如何读取firebase中的数据列表？

Question

     private void updateUI(boolean state,String uid){
    if(state) {
        Toast.makeText(this, "SUCCESSFULL", Toast.LENGTH_SHORT).show();

        if(uid != null) {
            Log.d(tag,"uid is"+uid);
            database= FirebaseDatabase.getInstance();
            action_taken_booking = database.getReference().child("Bae").child("Booking list").child(uid).child("Action taken");
            action_taken_blocked = database.getReference().child("Bae/Blocked list/" + uid + "/Action taken");
            times_blocked = database.getReference().child("Bae/Blocked list/" + uid + "/Times blocked");
            Log.d(tag,action_taken_booking.getParent().toString());
            action_taken_booking.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    booking_action_taken =  dataSnapshot.getValue(boolean.class);
                    Log.d(tag,"booking_action_taken"+booking_action_taken);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

            action_taken_blocked.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    blcoked_action = (Long) dataSnapshot.getValue();
                    Log.d(tag,"Blocked action"+blcoked_action);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
            times_blocked.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    blocked_times = (Long) dataSnapshot.getValue();
                    Log.d(tag,"TimesBlocked"+blocked_times);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
            Log.d(tag,"Upddate UI"+blcoked_action+"  "+ blocked_times);
            blocked_action_taken = (blocked_times - blcoked_action) == 0;
            if (booking_action_taken) {
                Intent nextActivity = new Intent(SigninActivity.this, HotelActivity.class);
                nextActivity.putExtra("uid", uid);
                startActivity(nextActivity);
            }
        }
    }
}

我的代码没有从数据库中读取任何内容。事实上，代码没有进入onDataChange方法。此代码是在登录活动中编写的。我使用共享偏好设置使用了自动登录功能。由于有几种方法可以签名，因此我使用了更新ui方法来进行所需的活动。