I'm trying to open and populate a navigation drawer with a separate fragment by clicking on a button. The drawers themselves are only empty RelativeLayouts declared in activity_main.xml.
activity_main.xml:
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!--Main View-->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="xxx.MainActivity">
</RelativeLayout>
<!--Left drawer-->
<RelativeLayout android:id="@+id/drawer_left"
android:layout_width="290dp"
android:layout_height="match_parent"
android:layout_gravity="start">
</RelativeLayout>
<!--Right drawer-->
<RelativeLayout android:id="@+id/drawer_right"
android:layout_width="290dp"
android:layout_height="match_parent"
android:layout_gravity="end">
</RelativeLayout>
The main_view gets populated with a fragment in MainActivity, so it will look like this:
MainActivity class:
public class MainActivity extends AppCompatActivity {
android.app.FragmentManager fragmentManager;
android.app.FragmentTransaction fragmentTransaction;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManager = getFragmentManager();
//Set fragment
Frag1 frag1 = new Frag1();
fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.fragment_container,frag1).commit();
}
Frag1 class:
public class Frag1 extends Fragment {
ImageButton imageButtonOpenDrawer;
DrawerLayout mDrawerLayout;
RelativeLayout mDrawer_left;
android.app.FragmentManager fragmentManager;
android.app.FragmentTransaction fragmentTransaction;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.frag1, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
View v = getView();
imageButtonOpenDrawer = (ImageButton) v.findViewById(R.id.imageButtonOpenDrawer);
fragmentManager = getFragmentManager();
mDrawerLayout = (DrawerLayout) v.findViewById(R.id.drawer_layout);
mDrawer_left = (RelativeLayout) v.findViewById(R.id.drawer_left);
imageButtonOpenDrawer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DrawerFragment drawerFragment = new DrawerFragment();
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.fragment_container,drawerFragment).commit();
}
});
}
The same principle works when done from MainActivity class. But when I try to open the drawer from the fragments class, this null pointer error gets thrown:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.widget.DrawerLayout.openDrawer(android.view.View)' on a null object reference
