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[英]How to get pushed data out of child in userID child Firebase (Android)?
[英]How to get value from pushed data in Firebase?
在我的 firebase 中,我存儲了問題及其答案。 每個答案都有一個 id,它來自 push()。 但我無法顯示已回答問題的所有用戶的列表。 請幫忙。
這是代碼:
ListView listView;
ArrayList<String> answerers = new ArrayList<>();
ArrayAdapter arrayAdapter;
String askedBy, question, likes;
FirebaseAuth mAuth;
DatabaseReference databaseReference;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_answers);
listView = findViewById(R.id.answersListView);
Intent intent = getIntent();
askedBy = intent.getStringExtra("askedBy");
question = intent.getStringExtra("question");
likes = intent.getStringExtra("numberOfLikes");
mAuth = FirebaseAuth.getInstance();
databaseReference = FirebaseDatabase.getInstance().getReference();
databaseReference.child("questions").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if (snapshot.exists()){
for (DataSnapshot dataSnapshot : snapshot.getChildren()){
if (dataSnapshot.child("question").getValue().toString().equals(question) && dataSnapshot.child("askedBy").getValue().toString().equals(askedBy)
&& dataSnapshot.child("likes").getValue().toString().equals(likes)) {
dataSnapshot.child("answers").getRef().addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshots) {
if (snapshots.exists()){
for (DataSnapshot dataSnapshots : snapshots.getChildren()){
String id = dataSnapshot.getRef().push().getKey();
answerers.add(dataSnapshots.child(id).child("answeredBy").getValue().toString());
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
arrayAdapter = new ArrayAdapter<>(ViewAnswersActivity.this, android.R.layout.simple_list_item_1, answerers);
listView.setAdapter(arrayAdapter);
}
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Intent intent1 = new Intent(ViewAnswersActivity.this, AnswerActivity.class);
intent1.putExtra("askedBy", askedBy);
intent1.putExtra("answeredBy", answerers.get(i));
intent1.putExtra("question", question);
intent1.putExtra("numberOfLikes", likes);
startActivity(intent1);
}
});
}
當我運行該應用程序時,listView 為空,表示尚未存儲值。
嘗試在 onDataChange() 中設置適配器
@Override
public void onDataChange(@NonNull DataSnapshot snapshots) {
if (snapshots.exists()){
for (DataSnapshot dataSnapshots : snapshots.getChildren()){
String id = dataSnapshot.getRef().push().getKey();
answerers.add(dataSnapshots.child(id).child("answeredBy").getValue().toString());
}
arrayAdapter = new ArrayAdapter<> (ViewAnswersActivity.this, android.R.layout.simple_list_item_1, answerers);
listView.setAdapter(arrayAdapter);
}
}
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