CODEWITHSUNDEEP
javaandroidnullpointerexceptionandroid-support-library
Kenny Wyland
Kenny Wyland

Reputation: 21870

v7 getSupportActionBar() is throwing NullPointerException

I'm launching a new activity (TVMPDFActivity) from my root activity. I'm using Android Annotations, so this is how I'm launching the Activity:

TVMPDFActivity_.intent(this.getActivity()).start();

TVMPDFActivity is a subclass of PDFPreviewActivity which is a subclass of ActionBarActivity.

A NullPointerException is being thrown from onCreate in PDFPreviewActivity when I simply try to GET the ActionBar. On this line:

final ActionBar actionBar = getSupportActionBar();

Here is the stacktrace from my code to the NPE:

Caused by: java.lang.NullPointerException
    at android.support.v7.internal.app.WindowDecorActionBar.getDecorToolbar(WindowDecorActionBar.java:248)
    at android.support.v7.internal.app.WindowDecorActionBar.init(WindowDecorActionBar.java:201)
    at android.support.v7.internal.app.WindowDecorActionBar.<init>(WindowDecorActionBar.java:176)
    at android.support.v7.app.ActionBarActivityDelegateBase.createSupportActionBar(ActionBarActivityDelegateBase.java:156)
    at android.support.v7.app.ActionBarActivityDelegate.getSupportActionBar(ActionBarActivityDelegate.java:123)
    at android.support.v7.app.ActionBarActivity.getSupportActionBar(ActionBarActivity.java:73)
    at com.my.app.PDFPreviewActivity.onCreate(PDFPreviewActivity.java:63)
    at com.my.app.TVMPDFActivity.onCreate(TVMPDFActivity.java:24)
    at com.my.app.TVMPDFActivity_.onCreate(TVMPDFActivity_.java:31)

Here are the onCreate methods of the various classes involved:

public class TVMPDFActivity extends PDFPreviewActivity {

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

public abstract class PDFPreviewActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final ActionBar actionBar = getSupportActionBar(); // throws NullPointerException
        ...
    }
}

Why am I getting a NullPointerException from deep within the support v7 code?

Upvotes: 2

Views: 4383

Answers (1)

Blackbelt
Blackbelt

Reputation: 157457

you should call super.onCreate before setContentView in TVMPDFActivity in order to give android the opportunity to initialize its internal state, before trying to access something that relies on that internal state. For onCreate/onStart/onResume call the super always as first statement

Upvotes: 1

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