Show the soft keyboard on activity startup

In AndroidManifest.xml:

<activity
    android:windowSoftInputMode="stateVisible"
    ...>
</activity>

Ways to set colours in resource XML files

android:background="@android:color/white"

android:background="#FFF9C4"

Disable fullscreen keyboard in landscape orientation for an EditText

<EditText
    android:imeOptions="flagNoExtractUi"
    ... />

Set Toolbar as the app bar (instead of the default ActionBar)

1. In AndroidManifest.xml set the application theme to one of the NoActionBar themes, e.g.:

    <application
        android:theme="@style/Theme.AppCompat.Light.NoActionBar"
        ...>
   

2. Add a Toolbar to the activity’s layout:

    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:orientation="vertical"
        ...>
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            android:elevation="4dp"
            app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />
        ...
    </LinearLayout>
   

3. Set the Toolbar as the app bar in the activity’s onCreate method:

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
   
        setSupportActionBar((Toolbar) findViewById(R.id.toolbar));
        ...
    }
   

Prevent contextual action bar from pushing down Toolbar

By default, the contextual action bar pushes the Toolbar down rather than overlaying it. This can be changed with the following item in the app style in res/styles.xml:

<style name="AppTheme.NoActionBar" parent="Theme.AppCompat.Light.NoActionBar">
    ...
    <item name="windowActionModeOverlay">true</item>
</style>

Prevent an activity from being added to the “back stack”

In AndroidManifest.xml:

<activity
    ...
    android:noHistory="true">
</activity>

Make soft keyboard pushing up views rather than hiding them

In AndroidManifest.xml:

<activity
    ...
    android:windowSoftInputMode="adjustResize">
</activity>

Enable “back” navigation item in app bar and set custom icon

First, in AndroidManifest.xml, define the parent activity of the current activity:

<activity
   ...
   android:parentActivityName="...">
</activity>

Then, in the activity’s onCreate:

getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_close_white_24dp);

When clicking navigation icon in app bar, just restart (onRestart) parent activity, rather than recreating it (onCreate)

In the child activity:

@Override
public boolean onSupportNavigateUp() {
    onBackPressed();
    return true;
}

Fix version conflicts of Google Support Library Gradle dependencies

For example, if a pulled project uses compile 'com.android.support:appcompat-v7:25.2.0', but this causes an error when syncing the Gradle file, because only 'com.android.support:appcompat-v7:25.1.0' is installed.

SDK Manager > Launch Standalone SDK Manager > Extras > Android Support Repository $\longleftarrow$ update it

Replace all anonymous classes with lambda expressions

1. Analyze > Run Inspection by Name (Cmd-Alt-Shift-I)
2. Type “Anonymous type can be replaced with lambda”
3. Select Whole project
4. In Inspection tool window, right-click on “Anonymous type…”
5. Click Apply fix

Creating a launcher icon

The radius of the corners should be 8.33% of the size of the icon (http://stackoverflow.com/questions/31255291/android-launcher-icon-rounded-corner-edge-radii)