当我尝试将应用程序中的数据从firebase检索到RecyclerView并且我的应用程序崩溃时，我在logcat中收到此消息。下面是我用来从firebase数据库中检索数据的java代码。应用程序显示空白屏幕，当我在真实设备上打开它时，它一直崩溃。还有其他办法吗？
在Android 4.1之前，方法int android.support.v7.widget.ListViewCompat.lookForSelectablePosition（INT， boolean）会错误地重写package-private方法 在android.widget.ListView
中
public class Home extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
FirebaseDatabase database;
DatabaseReference category;
TextView txtFullName;
RecyclerView recycler_menu;
RecyclerView.LayoutManager layoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Menu");
setSupportActionBar(toolbar);
//init firebase
database=FirebaseDatabase.getInstance();
category=database.getReference("category");
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
// Set name for user
View headerView=navigationView.getHeaderView(0);
txtFullName=(TextView)headerView.findViewById(R.id.txtFullName);
txtFullName.setText(Common.currentUser.getName());
//load menu
recycler_menu=(RecyclerView)findViewById(R.id.recycler_menu);
recycler_menu.setHasFixedSize(true);
layoutManager=new LinearLayoutManager(this);
recycler_menu.setLayoutManager(layoutManager);
loadMenu();
}
private void loadMenu() {
FirebaseRecyclerAdapter<Category,MenuViewHolder> adapter=new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class,R.layout.menu_item,MenuViewHolder.class,category) {
@Override
protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {
viewHolder.txtMenuName.setText(model.getName());
Picasso.with(getBaseContext()).load(model.getImage())
.into(viewHolder.imageView);
final Category clickItem=model;
viewHolder.setItemClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
Toast.makeText(Home.this,""+clickItem.getName(),Toast.LENGTH_SHORT).show();
}
});
}
};
recycler_menu.setAdapter(adapter);
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_menu) {
// Handle the camera action
} else if (id == R.id.nav_cart) {
} else if (id == R.id.nav_orders) {
} else if (id == R.id.nav_log_out) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
答案 0 :(得分：0)
尝试在recyclerview中使用此适配器
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
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 java.util.ArrayList;
import java.util.List;
import illumine.ibecome.R;
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {
private Context mContext;
private DatabaseReference mDatabaseReference;
private ChildEventListener mChildEventListener;
private List<String> mCommentIds = new ArrayList<>();
private List<MyModel> mComments = new ArrayList<>();
private static final String TAG = "ActivityName";
public MyRecyclerViewAdapter(final Context context, DatabaseReference ref) {
mContext = context;
mDatabaseReference = ref;
ChildEventListener childEventListener = new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
// A new comment has been added, add it to the displayed list
MyModel comment = dataSnapshot.getValue(MyModel.class);
// Log.d(TAG, "onChildAdded:" + dataSnapshot.getKey()+" with module: "+comment.modules.get(0));
// [START_EXCLUDE]
// Update RecyclerView
mCommentIds.add(dataSnapshot.getKey());
mComments.add(comment);
notifyItemInserted(mComments.size() - 1);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String previousChildName) {
Log.d(TAG, "onChildChanged:" + dataSnapshot.getKey());
// A comment has changed, use the key to determine if we are displaying this
// comment and if so displayed the changed comment.
MyModel newComment = dataSnapshot.getValue(MyModel.class);
String commentKey = dataSnapshot.getKey();
// [START_EXCLUDE]
int commentIndex = mCommentIds.indexOf(commentKey);
if (commentIndex > -1) {
// Replace with the new data
mComments.set(commentIndex, newComment);
// Update the RecyclerView
notifyItemChanged(commentIndex);
} else {
Log.w(TAG, "onChildChanged:unknown_child:" + commentKey);
}
// [END_EXCLUDE]
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
Log.d(TAG, "onChildRemoved:" + dataSnapshot.getKey());
// A comment has changed, use the key to determine if we are displaying this
// comment and if so remove it.
String commentKey = dataSnapshot.getKey();
// [START_EXCLUDE]
int commentIndex = mCommentIds.indexOf(commentKey);
if (commentIndex > -1) {
// Remove data from the list
mCommentIds.remove(commentIndex);
mComments.remove(commentIndex);
// Update the RecyclerView
notifyItemRemoved(commentIndex);
} else {
Log.w(TAG, "onChildRemoved:unknown_child:" + commentKey);
}
// [END_EXCLUDE]
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {
Log.d(TAG, "onChildMoved:" + dataSnapshot.getKey());
}
@Override
public void onCancelled(DatabaseError databaseError) {
Log.w(TAG, "postComments:onCancelled", databaseError.toException());
Toast.makeText(mContext, "Failed to load interventions.",
Toast.LENGTH_SHORT).show();
}
};
ref.addChildEventListener(childEventListener);
// [END child_event_listener_recycler]
// Store reference to listener so it can be removed on app stop
mChildEventListener = childEventListener;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View view = inflater.inflate(R.layout.item_view, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
MyModel comment = mComments.get(position);
holder.name_tv.setText(comment.name);
holder.details_tv.setText(comment.description);
}
@Override
public int getItemCount() {
return mComments.size();
}
public void cleanupListener() {
if (mChildEventListener != null) {
mDatabaseReference.removeEventListener(mChildEventListener);
}
}
public MyModel getItem(int position){
return mComments.get(position);
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView name_tv,details_tv;
View parent;
public ViewHolder(View rootView) {
super(rootView);
parent = rootView;
name_tv= (TextView) rootView.findViewById(R.id.name_tv);
details_tv = (TextView)rootView.findViewById(R.id.details_tv);
}
}
}