我正在开发一个Android应用程序，其中我使用Firebase作为后端进行身份验证和存储数据。
我可以从Firebase数据库存储和检索位置，但无法在地图上显示标记。
代码如下：
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback
{
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
//Retrieve data from the firebase
final FirebaseDatabase database = FirebaseDatabase.getInstance();
final DatabaseReference myRef = database.getReference().child("users");
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot)
{
collectLocation((Map<String, Object>) dataSnapshot.getValue());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
private void collectLocation(Map<String, Object> users)
{
for (Map.Entry<String, Object> entry : users.entrySet())
{
//Get user map
Map singleUser = (Map) entry.getValue();
//Get phone field and append to list
locationData.add((String) singleUser.get("location"));
count[0]++;
}
System.out.println("Location: " + locationData.toString());
System.out.println("My count is: " + count[0]);
for(String loc : locationData)
{
System.out.println("LocationMMdm" + loc);
String[] Location = loc.split(",");
for(int i=0;i<2;i++)
{
System.out.println("LOcation " + i + " " + Location[i]);
if (i==0) {
lat = Double.parseDouble(Location[i]);
}
if (i==1){
log = Double.parseDouble(Location[i]);
}
}
System.out.println("lat: " + lat + " " + "log: " + log);
//mMap.addMarker(new MarkerOptions().position(new LatLng(loc.)).title("A"));
}
}
private void collectdriverInfo(Map<String, Object> users)
{
for (Map.Entry<String, Object> entry : users.entrySet())
{
//Get user map
Map singleUser = (Map) entry.getValue();
//Get phone field and append to list
DriverInfo.add((String) singleUser.get("driverInfo"));
}
System.out.println("Driver Information: " + DriverInfo.toString());
}
@Override
public void onMapReady(GoogleMap googleMap)
{
mMap = googleMap;
mMap.setMyLocationEnabled(true);
mMap.addMarker(new MarkerOptions().position(new LatLng(lat,log)).title("A"));
}
}
我已将全局声明的lat和log中的纬度和经度值存储起来。但我无法从onMapReady函数