList won't be able to find
its duplicate in the list which will result in having a duplicate of the Item in the list.
If you need to update sorting criteria of an item that already exists in the list,
use updateItemAt(int, Object)
. You can find the index of the item using
indexOf(Object)
before you update the object.
Parameters | |
---|---|
item |
T :
The item to be added into the list. |
Returns | |
---|---|
int |
The index of the newly added item. |
void addAll (T... items)
Adds the given items to the list. Does not modify the input.
Parameters | |
---|---|
items |
T :
Array of items to be added into the list.
|
void addAll (Collection<T> items)
Adds the given items to the list. Does not modify the input.
Parameters | |
---|---|
items |
Collection :
Collection of items to be added into the list.
|
void addAll (T[] items, boolean mayModifyInput)
Adds the given items to the list. Equivalent to calling add(T)
in a loop,
except the callback events may be in a different order/granularity since addAll can batch
them for better performance.
If allowed, may modify the input array and even take the ownership over it in order to avoid extra memory allocation during sorting and deduplication.
Parameters | |
---|---|
items |
T :
Array of items to be added into the list. |
mayModifyInput |
boolean :
If true, SortedList is allowed to modify the input. |
void beginBatchedUpdates ()
Batches adapter updates that happen between calling this method until calling
endBatchedUpdates()
. For example, if you add multiple items in a loop
and they are placed into consecutive indices, SortedList calls
onInserted(int, int)
only once with the proper item count. If an event
cannot be merged with the previous event, the previous event is dispatched
to the callback instantly.
After running your data updates, you must call endBatchedUpdates()
which will dispatch any deferred data change event to the current callback.
A sample implementation may look like this:
mSortedList.beginBatchedUpdates(); try { mSortedList.add(item1) mSortedList.add(item2) mSortedList.remove(item3) ... } finally { mSortedList.endBatchedUpdates(); }
Instead of using this method to batch calls, you can use a Callback that extends
SortedList.BatchedCallback
. In that case, you must make sure that you are manually calling
dispatchLastEvent()
right after you complete your data changes.
Failing to do so may create data inconsistencies with the Callback.
If the current Callback in an instance of SortedList.BatchedCallback
, calling this method
has no effect.
void clear ()
Removes all items from the SortedList.
void endBatchedUpdates ()
Ends the update transaction and dispatches any remaining event to the callback.
T get (int index)
Returns the item at the given index.
Parameters | |
---|---|
index |
int :
The index of the item to retrieve. |
Returns | |
---|---|
T |
The item at the given index. |
Throws | |
---|---|
IndexOutOfBoundsException |
if provided index is negative or larger than the size of the list. |
int indexOf (T item)
Returns the position of the provided item.
Parameters | |
---|---|
item |
T :
The item to query for position. |
Returns | |
---|---|
int |
The position of the provided item or INVALID_POSITION if item is not in the
list.
|
void recalculatePositionOfItemAt (int index)
This method can be used to recalculate the position of the item at the given index, without
triggering an onChanged(int, int)
callback.
If you are editing objects in the list such that their position in the list may change but
you don't want to trigger an onChange animation, you can use this method to re-position it.
If the item changes position, SortedList will call onMoved(int, int)
without
calling onChanged(int, int)
.
A sample usage may look like:
final int position = mSortedList.indexOf(item); item.incrementPriority(); // assume items are sorted by priority mSortedList.recalculatePositionOfItemAt(position);In the example above, because the sorting criteria of the item has been changed, mSortedList.indexOf(item) will not be able to find the item. This is why the code above first gets the position before editing the item, edits it and informs the SortedList that item should be repositioned.
Parameters | |
---|---|
index |
int :
The current index of the Item whose position should be re-calculated. |
See also:
boolean remove (T item)
Removes the provided item from the list and calls onRemoved(int, int)
.
Parameters | |
---|---|
item |
T :
The item to be removed from the list. |
Returns | |
---|---|
boolean |
True if item is removed, false if item cannot be found in the list. |
T removeItemAt (int index)
Removes the item at the given index and calls onRemoved(int, int)
.
Parameters | |
---|---|
index |
int :
The index of the item to be removed. |
Returns | |
---|---|
T |
The removed item. |
int size ()
The number of items in the list.
Returns | |
---|---|
int |
The number of items in the list. |
void updateItemAt (int index, T item)
Updates the item at the given index and calls onChanged(int, int)
and/or
onMoved(int, int)
if necessary.
You can use this method if you need to change an existing Item such that its position in the list may change.
If the new object is a different object (get(index) != item
) and
areContentsTheSame(Object, Object)
returns true
, SortedList
avoids calling onChanged(int, int)
otherwise it calls
onChanged(int, int)
.
If the new position of the item is different than the provided index
,
SortedList
calls onMoved(int, int)
.
Parameters | |
---|---|
index |
int :
The index of the item to replace |
item |
T :
The item to replace the item at the given Index. |
See also: