Android subTitle show array count error

Question

I have created an ArrayList with count

 private ArrayList<GeoJsonResponse> localGeoJsonResponse;
FeatureCollection featureCollection;
GeoJsonResponse data = null;
Integer number = localGeoJsonResponse.size();
String str = Integer.toString(number);
String event= str + " total event";

I have to set a value of the count on sub title of action bar and this is my code

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);

    ActionBar ab = getActionBar();
    ab.setDisplayHomeAsUpEnabled(true);
    ab.setHomeButtonEnabled(true);
    ab.setBackgroundDrawable(new ColorDrawable(getResources().getColor(R.color.theme_color)));
    ab.setTitle(R.string.mappa);
    ab.setSubtitle(event);

I receive an error when i call this view. In the setSubtitle I can set only String, example

ab.setSubtitle("events");

rest of the view works well. Any help please? Thanks

this is the log of error

Caused by: java.lang.NullPointerException
        at com.###.###.###.MyMapActivity.onCreate(MyMapActivity.java:164)
        at android.app.Activity.performCreate(Activity.java:5133)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
        at

thanks

score 0 · Answer 1 · answered Aug 16 '15 at 14:40

There are two possible places in your code where NullPointerException may occur:

Your localGeoJsonResponse wasn't initialised but you call

localGeoJsonResponse.size(); -> which may result in null pointer

You have to do as @Teodor Liv's answer:

ArrayList<GeoJsonResponse> localGeoJsonResponse = new ArrayList<GeoJsonResponse>();

Another one is that you don't really get the ActionBar object, so when you call:

ab.setDisplayHomeAsUpEnabled(true); -> This may cause null pointer

For checking, you can do like this:

ActionBar ab = getAcionBar();
if (ab != null) {
    ab.setDisplayHomeAsUpEnabled(true);
    ab.setHomeButtonEnabled(true);
    ab.setBackgroundDrawable(new ColorDrawable(getResources().getColor(R.color.theme_color)));
    ab.setTitle(R.string.mappa);
    ab.setSubtitle(event);
} else {
    Log.e(TAG, "fail to get ActionBar");
}

Android subTitle show array count error

1 Answers1