我正在尝试读取我的云Firestore中的数据,并将其放入名为“ urlList”的数组中。 arrayList在onComplete中,如果我将数组记录到那里,它就可以工作(它充满了它应该具有的数据)。每当我在onComplete外部记录arrayList时,该数组为空。该问题似乎与onCompletelistener有关,但我找不到出什么问题/如何避免该问题。我添加了数字5和6的日志以检查问题所在,并且onCreate的日志中确实看到了5,但没有看到6
public static ArrayList<String> urlList = new ArrayList<String>();
public static ArrayList<String> groupList = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_middel_scherm);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
ConstraintLayout layout = (ConstraintLayout) findViewById(R.id.imageLayout);
setSupportActionBar(toolbar);
db = FirebaseFirestore.getInstance();
mAuth = FirebaseAuth.getInstance();
CurrentUser = FirebaseAuth.getInstance().getCurrentUser().getUid();
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() == null) {
startActivity(new Intent(MiddelScherm.this, LoginScherm.class));
}
}
};
ivImage = (ImageView) findViewById(R.id.ivImage);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
SelectImage();
}
});
databaseDownload();
Log.d(TAG, "egregergegre");
Log.d(TAG, String.valueOf(urlList));
Log.d(TAG, "egregergegre");
showEachImage(layout);
}
public void showEachImage(ConstraintLayout layout) {
for (String element: urlList) {
ImageView image = new ImageView(this);
image.setLayoutParams(new android.view.ViewGroup.LayoutParams(80,60));
image.setMaxHeight(20);
image.setMaxWidth(20);
Picasso.get().load(element).into(image);
layout.addView(image);
}
}
public void databaseDownload() {
urlList.add("5");
db.collection("user").document(CurrentUser).collection("meta-data")
.get()
.addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
urlList.add("6");
for (DocumentSnapshot document : task.getResult()) {
String imageValue = document.getString("URL");
urlList.add(imageValue);
Log.d(TAG, String.valueOf(urlList));
}
} else {
Log.w(TAG, "Error getting documents.", task.getException());
}
}
});
db.collection("user").document(CurrentUser).collection("Group")
.get()
.addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (DocumentSnapshot document : task.getResult()) {
String groupValue = document.getString("Group");
groupList.add(groupValue);
Log.d(TAG, String.valueOf(groupList));
}
} else {
Log.w(TAG, "Error getting documents.", task.getException());
}
}
});
}
我什至试图将公共无效的showEachImage(ConstraintLayout layout)放在onCompletelistener内,但在“ this”处出现了以下错误:ImageView image = new ImageView(this):所以我放弃了该结构好
public void databaseDownload() {
urlList.add("5");
db.collection("user").document(CurrentUser).collection("meta-data")
.get()
.addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
urlList.add("6");
for (DocumentSnapshot document : task.getResult()) {
String imageValue = document.getString("URL");
ImageView image = new ImageView(this);
image.setLayoutParams(new
android.view.ViewGroup.LayoutParams(80,60));
image.setMaxHeight(20);
image.setMaxWidth(20);
Picasso.get().load(imageValue).into(image);
layout.addView(image);
Log.d(TAG, String.valueOf(urlList));
}
} else {
Log.w(TAG, "Error getting documents.", task.getException());
}
}
});
db.collection("user").document(CurrentUser).collection("Group")
.get()
.addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (DocumentSnapshot document : task.getResult()) {
String groupValue = document.getString("Group");
groupList.add(groupValue);
Log.d(TAG, String.valueOf(groupList));
}
} else {
Log.w(TAG, "Error getting documents.", task.getException());
}
}
});
}
答案 0 :(得分:0)
我认为与ImageView发生暗恋的原因是“ this”是onComplete方法中的OnCompleteListener类。
答案 1 :(得分:0)
您添加OnCompleteListener
的原因是get()
启动了异步 Task
,当查询完成。
onComplete()
方法立即返回 ,这意味着查询尚未完成,因此get()
方法将看不到任何数据。
任何需要数据的代码都应该在onCreate()
方法中执行。