CynthiaDDurazo CynthiaDDurazo - 1 month ago 16
Android Question

How to open Navigation Drawer with no actionbar, open with just a button

I have a navigation bar without any actionbar (I don't want an actionbar). I'm trying to make it so that I have a button that can open the navigation drawer.

I know there's a method called openDrawer for the DrawerLayout
http://developer.android.com/reference/android/support/v4/widget/DrawerLayout.html#openDrawer(android.view.View)

I didn't know how to use it, but i have tried making a button when click, runs this method:

DrawerLayout mDrawerLayout = (DrawerLayout) getView().findViewById(R.id.drawer_layout);
mDrawerLayout.openDrawer(mDrawerLayout);


When i click it on it, it gives me a Java NullPointerException. Anybody has any idea?

EDIT:
This code is inside a fragment, and I'm trying to refer those drawer layout outside the fragment. I used debugger, and it is showing that mDrawlerLayout is NULL.

Any advice?

Thanks!

Answer

It's giving you a null pointer because you are trying to find the drawer layout in the fragment's view, when it is actually in the activities view.

A quick hack to do what you want is to find the view like:

getActivity().findViewById(R.id.drawer_layout)

That should work. A better way is to have a method on the activity for opening the drawer

public void openDrawer(){
    mDrawerLayout.openDrawer(mDrawerLayout);
}

In the activity onCreate run your findViewById:

mDrawerLayout = (DrawerLayout) getView().findViewById(R.id.drawer_layout);

mDrawerLayout should be a member variable of your activity.

Then in your fragment you can call:

//cast activity to MyActivity so compiler doesn't complain
((MyActivity)getActivity()).openDrawer();

An even better way to do it is to create a listener in the fragment and set the activity as a listener to the fragment. Then you can call a method on the activity, similar to above. I'll let you do some research on how to do that.