java.lang.Object | ||
↳ | android.app.Fragment | |
↳ | android.app.ListFragment |
A fragment that displays a list of items by binding to a data source such as an array or Cursor, and exposes event handlers when the user selects an item.
ListFragment hosts a ListView
object that can
be bound to different data sources, typically either an array or a Cursor
holding query results. Binding, screen layout, and row layout are discussed
in the following sections.
Screen Layout
ListFragment has a default layout that consists of a single list view.
However, if you desire, you can customize the fragment layout by returning
your own view hierarchy from onCreateView(LayoutInflater, ViewGroup, Bundle)
.
To do this, your view hierarchy must contain a ListView object with the
id "@android:id/list" (or list
if it's in code)
Optionally, your view hierarchy can contain another view object of any type to display when the list view is empty. This "empty list" notifier must have an id "android:empty". Note that when an empty view is present, the list view will be hidden when there is no data to display.
The following code demonstrates an (ugly) custom list layout. It has a list with a green background, and an alternate red "no data" message.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="8dp" android:paddingRight="8dp"> <ListView android:id="@id/android:list" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#00FF00" android:layout_weight="1" android:drawSelectorOnTop="false"/> <TextView android:id="@id/android:empty" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FF0000" android:text="No data"/> </LinearLayout>
Row Layout
You can specify the layout of individual rows in the list. You do this by specifying a layout resource in the ListAdapter object hosted by the fragment (the ListAdapter binds the ListView to the data; more on this later).
A ListAdapter constructor takes a parameter that specifies a layout resource for each row. It also has two additional parameters that let you specify which data field to associate with which object in the row layout resource. These two parameters are typically parallel arrays.
Android provides some standard row layout resources. These are in the
R.layout
class, and have names such as simple_list_item_1,
simple_list_item_2, and two_line_list_item. The following layout XML is the
source for the resource two_line_list_item, which displays two data
fields,one above the other, for each list row.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:id="@+id/text1" android:textSize="16sp" android:textStyle="bold" android:layout_width="match_parent" android:layout_height="wrap_content"/> <TextView android:id="@+id/text2" android:textSize="16sp" android:layout_width="match_parent" android:layout_height="wrap_content"/> </LinearLayout>
You must identify the data bound to each TextView object in this layout. The syntax for this is discussed in the next section.
Binding to Data
You bind the ListFragment's ListView object to data using a class that
implements the ListAdapter
interface.
Android provides two standard list adapters:
SimpleAdapter
for static data (Maps),
and SimpleCursorAdapter
for Cursor
query results.
You must use
ListFragment.setListAdapter()
to
associate the list with an adapter. Do not directly call
ListView.setAdapter()
or else
important initialization will be skipped.
[Expand]
Inherited Constants | |||||||||||
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From interface
android.content.ComponentCallbacks2
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Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Get the ListAdapter associated with this activity's ListView.
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Get the activity's list view widget.
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Get the cursor row ID of the currently selected list item.
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Get the position of the currently selected list item.
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Provide default implementation to return a simple list view.
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Detach from list view.
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This method will be called when an item in the list is selected.
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Attach to list view once the view hierarchy has been created.
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The default content for a ListFragment has a TextView that can
be shown when the list is empty.
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Provide the cursor for the list view.
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Control whether the list is being displayed.
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Like
setListShown(boolean) , but no animation is used when
transitioning from the previous state. | |||||||||||
Set the currently selected list item to the specified
position with the adapter's data
|
[Expand]
Inherited Methods | |||||||||||
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From class
android.app.Fragment
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
android.content.ComponentCallbacks
| |||||||||||
From interface
android.content.ComponentCallbacks2
| |||||||||||
From interface
android.view.View.OnCreateContextMenuListener
|
Get the ListAdapter associated with this activity's ListView.
Get the cursor row ID of the currently selected list item.
Get the position of the currently selected list item.
Provide default implementation to return a simple list view. Subclasses
can override to replace with their own layout. If doing so, the
returned view hierarchy must have a ListView whose id
is android.R.id.list
and can optionally
have a sibling view id android.R.id.empty
that is to be shown when the list is empty.
If you are overriding this method with your own custom content,
consider including the standard layout list_content
in your layout file, so that you continue to retain all of the standard
behavior of ListFragment. In particular, this is currently the only
way to have the built-in indeterminant progress state be shown.
inflater | The LayoutInflater object that can be used to inflate any views in the fragment, |
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container | If non-null, this is the parent view that the fragment's UI should be attached to. The fragment should not add the view itself, but this can be used to generate the LayoutParams of the view. |
savedInstanceState | If non-null, this fragment is being re-constructed from a previous saved state as given here. |
This method will be called when an item in the list is selected. Subclasses should override. Subclasses can call getListView().getItemAtPosition(position) if they need to access the data associated with the selected item.
l | The ListView where the click happened |
---|---|
v | The view that was clicked within the ListView |
position | The position of the view in the list |
id | The row id of the item that was clicked |
Attach to list view once the view hierarchy has been created.
view | The View returned by onCreateView(LayoutInflater, ViewGroup, Bundle) . |
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savedInstanceState | If non-null, this fragment is being re-constructed from a previous saved state as given here. |
The default content for a ListFragment has a TextView that can be shown when the list is empty. If you would like to have it shown, call this method to supply the text it should use.
Provide the cursor for the list view.
Control whether the list is being displayed. You can make it not displayed if you are waiting for the initial data to show in it. During this time an indeterminant progress indicator will be shown instead.
Applications do not normally need to use this themselves. The default
behavior of ListFragment is to start with the list not being shown, only
showing it once an adapter is given with setListAdapter(ListAdapter)
.
If the list at that point had not been shown, when it does get shown
it will be do without the user ever seeing the hidden state.
shown | If true, the list view is shown; if false, the progress indicator. The initial value is true. |
---|
Like setListShown(boolean)
, but no animation is used when
transitioning from the previous state.
Set the currently selected list item to the specified position with the adapter's data