NullPointer on LayoutInflater - Android

问题

I have a class in another java file that I'm calling in my MainActivity. I need to inflate some layouts in the external class. The problem I'm having is specifying the context, because when I try to inflate the layouts I get a Null Pointer Exception. The class doesn't have it's own onCreate() method so I need to pass the context from my MainActivity? Not sure how to go about it. This is causing me the NullPointerException:

Context context = getApplicationContext();
LayoutInflater inflater = (LayoutInflater)context.getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);;

NullPointerException on Context context:

public class CameraListener extends Activity implements OnCameraChangeListener {

    private static final int SCALE_HEIGHT = 50;
    GoogleMap mMap;
    GoogleC3iActivity mParent;


    Context context = getApplicationContext();

回答1:

Multiple Issues

First

Context context = getApplicationContext();
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

You shouldn't need the getApplicationContext(), since you already have it.

OR (credits : @Delyan)

LayoutInflater.from(context)

Second

Context context = getApplicationContext(); does not work before setContentView. So you need to initialize context after you call setContentView in your onCreate

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home);
    context = getApplicationContext() ;

Same goes for LayoutInflater, you need to initialize it in the onCreate

回答2:

Activity extends from Context that means you just need LayoutInflater inflater = LayoutInflater.from(this); in your onCreate() method.

来源：https://stackoverflow.com/questions/17429205/nullpointer-on-layoutinflater-android

标签

android

nullpointerexception

android-context