getSupportActionBar(toolbar) throws null pointer exception using with Butterknife for toolbar

Question

I am using Butterknife to inject view for the toolbar. But the method getSupportActionBar(toolbar) throws null pointer exception and the app unfortunately stopped. What can be done to solve this issue? I am using Android 4.2. So, is there any problem of using Butterknife with Jellybean?

MainActivity

    public class MainActivity extends AppCompatActivity {

    @BindView(R.id.tool_bar_demo)
    Toolbar toolbar;
    @BindDrawable(R.drawable.backspace)
    Drawable backspace_btn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        setSupportActionBar(toolbar);
        toolbar.setTitle("ABC");
    }
}

activity_main

    <android.support.v7.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:id="@+id/tool_bar_demo"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        android:titleTextColor="@color/colorAccent"
        />

</RelativeLayout>

gradle

    minSdkVersion 15
    targetSdkVersion 23

    apply plugin: 'com.neenbedankt.android-apt'
    compile 'com.android.support:design:23.4.0'
    compile 'com.jakewharton:butterknife:8.0.1'
    apt 'com.jakewharton:butterknife-compiler:8.0.1'


    classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'

Answer 1

This seems to be a issue with Butterknife.

From the issue the main points collected are:

Butter Knife is just sugar on findViewById, and that's what is failing to find the view. As I said, make sure that layout is in main_activity or ensure you put a Toolbar with that ID in main_activity layout.

another comment says: if i set an id to my include like this :

<include
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    layout="@layout/toolbar"
    android:id="@+id/include4" />

That doesn't work. But if i remove the android:id="@+id/include4" it works. As of version 7.0.1, adding an ID to the include causes the view to not be found.

The link to the issue: id issue of butterknife

Answer 2

In fact it's not related to Butterknife or Jellybean. It's common exception that happen when you use ActionBar theme with Toolbar. And it's says you can't use ActionBar & Toolbar at the same time.

As I mention in comment you should change your style to following:

<style name="YOUR_STYLE" parent="Theme.AppCompat.Light.NoActionBar">
 .... other attrs here
<item name="windowActionBar">false</item>
</style>

See this related thread to solve your issue.