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tabstack

Tab Stacker is an Android library that handles Multiple Fragment History (Back Stacks), like it is done on iOS Apps.

smart-fun/TabStacker00

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README.md

Tab Stacker

Tab Stacker is an Android library that handles Multiple Fragment History, like it is done on iOS Apps.

alt text

Each Tab has its own stack of Fragments, that can be added, replaced or removed using animations. When the user presses back, the top Fragment from the current Tab stack is dismissed.

When a complete stack is removed and restored (during a Tab change, or a system cleanup like when rotating the device), a save and restore mechanism allows you to keep your Fragments up-to-date.

Tab Stacker uses Support Fragments. It is recommended to always use Support Fragments as they are compatible with older devices, and the last bugs are fixed for all devices. See how to migrate to Support Fragment in the wiki.

How to use##

Like any Tabbed application, you need a placeholder where put the Fragments.

<?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="match_parent"
    android:orientation="vertical" >

    <!-- This is the Fragment Holder -->
    <FrameLayout
        android:id="@+id/fragmentHolder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="100" />

    <!-- Here you could include your bottom bar with tabs -->
    <include
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        layout="@layout/myCustomTabs" />

</LinearLayout>

At Activity creation, you need to create the TabStacker, and restore its state by calling restoreInstance.

When the activity is saving its state, you also need to save the TabStacker state. Call the TabStacker.saveInstance() before super.saveInstance() so that the TabStacker takes the hand in the save / restore process of the Fragments.

public class MainActivity extends FragmentActivity {

    private TabStacker mTabStacker;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main_activity);

        mTabStacker = new TabStacker(getSupportFragmentManager(), R.id.fragmentHolder);
        
        if (savedInstanceState != null) {
            mTabStacker.restoreInstance(savedInstanceState);
            String selectedTab = mTabStacker.getCurrentTabName();
            // do something like highlight the selected tab...
        }
    }
    
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        // Keep this first
        if (mTabStacker != null) {
            mTabStacker.saveInstance(outState);
        }

        super.onSaveInstanceState(outState);
    }
    
    // will be called by the Fragments when they build their view, so that the View hierarchy will be retored.
    public void restoreView(Fragment fragment, View view) {
        mTabStacker.restoreView(fragment, view);
    }
    
}

    @Override
    public void onBackPressed() {
        if (!mTabStacker.onBackPressed()) {
            super.onBackPressed();
        }
    }

    // optional animation
    AnimationSet animation = new AnimationSet(R.anim.slide_from_right, R.anim.slide_to_left, R.anim.slide_from_left, R.anim.slide_to_right);

    mTabStacker.addFragment(fragment, animation);
    // OR
    mTabStacker.replaceFragment(fragment, animation);

    private void onClickOnTab(String tabName) {
        if (!mTabStacker.switchToTab(tabName)) {    // Try to switch to the TAB STACK
            // no fragment yet on this stack -> push the 1st fragment of the stack
            MyFragment fragment = MyFragment.createInstance(some parameters if necessary);
            mTabStacker.replaceFragment(fragment, null);  // no animation
        }
    }

import android.support.v4.app.Fragment;


public class MyFragment extends Fragment implements TabStacker.TabStackInterface {

    @Override
    public void onTabFragmentPresented(TabStacker.PresentReason reason) {
    }

    @Override
    public void onTabFragmentDismissed(TabStacker.DismissReason reason) {
    }

    @Override
    public View onSaveTabFragmentInstance(Bundle outState) {
    }

    @Override
    public void onRestoreTabFragmentInstance(Bundle savedInstanceState) {
    }

}


public class MyFragment extends Fragment implements TabStacker.TabStackInterface {

    private static final String ARGUMENT_TITLE = "title";
    private static final String DYNAMIC_IMPORTANT = "important";
    
    private View mView;		// keep a reference to the inflated view

    // createInstance() pattern with arguments
    public static MyFragment createInstance(String title) {
        MyFragment fragment = new MyFragment();
        Bundle bundle = new Bundle();
        bundle.putString(ARGUMENT_TITLE, title);
        fragment.setArguments(bundle);
        return fragment;
    }
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        mView = inflater.inflate(R.layout.testfragment, container, false);
        return mView;
    }
    
    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // retrieve the arguments to set the Title
        Bundle arguments = getArguments();
        String title = arguments.getString(ARGUMENT_TITLE);
        TextView titleView = (TextView) view.findViewById(R.id.titleView);
        titleView.setText(title);
        
        // Restore the View hierarchy (the Activity holds the TabStacker)
        MainActivity activity = (MainActivity) getActivity();
        activity.restoreView(this, view);
        
    }
    
        @Override
    public View onSaveTabFragmentInstance(Bundle outState) {
        outState.putString(DYNAMIC_IMPORTANT, "my important string to save");
        return mView;	// so that the View hierarchy can be saved
    }

    @Override
    public void onRestoreTabFragmentInstance(Bundle savedInstanceState) {
        String importantString = savedInstanceState.getString(DYNAMIC_IMPORTANT);
    }

}

allprojects {
    repositories {
        jcenter()
        maven { url "https://jitpack.io" }    // add this line
    }
}

dependencies {
    implement 'com.github.smart-fun:TabStacker:1.0.4'    // add this line
}

// code in Activity
if (isActive()) { // be sure that the Activity is still there
    mTabStacker.replaceFragment(...)
}

// or code in Fragment
Activity activity = getActivity();
if ((activity != null) && !isDetached()) { // be sure the fragment is still there
    activity.doSomethingWithTheFragment();
}

    try {
        mTabStacker.replaceFragment(...);
    } catch (IllegalStateException exception) {
        // too bad but it did not crash at least
    }