FragmentPagerAdapter
abstract classFragmentPagerAdapter: PagerAdapter
kotlin.Any | ||
↳ | androidx.viewpager.widget.PagerAdapter | |
↳ | androidx.fragment.app.FragmentPagerAdapter |
Implementation of PagerAdapter
that represents each page as a Fragment
that is persistently kept in the fragment manager as long as the user can return to the page.
This version of the pager is best for use when there are a handful of typically more static fragments to be paged through, such as a set of tabs. The fragment of each page the user visits will be kept in memory, though its view hierarchy may be destroyed when not visible. This can result in using a significant amount of memory since fragment instances can hold on to an arbitrary amount of state. For larger sets of pages, consider FragmentStatePagerAdapter
.
When using FragmentPagerAdapter the host ViewPager must have a valid ID set.
Subclasses only need to implement getItem(int)
and getCount()
to have a working adapter.
Here is an example implementation of a pager containing fragments of lists:
The R.layout.fragment_pager
resource of the top-level fragment is:
The R.layout.fragment_pager_list
resource containing each individual fragment's layout is:
Summary
Constants | |
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static Int |
Indicates that only the current fragment will be in the |
static Int |
Indicates that |
Inherited constants | |
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Public constructors | |
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<init>(@NonNull fm: FragmentManager) Constructor for |
|
<init>(@NonNull fm: FragmentManager, behavior: Int) Constructor for |
Public methods | |
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open Unit |
destroyItem(@NonNull container: ViewGroup, position: Int, @NonNull object: Any) |
open Unit |
finishUpdate(@NonNull container: ViewGroup) |
abstract Fragment |
Return the Fragment associated with a specified position. |
open Long |
Return a unique identifier for the item at the given position. |
open Any |
instantiateItem(@NonNull container: ViewGroup, position: Int) |
open Boolean |
isViewFromObject(@NonNull view: View, @NonNull object: Any) |
open Unit |
restoreState(@Nullable state: Parcelable?, @Nullable loader: ClassLoader?) |
open Parcelable? | |
open Unit |
setPrimaryItem(@NonNull container: ViewGroup, position: Int, @NonNull object: Any) |
open Unit |
startUpdate(@NonNull container: ViewGroup) |
Inherited functions | |
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Constants
BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT
static val BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT: Int
Indicates that only the current fragment will be in the Lifecycle.State#RESUMED
state. All other Fragments are capped at Lifecycle.State#STARTED
.
Value: 1
BEHAVIOR_SET_USER_VISIBLE_HINT
static valBEHAVIOR_SET_USER_VISIBLE_HINT: Int
Deprecated: This behavior relies on the deprecated Fragment#setUserVisibleHint(boolean)
API. Use BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT
to switch to its replacement, FragmentTransaction#setMaxLifecycle
.
Indicates that Fragment#setUserVisibleHint(boolean)
will be called when the current fragment changes.
Value: 0
Public constructors
<init>
FragmentPagerAdapter(@NonNull fm: FragmentManager)
Deprecated: use FragmentPagerAdapter(FragmentManager, int)
with BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT
Constructor for FragmentPagerAdapter
that sets the fragment manager for the adapter. This is the equivalent of calling FragmentPagerAdapter(FragmentManager, int)
and passing in BEHAVIOR_SET_USER_VISIBLE_HINT
.
Fragments will have Fragment#setUserVisibleHint(boolean)
called whenever the current Fragment changes.
Parameters | |
---|---|
fm |
FragmentManager: fragment manager that will interact with this adapter |
<init>
FragmentPagerAdapter(
@NonNull fm: FragmentManager,
behavior: Int)
Constructor for FragmentPagerAdapter
. If BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT
is passed in, then only the current Fragment is in the Lifecycle.State#RESUMED
state. All other fragments are capped at Lifecycle.State#STARTED
. If BEHAVIOR_SET_USER_VISIBLE_HINT
is passed, all fragments are in the Lifecycle.State#RESUMED
state and there will be callbacks to Fragment#setUserVisibleHint(boolean)
.
Parameters | |
---|---|
fm |
FragmentManager: fragment manager that will interact with this adapter |
behavior |