my app crash after open one activity with ListView.My intention is show the names of the Firebase Real time Data Basebut with this error this is impossible
Code XML :
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_gravity="center" android:orientation="vertical" ><ListView android:id="@+id/ListView1" android:layout_width="match_parent" android:layout_height="match_parent"/></RelativeLayout>Code.java :
import android.os.Bundle;import android.widget.ArrayAdapter;import android.widget.ListView;import androidx.annotation.NonNull;import androidx.annotation.Nullable;import androidx.appcompat.app.AppCompatActivity;import com.google.firebase.database.ChildEventListener;import com.google.firebase.database.DataSnapshot;import com.google.firebase.database.DatabaseError;import com.google.firebase.database.DatabaseReference;import com.google.firebase.database.FirebaseDatabase;import java.util.ArrayList;public class Drinks extends AppCompatActivity {ListView ListView1;ArrayList<String> MyArrayList = new ArrayList<>();DatabaseReference mRef; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_drinks); final ArrayAdapter<String> MyArrayAdapter = new ArrayAdapter<String>(Drinks.this,android.R.layout.simple_list_item_1,MyArrayList); ListView1 = (ListView) findViewById(R.id.ListView1); ListView1.setAdapter(MyArrayAdapter); mRef = FirebaseDatabase.getInstance().getReference().child("Main"); mRef.addChildEventListener(new ChildEventListener() { @Override public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) { String value = snapshot.getValue(String.class); MyArrayList.add(value); MyArrayAdapter.notifyDataSetChanged(); } @Override public void onChildChanged(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) { MyArrayAdapter.notifyDataSetChanged(); } @Override public void onChildRemoved(@NonNull DataSnapshot snapshot) { } @Override public void onChildMoved(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) { } @Override public void onCancelled(@NonNull DatabaseError error) { } }); }}
