universum.studios.android.pager.adapter

Class FragmentPagerAdapter

java.lang.Object

PagerAdapter

universum.studios.android.pager.adapter.FragmentPagerAdapter

Direct Known Subclasses:

BaseFragmentPagerAdapter

public abstract class FragmentPagerAdapter
extends PagerAdapter

A PagerAdapter implementation that represents each page as a Fragment that is persistently kept in the fragment manager as long as a user can return to the page.

This version of the pager adapter 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.

Note, that when using FragmentPagerAdapter, the host ViewPager must have a valid ID set, otherwise this adapter implementation will throw an exception.

The inheritance hierarchies only need to implement getItem(int) and #getCount() to become a fully working adapters.

Constructor Summary

Constructors

Constructor and Description
FragmentPagerAdapter(FragmentManager fragmentManager) Creates a new instance of FragmentPagerAdapter with the specified fragmentManager.

Method Summary

Modifier and Type	Method and Description
void	destroyItem(ViewGroup container, int position, Object object)
void	finishUpdate(ViewGroup container)
abstract Fragment	getItem(int position) Instantiates a new Fragment associated with the specified position.
long	getItemId(int position) Returns a unique identifier for the item at the specified position.
Fragment	getPrimaryFragment() Returns the fragment instance that has been set as primary item via setPrimaryItem(ViewGroup, int, Object).
int	getPrimaryPosition() Returns position of the current primary item.
Object	instantiateItem(ViewGroup container, int position)
boolean	isViewFromObject(View view, Object object)
protected String	makeItemTag(int containerId, long itemId) Makes a tag for an item with the given itemId.
protected void	setMakeItemTags(boolean makeItemTags) Sets a boolean flag indicating whether this pager adapter should make tags for its items or not.
void	setPrimaryItem(ViewGroup container, int position, Object object)
void	startUpdate(ViewGroup container)

Methods inherited from class java.lang.Object

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

Constructor Detail

FragmentPagerAdapter

public FragmentPagerAdapter(@NonNull
                            FragmentManager fragmentManager)

Creates a new instance of FragmentPagerAdapter with the specified fragmentManager.

Parameters:

fragmentManager - The manager used to manage fragments provided by the pager adapter.

Method Detail

startUpdate

public void startUpdate(ViewGroup container)

instantiateItem

public Object instantiateItem(ViewGroup container,
                              int position)

setMakeItemTags

protected final void setMakeItemTags(boolean makeItemTags)

Sets a boolean flag indicating whether this pager adapter should make tags for its items or not.

This feature is by default enabled.

Parameters:

makeItemTags - True to enable making of item tags, false otherwise.

See Also:

makeItemTag(int, long)

makeItemTag

@Nullable
protected String makeItemTag(@IdRes
                                        int containerId,
                                        long itemId)

Makes a tag for an item with the given itemId.

By default making of item tags is enabled and the default implementation makes tag in the following format:

 "android:pager:CONTAINER_ID:ITEM_ID"
 

This feature may be enabled/disabled via setMakeItemTags(boolean).

Parameters:

containerId - Id of the associated view pager container.

itemId - Id of the item for which to create its corresponding tag.

Returns:

Item's tag or null if this adapter does not create tags for its items.

getItemId

public long getItemId(int position)

Returns a unique identifier for the item at the specified position.

The default implementation returns the given position. The inheritance hierarchies should override this method if the positions of items can change.

Parameters:

position - Position from the range of size of this this adapter.

Returns:

Unique identifier for the item at the requested position.

getItem

@NonNull
public abstract Fragment getItem(int position)

Instantiates a new Fragment associated with the specified position.

See Also:

instantiateItem(ViewGroup, int)

setPrimaryItem

public void setPrimaryItem(ViewGroup container,
                           int position,
                           Object object)

getPrimaryFragment

@Nullable
public Fragment getPrimaryFragment()

Returns the fragment instance that has been set as primary item via setPrimaryItem(ViewGroup, int, Object).

Returns:

Currently primary fragment. May be null if no primary item has been set yet.

See Also:

getPrimaryPosition()

getPrimaryPosition

public int getPrimaryPosition()

Returns position of the current primary item.

Returns:

Primary item's position or -1 if no primary item has been specified yet.

See Also:

getPrimaryFragment(), setPrimaryItem(ViewGroup, int, Object)

isViewFromObject

public boolean isViewFromObject(View view,
                                Object object)

destroyItem

public void destroyItem(ViewGroup container,
                        int position,
                        Object object)

finishUpdate

public void finishUpdate(ViewGroup container)