FloatingActionButton onclick error

[Radzhab]

public class ViewPagerTabScrollViewActivity extends BaseActivity implements ObservableScrollViewCallbacks {
    private View mHeaderView;
    private View mToolbarView;
    private int mBaseTranslationY;
    private ViewPager mPager;
    private NavigationAdapter mPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_viewpagertab);

        setSupportActionBar((Toolbar) findViewById(R.id.toolbar));

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (event.getAction() == MotionEvent.ACTION_UP) {
                    // Do what you want
                    return true;
                }
                return true; // consume the event
            }
        });```

this code return error

```log
   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.github.ksoichiro.android.observablescrollview.samples.debug/com.github.ksoichiro.android.observablescrollview.samples.ViewPagerTabScrollViewWithFabActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2349)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2376)
            at android.app.ActivityThread.access$600(ActivityThread.java:163)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1322)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5228)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:826)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:589)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.github.ksoichiro.android.observablescrollview.samples.ViewPagerTabScrollViewActivity.onCreate(ViewPagerTabScrollViewActivity.java:63)
            at android.app.Activity.performCreate(Activity.java:5032)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2301)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2376)
            at android.app.ActivityThread.access$600(ActivityThread.java:163)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1322)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5228)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:826)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:589)
            at dalvik.system.NativeStart.main(Native Method)