Android Utils

This library collects a range of Android classes that I often use in projects.

Usage

Avoid adding padding to recycler view item XML files and use item decoration instead. The class SpacesItemDecoration can be used to add space between items. It can be used several times to provide different values for HORIZONTAL and VERTICAL orientations.

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.addItemDecoration(new SpacesItemDecoration(16, SpacesItemDecoration.VERTICAL));

The DisplayHelper class provides a range of functions for screen measurement and to find suitable layout managers for RecyclerView based on the screen width:

recyclerView.setLayoutManager(DisplayHelper.getSuitableLayoutManager(this));

Array-based adapters are the most common recycler view adapters. Avoid re-inventing the whell and subclass from ArrayAdapter:

public final class MyArrayAdapter extends ArrayAdapter<Thing, MyArrayAdapter.MyViewHolder> {
    public MyArrayAdapter(List<Thing> objects) {
        super(objects);
        // ...
    }
    
    static final class MyViewHolder extends RecyclerView.ViewHolder {
        // ...
    }
}
 
public final class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        List<Thing> things = new ArrayList<>();
        
        MyAdapter adapter = new Adapter(things);
        
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        recyclerView.setAdapter(adapter);
    }
}

The recycler view library does not provide Cursor-based adapters. Use CursorRecyclerAdapter to directly display database data:

public final class EventAdapter extends CursorRecyclerAdapter<EventAdapter.EventViewHolder> {
    public EventAdapter(@NonNull Context context) {
        // ...
        Cursor cursor = context.getContentResolver()
                .query(eventsUri, PROJECTION, SELECTION, selectionArgs,
                        CalendarContract.Instances.DTSTART + " ASC");
    
        init(cursor); // See base class
    }
    
    @Override
    public EventViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // ...
        return new EventViewHolder(v);
    }
    
    @Override
    public void onBindViewHolderCursor(final EventViewHolder holder, final Cursor cursor) {
        // ...
    }
    
    static class EventViewHolder extends RecyclerView.ViewHolder {
        // ...
    }
}

The Android SDK does not provide a PreferenceActivity that is based on AppCompat. To avoid using the old and deprecated PreferenceActivity or rolling your own, subclass from AppCompatPreferenceActivity instead:

public final class SettingsActivity extends AppCompatPreferenceActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
    }
    // ...
}

Download

compile 'saschpe.android:utils:2.0.0'

Snapshots of the development version are available in Sonatype's snapshots repository.

In use by

• Alpha+ Player
• Birthday Calendar - Open Source on Github
• Planning Poker - Open Source on Github

License

Copyright 2016 Sascha Peilicke

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.