我需要一個函數來從 FirebaseFirestore 獲取所有數據/注釋。如何讓這個函數在返回之前等待所有數據？我認為我創(chuàng)建的這個函數在主線程中不起作用，并且在從 firebase 獲取數據之前返回 public static ArrayList<NoteFB> getNotes() { FirebaseFirestore db = FirebaseFirestore.getInstance(); final String TAG = "FB Adapter"; final ArrayList<NoteFB> doFBs = new ArrayList<>(); db.collection("notesItem") .get() .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() { @Override public void onComplete(@NonNull Task<QuerySnapshot> task) { if (task.isSuccessful()) { for (QueryDocumentSnapshot document : task.getResult()) { Log.d(TAG, document.getId() + " => " + document.getData()); doFBs.add(document.toObject(NoteFB.class)); } } else { Log.w(TAG, "Error getting documents.", task.getException()); } } }); return doFBs; } MyFBAdapter myFBAdapter = new MyFBAdapter(ShowActivity.this, FBAdapter.getNotes()); rvContacts.setAdapter(myFBAdapter);此代碼返回一個空的 ArrayList，它創(chuàng)建一個空的 recyclerview。
2 回答
叮當貓咪
TA貢獻1776條經驗 獲得超12個贊
最近出現了很多這樣的問題。我不久前就找到了解決方案：使用任務 API。
public static ArrayList<NoteFB> getNotes() {
FirebaseFirestore db = FirebaseFirestore.getInstance();
final String TAG = "FB Adapter";
final ArrayList<NoteFB> doFBs = new ArrayList<>();
try {
Task<QuerySnapshot> taskResult = Tasks.await(db.collection("notesItem").get(), 2, TimeUnit.SECONDS)
for (QueryDocumentSnapshot document : task.getResult()) {
Log.d(TAG, document.getId() + " => " + document.getData());
doFBs.add(document.toObject(NoteFB.class));
}
} catch(Exception e) {
Log.w(TAG, "Error getting documents.", e.localizedString());
}
return doFBs
}
如果我犯了任何語法錯誤，請原諒我，我的 Java 有點生疏了。
確保您在主線程之外調用此代碼，否則它將崩潰。
烙印99
TA貢獻1829條經驗 獲得超13個贊
您可以為此使用接口
public interface NoteDataInterface {
void onCompleted(ArrayList<NoteFB> listNotes);
}
更改您的方法以使用接口：
public static void getNotes(NoteDataInterface noteDataInterface) {
FirebaseFirestore db = FirebaseFirestore.getInstance();
final String TAG = "FB Adapter";
final ArrayList<NoteFB> doFBs = new ArrayList<>();
db.collection("notesItem")
.get()
.addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (QueryDocumentSnapshot document : task.getResult()) {
Log.d(TAG, document.getId() + " => " + document.getData());
doFBs.add(document.toObject(NoteFB.class));
}
} else {
Log.w(TAG, "Error getting documents.", task.getException());
}
noteDataInterface.onCompleted(doFBs);
}
});
}
然后調用你的方法：
getNoteData(new NoteDataInterface() {
@Override
public void onCompleted(ArrayList<NoteFB> listNotes) {
Log.e("listNotes>>",listNotes.size()+"");
}
});
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