当尝试从firebase数据库填充微调器时，空指针异常

Question

我试图从Firebase数据库中填充Android Studio项目的旋转器。然而，当尝试运行应用程序时，我遇到了一个空指针异常。谁能告诉我我错过了什么?

代码:

public void populateSpinner(){
DatabaseReference db = FirebaseDatabase.getInstance().getReference();
db.child("Collection").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
final List<String> collections = new ArrayList<String>();
for (DataSnapshot collectionSnapshot: dataSnapshot.getChildren()) {
String collectionName = collectionSnapshot.child("name ").getValue(String.class);
collections.add(collectionName);
}
Spinner areaSpinner = (Spinner) findViewById(R.id.collectionList);
ArrayAdapter<String> areasAdapter = new ArrayAdapter<String>(AddItem.this, android.R.layout.simple_spinner_item, collections);
areasAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
areaSpinner.setAdapter(areasAdapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}

链接到firebase数据库的图像[1]: https://i.stack.imgur.com/SCfSI.png

Answer 1

您的孩子name在那里有空间

改变

String collectionName = collectionSnapshot.child("name ").getValue(String.class);

String collectionName = collectionSnapshot.child("name").getValue(String.class);

请确保您的child与您的型号class相同。