无论我如何尝试，Firebase 用户 ID 都是空的?

Question

我做了一个应用程序，可以让用户登录并在谷歌地图上设置标记，并且标记连接到属于设置它的用户的聊天室。

现在的问题是无论我如何尝试，我都无法在聊天活动和 MapFragment 中获取 uid，它一直显示空，我不知道有什么问题 以下是三项活动：

有人可以帮帮我吗~~

登录活动

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
auth = FirebaseAuth.getInstance();
if (auth.getCurrentUser() != null) {
startActivity(new Intent(LoginActivity.this, MainActivity.class));
finish();
}
//authenticate user
auth.signInWithEmailAndPassword(email, password)
.addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
// If sign in fails, display a message to the user. If sign in succeeds
// the auth state listener will be notified and logic to handle the
// signed in user can be handled in the listener.
if (!task.isSuccessful()) {
// there was an error
if (password.length() < 6) {
edUserid.setError("密碼太短，請輸入超過6個字元!");
} else {
Toast.makeText(LoginActivity.this, "登入失敗", Toast.LENGTH_LONG).show();
}
} else {
Toast.makeText(getApplicationContext(),"登入成功",Toast.LENGTH_LONG).show();
startActivity(new Intent(LoginActivity.this, MainActivity.class));
finish();
}
}
});
}

聊天活动

fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
EditText input = (EditText)findViewById(R.id.input);
// Read the input field and push a new instance
// of ChatMessage to the Firebase database
FirebaseDatabase.getInstance()
.getReference(CHAT_PATH)
.push()
.setValue(new ChatMessage(input.getText().toString(),
FirebaseAuth.getInstance()
.getCurrentUser()
.getDisplayName())
);
// Clear the input
input.setText("");
}
});
ListView listOfMessages = (ListView)findViewById(R.id.list_of_messages);
adapter = new FirebaseListAdapter<ChatMessage>(this, ChatMessage.class,
R.layout.message, FirebaseDatabase.getInstance().getReference(CHAT_PATH)) {
@Override
protected void populateView(View v, ChatMessage model, int position) {
// Get references to the views of message.xml
TextView messageText = (TextView)v.findViewById(R.id.message_text);
TextView messageUser = (TextView)v.findViewById(R.id.message_user);
TextView messageTime = (TextView)v.findViewById(R.id.message_time);
// Set their text
messageText.setText(model.getMessageText());
messageUser.setText(model.getMessageUser());
// Format the date before showing it
messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)",
model.getMessageTime()));
}
};
listOfMessages.setAdapter(adapter);
}
}

MapFragment(其中的一部分(

mFirebaseDatabase = FirebaseDatabase.getInstance();

mFirebaseRef = mFirebaseDatabase.getReference("Map/"+userUID);
mFirebaseRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
LatLng myLatLon = dataSnapshot.getValue(FirebaseMarker.class).toLatLng();
// stash the key in the title, for recall later
Marker myMarker = mgoogleMap.addMarker(new MarkerOptions()
.position(myLatLon).draggable(true).icon(BitmapDescriptorFactory.fromResource(R.drawable.seedloc2)).title(dataSnapshot.getKey()));
// cache the marker locally
markers.put(dataSnapshot.getKey(), myMarker);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
LatLng myLatLon = dataSnapshot.getValue(FirebaseMarker.class).toLatLng();
// Move markers on the map if changed on Firebase
Marker changedMarker = markers.get(dataSnapshot.getKey());
changedMarker.setPosition(myLatLon);
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
Marker deadMarker = markers.get(dataSnapshot.getKey());
deadMarker.remove();
markers.remove(dataSnapshot.getKey());
Log.v(TAG, "moved !" + dataSnapshot.getValue());

}
@Override
public void onCancelled(DatabaseError databaseError) {
Log.v(TAG, "canceled!" + databaseError.getMessage());
}
});
}
}
@Override
public void onMapReady(final GoogleMap googleMap) {
MapsInitializer.initialize(getContext());
mgoogleMap = googleMap;
googleMap.setOnInfoWindowClickListener(new GoogleMap.OnInfoWindowClickListener(){
@Override
public void onInfoWindowClick(Marker marker) {
Intent intent = new Intent(getActivity(),ChatActivity.class);
startActivity(intent);

}
});

Answer 1

如果有一个活动可以正确获取uid，正如你所说，则将uid的值保存到变量中，并将其存储到intent并在活动之间使用它。无需在每个活动中获取 uid。您只需要获得一次。

//FirstActivity
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
intent.putExtra("uid", uid);
startActivity(intent);

要在第二个活动中恢复 uid，请使用以下代码：

//SecondActivity
String uid = (String) getIntent().getExtras().get("uid");

如果您需要在整个应用程序中使用该uid，请使用共享首选项来存储它。

希望对您有所帮助。