view_keypad.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_gravity="bottom"
                android:padding="@dimen/keypad_size"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
    android:id="@+id/keypad">

    <Button android:id="@+id/keypad_up"
            android:layout_alignParentTop="true"
            android:layout_toRightOf="@+id/keypad_left"
            android:layout_width="@dimen/keypad_size"
            android:layout_height="@dimen/keypad_size" />

    <Button android:id="@+id/keypad_down"
            android:layout_below="@+id/keypad_left"
            android:layout_toRightOf="@+id/keypad_left"
            android:layout_width="@dimen/keypad_size"
            android:layout_height="@dimen/keypad_size" />

    <Button android:id="@+id/keypad_left"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/keypad_up"
            android:layout_width="@dimen/keypad_size"
            android:layout_height="@dimen/keypad_size" />

    <Button android:id="@+id/keypad_right"
            android:layout_toRightOf="@+id/keypad_up"
            android:layout_below="@+id/keypad_up"
            android:layout_width="@dimen/keypad_size"
            android:layout_height="@dimen/keypad_size" />

    <Button android:id="@+id/keypad_jump"
            android:layout_alignParentRight="true"
            android:layout_alignTop="@+id/keypad_left"
            android:layout_width="@dimen/keypad_size"
            android:layout_height="@dimen/keypad_size" />
</RelativeLayout>


//update styles.xml with fullscreen-flags
	<item name="android:windowNoTitle">true</item>
	<item name="android:windowActionBar">false</item>
	<item name="android:windowFullscreen">true</item>
	<item name="android:windowContentOverlay">@null</item>
	<item name="android:immersive">true</item>


//activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context="com.ulfben.platformer.MainActivity">

    <view class="com.ulfben.platformer.GameView"
          android:id="@+id/gameView"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"/>

    <include layout="@layout/view_keypad" />
</FrameLayout>

//constructors needed for view-inflation to not crash horribly
public GameView(Context context) {
	super(context);
	init(context);
}
public GameView(Context context, AttributeSet attrs) {
	super(context, attrs);
	init(context);
}
public GameView(Context context, AttributeSet attrs, int defStyle) {
	super(context, attrs, defStyle);
	init(context);
}


//BasicInputManager.java
BasicInputManager(View view){
        view.findViewById(R.id.keypad_up).setOnTouchListener(this); 
        view.findViewById(R.id.keypad_down).setOnTouchListener(this);
        view.findViewById(R.id.keypad_left).setOnTouchListener(this);
        view.findViewById(R.id.keypad_right).setOnTouchListener(this);
        view.findViewById(R.id.keypad_jump).setOnTouchListener(this);
    }
	
@Override
public boolean onTouch(final View v, final MotionEvent event) {
	int action = event.getActionMasked();
	int id = v.getId();
	if(action == MotionEvent.ACTION_DOWN){// User started pressing a key
		if(id == R.id.keypad_up){
			mVerticalFactor -= 1;
		}else if (id == R.id.keypad_down) {
			mVerticalFactor += 1;
		}
		if (id == R.id.keypad_left) {
			mHorizontalFactor -= 1;
		} else if(id == R.id.keypad_right) {
			mHorizontalFactor += 1;
		}
		if (id == R.id.keypad_jump) {
			mIsJumping = true;
		}
	} else if(action == MotionEvent.ACTION_UP) {
		if (id == R.id.keypad_up) {
			mVerticalFactor += 1;
		} else if (id == R.id.keypad_down) {
			mVerticalFactor -= 1;
		}
		if (id == R.id.keypad_left) {
			mHorizontalFactor += 1;
		} else if (id == R.id.keypad_right) {
			mHorizontalFactor -= 1;
		}
		if (id == R.id.keypad_jump) {
			mIsJumping = false;
		}
	}
	return false;
}