App crash with actionbar - android-actionbar

Question

i'm new on Android. I'm trying to implent an actionbar im my activity. Everytime i run that, the app crash.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_percorsodisabili);
//Option Bar
getSupportActionBar().setTitle("Percorso Bici");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Resources res = getResources();
myVist3 = (ListView) findViewById(R.id.myVist3);
items = res.getStringArray(R.array.nomi_percorsi3);
descriptions = res.getStringArray(R.array.desc_percorsi3);
content = res.getStringArray(R.array.desc_percorsi3);
ItemAdapter itemAdapter = new ItemAdapter(percorsodisabili.this, items,foto,descriptions,content);
myVist3.setAdapter(itemAdapter);
}
}

Answer 1

Add the toolbar to your activity layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="wrap_content"
android:layout_height="56dp" />
<RelativeLayout
android:id="#+id/content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/toolbar">
<!--YOUR LAYOUT CODE-->
</RelativeLayout>
Then initialize java code for activity:
Use android.support.v7.widget.Toolbar in case you are using AppCompactActivity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_third);
Toolbar toolbar=findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}