Add ability to scroll to top by tab click at the Account activity (#1146)

* Issue: tuskyapp#1078
Add ability to scroll to top by tab click at the Account activity

* Fix issue with scroll tabs other than current

* Update scroll on click behavior

* Update code formatting

* Remove unused code

* Move tab click listener from Fragments to Activities

app/src/main/java/com/keylesspalace/tusky/AccountActivity.kt

@@ -41,12 +41,14 @@ import com.google.android.material.appbar.AppBarLayout
 import com.google.android.material.appbar.CollapsingToolbarLayout
 import com.google.android.material.floatingactionbutton.FloatingActionButton
 import com.google.android.material.snackbar.Snackbar
+import com.google.android.material.tabs.TabLayout
 import com.keylesspalace.tusky.adapter.AccountFieldAdapter
 import com.keylesspalace.tusky.di.ViewModelFactory
 import com.keylesspalace.tusky.entity.Account
 import com.keylesspalace.tusky.entity.Relationship
 import com.keylesspalace.tusky.interfaces.ActionButtonActivity
 import com.keylesspalace.tusky.interfaces.LinkListener
+import com.keylesspalace.tusky.interfaces.ReselectableFragment
 import com.keylesspalace.tusky.pager.AccountPagerAdapter
 import com.keylesspalace.tusky.util.*
 import com.keylesspalace.tusky.viewmodel.AccountViewModel
@@ -104,6 +106,8 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
         REQUESTED
     }
 
+    private var adapter: AccountPagerAdapter? = null
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -174,7 +178,8 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
 
         // Add a listener to change the toolbar icon color when it enters/exits its collapsed state.
         accountAppBarLayout.addOnOffsetChangedListener(object : AppBarLayout.OnOffsetChangedListener {
-            @AttrRes var priorAttribute = R.attr.account_toolbar_icon_tint_uncollapsed
+            @AttrRes
+            var priorAttribute = R.attr.account_toolbar_icon_tint_uncollapsed
 
             override fun onOffsetChanged(appBarLayout: AppBarLayout, verticalOffset: Int) {
 
@@ -250,9 +255,9 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
         accountFieldList.adapter = accountFieldAdapter
 
         // Setup the tabs and timeline pager.
-        val adapter = AccountPagerAdapter(supportFragmentManager, accountId)
+        adapter = AccountPagerAdapter(supportFragmentManager, accountId)
         val pageTitles = arrayOf(getString(R.string.title_statuses), getString(R.string.title_statuses_with_replies), getString(R.string.title_statuses_pinned), getString(R.string.title_media))
-        adapter.setPageTitles(pageTitles)
+        adapter?.setPageTitles(pageTitles)
         accountFragmentViewPager.pageMargin = resources.getDimensionPixelSize(R.dimen.tab_page_margin)
         val pageMarginDrawable = ThemeUtils.getDrawable(this, R.attr.tab_page_margin_drawable,
                 R.drawable.tab_page_margin_dark)
@@ -260,10 +265,21 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
         accountFragmentViewPager.adapter = adapter
         accountFragmentViewPager.offscreenPageLimit = 2
         accountTabLayout.setupWithViewPager(accountFragmentViewPager)
+        accountTabLayout.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
+            override fun onTabReselected(tab: TabLayout.Tab?) {
+                tab?.position?.let {
+                    (adapter?.getFragment(tab.position) as? ReselectableFragment)?.onReselect()
+                }
+            }
 
+            override fun onTabUnselected(tab: TabLayout.Tab?) {}
+
+            override fun onTabSelected(tab: TabLayout.Tab?) {}
+
+        })
         val accountListClickListener = { v: View ->
             val type = when (v.id) {
-                R.id.accountFollowers-> AccountListActivity.Type.FOLLOWERS
+                R.id.accountFollowers -> AccountListActivity.Type.FOLLOWERS
                 R.id.accountFollowing -> AccountListActivity.Type.FOLLOWS
                 else -> throw AssertionError()
             }
@@ -424,7 +440,7 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
     }
 
     private fun updateFollowButton() {
-        if(isSelf) {
+        if (isSelf) {
             accountFollowButton.setText(R.string.action_edit_own_profile)
             return
         }
@@ -449,7 +465,7 @@ class AccountActivity : BottomSheetActivity(), ActionButtonActivity, HasSupportF
             accountFollowButton.show()
             updateFollowButton()
 
-            if(isSelf) {
+            if (isSelf) {
                 accountFloatingActionButton.hide()
             } else {
                 accountFloatingActionButton.show()

app/src/main/java/com/keylesspalace/tusky/MainActivity.java

@@ -16,20 +16,25 @@
 package com.keylesspalace.tusky;
 
 import androidx.lifecycle.Lifecycle;
+
 import android.content.Intent;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.Bundle;
+
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
 import com.google.android.material.tabs.TabLayout;
+
 import androidx.emoji.text.EmojiCompat;
 import androidx.fragment.app.Fragment;
 import androidx.core.content.ContextCompat;
 import androidx.viewpager.widget.ViewPager;
 import androidx.appcompat.app.AlertDialog;
+
 import android.os.Handler;
 import android.util.Log;
 import android.view.KeyEvent;
@@ -44,6 +49,7 @@ import com.keylesspalace.tusky.components.conversation.ConversationsRepository;
 import com.keylesspalace.tusky.db.AccountEntity;
 import com.keylesspalace.tusky.entity.Account;
 import com.keylesspalace.tusky.interfaces.ActionButtonActivity;
+import com.keylesspalace.tusky.interfaces.ReselectableFragment;
 import com.keylesspalace.tusky.pager.MainPagerAdapter;
 import com.keylesspalace.tusky.util.CustomEmojiHelper;
 import com.keylesspalace.tusky.util.NotificationHelper;
@@ -114,12 +120,13 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
     private ViewPager viewPager;
 
     private int notificationTabPosition;
+    private MainPagerAdapter adapter;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        if(accountManager.getActiveAccount() == null) {
+        if (accountManager.getActiveAccount() == null) {
             // will be redirected to LoginActivity by BaseActivity
             return;
         }
@@ -209,6 +216,12 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
 
             @Override
             public void onTabReselected(TabLayout.Tab tab) {
+                if (adapter != null) {
+                    Fragment fragment = adapter.getFragment(tab.getPosition());
+                    if (fragment instanceof ReselectableFragment) {
+                        ((ReselectableFragment) fragment).onReselect();
+                    }
+                }
             }
         });
 
@@ -410,7 +423,7 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
     private void setupTabs(boolean selectNotificationTab) {
         List<TabData> tabs = accountManager.getActiveAccount().getTabPreferences();
 
-        MainPagerAdapter adapter = new MainPagerAdapter(tabs, getSupportFragmentManager());
+        adapter = new MainPagerAdapter(tabs, getSupportFragmentManager());
         viewPager.setAdapter(adapter);
 
         tabLayout.setupWithViewPager(viewPager);
@@ -420,9 +433,9 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
                     .setIcon(tabs.get(i).getIcon())
                     .setContentDescription(tabs.get(i).getText());
             tabLayout.addTab(tab);
-            if(tabs.get(i).getId().equals(TabDataKt.NOTIFICATIONS)) {
+            if (tabs.get(i).getId().equals(TabDataKt.NOTIFICATIONS)) {
                 notificationTabPosition = i;
-                if(selectNotificationTab) {
+                if (selectNotificationTab) {
                     tab.select();
                 }
             }
@@ -544,7 +557,7 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
                     .withSelectable(false)
                     .withIcon(GoogleMaterial.Icon.gmd_person_add);
             drawer.addItemAtPosition(followRequestsItem, 3);
-        } else if(!me.getLocked()){
+        } else if (!me.getLocked()) {
             drawer.removeItem(DRAWER_ITEM_FOLLOW_REQUESTS);
         }
 
@@ -556,7 +569,7 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
 
         List<AccountEntity> allAccounts = accountManager.getAllAccountsOrderedByActive();
 
-        List<IProfile> profiles = new ArrayList<>(allAccounts.size()+1);
+        List<IProfile> profiles = new ArrayList<>(allAccounts.size() + 1);
 
         for (AccountEntity acc : allAccounts) {
             CharSequence emojifiedName = CustomEmojiHelper.emojifyString(acc.getDisplayName(), acc.getEmojis(), headerResult.getView());
@@ -574,7 +587,7 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
         }
 
         // reuse the already existing "add account" item
-        for (IProfile profile: headerResult.getProfiles()) {
+        for (IProfile profile : headerResult.getProfiles()) {
             if (profile.getIdentifier() == DRAWER_ITEM_ADD_ACCOUNT) {
                 profiles.add(profile);
                 break;
@@ -599,5 +612,4 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
     public AndroidInjector<Fragment> supportFragmentInjector() {
         return fragmentInjector;
     }
-
 }

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationsFragment.kt

@@ -34,6 +34,7 @@ import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.di.Injectable
 import com.keylesspalace.tusky.di.ViewModelFactory
 import com.keylesspalace.tusky.fragment.SFragment
+import com.keylesspalace.tusky.interfaces.ReselectableFragment
 import com.keylesspalace.tusky.interfaces.StatusActionListener
 import com.keylesspalace.tusky.util.NetworkState
 import com.keylesspalace.tusky.util.ThemeUtils
@@ -41,7 +42,7 @@ import com.keylesspalace.tusky.util.hide
 import kotlinx.android.synthetic.main.fragment_timeline.*
 import javax.inject.Inject
 
-class ConversationsFragment : SFragment(), StatusActionListener, Injectable {
+class ConversationsFragment : SFragment(), StatusActionListener, Injectable, ReselectableFragment {
 
     @Inject
     lateinit var viewModelFactory: ViewModelFactory
@@ -52,6 +53,8 @@ class ConversationsFragment : SFragment(), StatusActionListener, Injectable {
 
     private lateinit var adapter: ConversationAdapter
 
+    private var layoutManager: LinearLayoutManager? = null
+
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
         viewModel = ViewModelProviders.of(this, viewModelFactory)[ConversationsViewModel::class.java]
 
@@ -67,10 +70,11 @@ class ConversationsFragment : SFragment(), StatusActionListener, Injectable {
         val mediaPreviewEnabled = account?.mediaPreviewEnabled ?: true
 
 
-        adapter = ConversationAdapter(useAbsoluteTime, mediaPreviewEnabled,this, ::onTopLoaded, viewModel::retry)
+        adapter = ConversationAdapter(useAbsoluteTime, mediaPreviewEnabled, this, ::onTopLoaded, viewModel::retry)
 
         recyclerView.addItemDecoration(DividerItemDecoration(view.context, DividerItemDecoration.VERTICAL))
-        recyclerView.layoutManager = LinearLayoutManager(view.context)
+        layoutManager = LinearLayoutManager(view.context)
+        recyclerView.layoutManager = layoutManager
         recyclerView.adapter = adapter
         (recyclerView.itemAnimator as SimpleItemAnimator).supportsChangeAnimations = false
 
@@ -172,6 +176,17 @@ class ConversationsFragment : SFragment(), StatusActionListener, Injectable {
         }
     }
 
+    private fun jumpToTop() {
+        if (isAdded) {
+            layoutManager?.scrollToPosition(0)
+            recyclerView.stopScroll()
+        }
+    }
+
+    override fun onReselect() {
+        jumpToTop()
+    }
+
     companion object {
         fun newInstance() = ConversationsFragment()
     }

app/src/main/java/com/keylesspalace/tusky/fragment/NotificationsFragment.java

@@ -27,8 +27,6 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
-import com.google.android.material.tabs.TabLayout;
-import com.keylesspalace.tusky.MainActivity;
 import com.keylesspalace.tusky.R;
 import com.keylesspalace.tusky.adapter.NotificationsAdapter;
 import com.keylesspalace.tusky.adapter.StatusBaseViewHolder;
@@ -43,6 +41,7 @@ import com.keylesspalace.tusky.di.Injectable;
 import com.keylesspalace.tusky.entity.Notification;
 import com.keylesspalace.tusky.entity.Status;
 import com.keylesspalace.tusky.interfaces.ActionButtonActivity;
+import com.keylesspalace.tusky.interfaces.ReselectableFragment;
 import com.keylesspalace.tusky.interfaces.StatusActionListener;
 import com.keylesspalace.tusky.util.CollectionUtil;
 import com.keylesspalace.tusky.util.Either;
@@ -97,7 +96,7 @@ public class NotificationsFragment extends SFragment implements
         SwipeRefreshLayout.OnRefreshListener,
         StatusActionListener,
         NotificationsAdapter.NotificationActionListener,
-        Injectable {
+        Injectable, ReselectableFragment {
     private static final String TAG = "NotificationF"; // logging tag
 
     private static final int LOAD_AT_ONCE = 30;
@@ -138,7 +137,6 @@ public class NotificationsFragment extends SFragment implements
     private LinearLayoutManager layoutManager;
     private EndlessOnScrollListener scrollListener;
     private NotificationsAdapter adapter;
-    private TabLayout.OnTabSelectedListener onTabSelectedListener;
     private boolean hideFab;
     private boolean topLoading;
     private boolean bottomLoading;
@@ -250,28 +248,9 @@ public class NotificationsFragment extends SFragment implements
     @Override
     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
-
+        Activity activity = getActivity();
-        MainActivity activity = (MainActivity) getActivity();
         if (activity == null) throw new AssertionError("Activity is null");
 
-        // MainActivity's layout is guaranteed to be inflated until onCreate returns.
-        TabLayout layout = activity.findViewById(R.id.tab_layout);
-        onTabSelectedListener = new TabLayout.OnTabSelectedListener() {
-            @Override
-            public void onTabSelected(TabLayout.Tab tab) {
-            }
-
-            @Override
-            public void onTabUnselected(TabLayout.Tab tab) {
-            }
-
-            @Override
-            public void onTabReselected(TabLayout.Tab tab) {
-                jumpToTop();
-            }
-        };
-        layout.addOnTabSelectedListener(onTabSelectedListener);
-
         /* This is delayed until onActivityCreated solely because MainActivity.composeButton isn't
          * guaranteed to be set until then.
          * Use a modified scroll listener that both loads more notificationsEnabled as it goes, and hides
@@ -323,19 +302,6 @@ public class NotificationsFragment extends SFragment implements
                 });
     }
 
-    @Override
-    public void onDestroyView() {
-        Activity activity = getActivity();
-        if (activity == null) {
-            Log.e(TAG, "Activity is null");
-        } else {
-            TabLayout tabLayout = activity.findViewById(R.id.tab_layout);
-            tabLayout.removeOnTabSelectedListener(onTabSelectedListener);
-        }
-
-        super.onDestroyView();
-    }
-
     @Override
     public void onRefresh() {
         swipeRefreshLayout.setEnabled(true);
@@ -634,8 +600,10 @@ public class NotificationsFragment extends SFragment implements
     }
 
     private void jumpToTop() {
-        layoutManager.scrollToPosition(0);
+        if (isAdded()) {
-        scrollListener.reset();
+            layoutManager.scrollToPosition(0);
+            scrollListener.reset();
+        }
     }
 
     private void sendFetchNotificationsRequest(String fromId, String uptoId,
@@ -974,4 +942,9 @@ public class NotificationsFragment extends SFragment implements
         }
 
     }
+
+    @Override
+    public void onReselect() {
+        jumpToTop();
+    }
 }

app/src/main/java/com/keylesspalace/tusky/fragment/TimelineFragment.java

@@ -28,8 +28,6 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
-import com.google.android.material.tabs.TabLayout;
-import io.reactivex.Observable;
 import com.keylesspalace.tusky.AccountListActivity;
 import com.keylesspalace.tusky.BaseActivity;
 import com.keylesspalace.tusky.R;
@@ -49,6 +47,7 @@ import com.keylesspalace.tusky.di.Injectable;
 import com.keylesspalace.tusky.entity.Filter;
 import com.keylesspalace.tusky.entity.Status;
 import com.keylesspalace.tusky.interfaces.ActionButtonActivity;
+import com.keylesspalace.tusky.interfaces.ReselectableFragment;
 import com.keylesspalace.tusky.interfaces.StatusActionListener;
 import com.keylesspalace.tusky.network.MastodonApi;
 import com.keylesspalace.tusky.repository.Placeholder;
@@ -66,8 +65,8 @@ import com.keylesspalace.tusky.view.BackgroundMessageView;
 import com.keylesspalace.tusky.view.EndlessOnScrollListener;
 import com.keylesspalace.tusky.viewdata.StatusViewData;
 
-import java.util.ArrayList;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
@@ -94,6 +93,7 @@ import androidx.recyclerview.widget.RecyclerView;
 import androidx.recyclerview.widget.SimpleItemAnimator;
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import at.connyduck.sparkbutton.helpers.Utils;
+import io.reactivex.Observable;
 import io.reactivex.android.schedulers.AndroidSchedulers;
 import kotlin.Unit;
 import kotlin.collections.CollectionsKt;
@@ -107,7 +107,7 @@ import static com.uber.autodispose.android.lifecycle.AndroidLifecycleScopeProvid
 public class TimelineFragment extends SFragment implements
         SwipeRefreshLayout.OnRefreshListener,
         StatusActionListener,
-        Injectable {
+        Injectable, ReselectableFragment {
     private static final String TAG = "TimelineF"; // logging tag
     private static final String KIND_ARG = "kind";
     private static final String HASHTAG_OR_ID_ARG = "hashtag_or_id";
@@ -152,7 +152,6 @@ public class TimelineFragment extends SFragment implements
     private String hashtagOrId;
     private LinearLayoutManager layoutManager;
     private EndlessOnScrollListener scrollListener;
-    private TabLayout.OnTabSelectedListener onTabSelectedListener;
     private boolean filterRemoveReplies;
     private boolean filterRemoveReblogs;
     private boolean filterRemoveRegex;
@@ -320,7 +319,7 @@ public class TimelineFragment extends SFragment implements
             @Override
             public void onResponse(@NonNull Call<List<Filter>> call, @NonNull Response<List<Filter>> response) {
                 List<Filter> filterList = response.body();
-                if(response.isSuccessful() && filterList != null) {
+                if (response.isSuccessful() && filterList != null) {
                     applyFilters(filterList, refresh);
                 } else {
                     Log.e(TAG, "Error getting filters from server");
@@ -352,7 +351,7 @@ public class TimelineFragment extends SFragment implements
 
     private static boolean filterContextMatchesKind(Kind kind, List<String> filterContext) {
         // home, notifications, public, thread
-        switch(kind) {
+        switch (kind) {
             case HOME:
                 return filterContext.contains(Filter.HOME);
             case PUBLIC_FEDERATED:
@@ -436,27 +435,6 @@ public class TimelineFragment extends SFragment implements
     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
 
-        if (jumpToTopAllowed()) {
-            TabLayout layout = requireActivity().findViewById(R.id.tab_layout);
-            if (layout != null) {
-                onTabSelectedListener = new TabLayout.OnTabSelectedListener() {
-                    @Override
-                    public void onTabSelected(TabLayout.Tab tab) {
-                    }
-
-                    @Override
-                    public void onTabUnselected(TabLayout.Tab tab) {
-                    }
-
-                    @Override
-                    public void onTabReselected(TabLayout.Tab tab) {
-                        jumpToTop();
-                    }
-                };
-                layout.addOnTabSelectedListener(onTabSelectedListener);
-            }
-        }
-
         /* This is delayed until onActivityCreated solely because MainActivity.composeButton isn't
          * guaranteed to be set until then. */
         if (actionButtonPresent()) {
@@ -543,17 +521,6 @@ public class TimelineFragment extends SFragment implements
         }
     }
 
-    @Override
-    public void onDestroyView() {
-        if (jumpToTopAllowed()) {
-            TabLayout tabLayout = requireActivity().findViewById(R.id.tab_layout);
-            if (tabLayout != null) {
-                tabLayout.removeOnTabSelectedListener(onTabSelectedListener);
-            }
-        }
-        super.onDestroyView();
-    }
-
     @Override
     public void onRefresh() {
         swipeRefreshLayout.setEnabled(true);
@@ -854,7 +821,7 @@ public class TimelineFragment extends SFragment implements
             return;
         }
 
-        if(statuses.size() == 0) {
+        if (statuses.size() == 0) {
             sendInitialRequest();
             return;
         }
@@ -895,19 +862,17 @@ public class TimelineFragment extends SFragment implements
         sendFetchTimelineRequest(null, null, null, FetchEnd.BOTTOM, -1);
     }
 
-    private boolean jumpToTopAllowed() {
-        return kind != Kind.TAG && kind != Kind.FAVOURITES;
-    }
-
     private boolean actionButtonPresent() {
         return kind != Kind.TAG && kind != Kind.FAVOURITES &&
                 getActivity() instanceof ActionButtonActivity;
     }
 
     private void jumpToTop() {
-        layoutManager.scrollToPosition(0);
+        if (isAdded()) {
-        recyclerView.stopScroll();
+            layoutManager.scrollToPosition(0);
-        scrollListener.reset();
+            recyclerView.stopScroll();
+            scrollListener.reset();
+        }
     }
 
     private Call<List<Status>> getFetchCallByTimelineType(Kind kind, String tagOrId, String fromId,
@@ -1325,13 +1290,12 @@ public class TimelineFragment extends SFragment implements
         @Nullable
         @Override
         public Object getChangePayload(@NonNull StatusViewData oldItem, @NonNull StatusViewData newItem) {
-            if (oldItem.deepEquals(newItem)){
+            if (oldItem.deepEquals(newItem)) {
                 //If items are equal - update timestamp only
                 List<String> payload = new ArrayList<>();
                 payload.add(StatusBaseViewHolder.Key.KEY_CREATED);
                 return payload;
-            }
+            } else
-            else
                 // If items are different - update a whole view holder
                 return null;
         }
@@ -1362,5 +1326,8 @@ public class TimelineFragment extends SFragment implements
 
     }
 
-
+    @Override
+    public void onReselect() {
+        jumpToTop();
+    }
 }

app/src/main/java/com/keylesspalace/tusky/interfaces/ReselectableFragment.kt

@@ -0,0 +1,11 @@
+package com.keylesspalace.tusky.interfaces
+
+/**
+ * Created by pandasoft (joelpyska1@gmail.com) on 04/04/2019.
+ */
+interface ReselectableFragment {
+    /**
+     * Call this method when tab reselected
+     */
+    fun onReselect()
+}

app/src/main/java/com/keylesspalace/tusky/pager/AccountPagerAdapter.java

@@ -15,17 +15,25 @@
 
 package com.keylesspalace.tusky.pager;
 
+import android.util.SparseArray;
+import android.view.ViewGroup;
+
 import com.keylesspalace.tusky.fragment.AccountMediaFragment;
 import com.keylesspalace.tusky.fragment.TimelineFragment;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentPagerAdapter;
 
 public class AccountPagerAdapter extends FragmentPagerAdapter {
+    private static final int TAB_COUNT = 4;
     private String accountId;
     private String[] pageTitles;
 
+    private SparseArray<Fragment> fragments = new SparseArray<>(TAB_COUNT);
+
     public AccountPagerAdapter(FragmentManager manager, String accountId) {
         super(manager);
         this.accountId = accountId;
@@ -58,11 +66,31 @@ public class AccountPagerAdapter extends FragmentPagerAdapter {
 
     @Override
     public int getCount() {
-        return 4;
+        return TAB_COUNT;
+    }
+
+    @NonNull
+    @Override
+    public Object instantiateItem(@NonNull ViewGroup container, int position) {
+        Object fragment = super.instantiateItem(container, position);
+        if (fragment instanceof Fragment)
+            fragments.put(position, (Fragment) fragment);
+        return fragment;
+    }
+
+    @Override
+    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
+        super.destroyItem(container, position, object);
+        fragments.remove(position);
     }
 
     @Override
     public CharSequence getPageTitle(int position) {
         return pageTitles[position];
     }
+
+    @Nullable
+    public Fragment getFragment(int position) {
+        return fragments.get(position);
+    }
 }

app/src/main/java/com/keylesspalace/tusky/pager/MainPagerAdapter.kt

@@ -15,6 +15,8 @@
 
 package com.keylesspalace.tusky.pager
 
+import android.util.SparseArray
+import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentManager
 import androidx.fragment.app.FragmentPagerAdapter
@@ -22,6 +24,7 @@ import androidx.viewpager.widget.PagerAdapter
 import com.keylesspalace.tusky.TabData
 
 class MainPagerAdapter(val tabs: List<TabData>, manager: FragmentManager) : FragmentPagerAdapter(manager) {
+    private val fragments = SparseArray<Fragment>(tabs.size)
 
     override fun getItem(position: Int): Fragment {
         val tab = tabs[position]
@@ -44,4 +47,17 @@ class MainPagerAdapter(val tabs: List<TabData>, manager: FragmentManager) : Frag
         return PagerAdapter.POSITION_NONE
     }
 
+    override fun instantiateItem(container: ViewGroup, position: Int): Any {
+        val fragment = super.instantiateItem(container, position)
+        if (fragment is Fragment)
+            fragments.put(position, fragment)
+        return fragment
+    }
+
+    override fun destroyItem(container: ViewGroup, position: Int, `object`: Any) {
+        super.destroyItem(container, position, `object`)
+        fragments.remove(position)
+    }
+
+    fun getFragment(position: Int): Fragment? = fragments[position]
 }