Your question title is much more general than your requirements, so I will answer this in a way that I think will benefit those viewing this question and hopefully meet your requirements in perhaps a different way.
If you are not showing directions in the context of a map already being a loaded fragment and something having been done to show directions over the map (which is probably similar to what the OP is doing), it's easier and I believe standard to do this with an Intent
.
This launches a map pathing activity (through a separate application - where the app launched depends on the user's compatible apps, which by default is Google Maps) that plots directions from the origin address (String originAddress
) to the
destination address (String destinationAddress
) via roadways:
// Build the URI query string.
String uriPath = "https://www.google.com/maps/dir/";
// Format parameters according to documentation at:
// https://developers.google.com/maps/documentation/directions/intro
String uriParams =
"?api=1" +
"&origin=" + originAddress.replace(" ", "+")
.replace(",", "") +
"&destination=" + destinationAddress.replace(" ", "+")
.replace(",", "") +
"&travelmode=driving";
Uri queryURI = Uri.parse(uriPath + uriParams);
// Open the map.
Intent intent = new Intent(Intent.ACTION_VIEW, queryURI);
startActivity(activity, intent, null);
(Where activity
is simply the currently active Activity
- obtained through whatever means are appropriate in the current programming context).
The following code gets an address String
from a LatLng
object (which must then be processed for the URI query String
as above):
/**
* Retrieves an address `String` from a `LatLng` object.
*/
private void getAddressFromLocation(
final StringBuilder address, final LatLng latlng) {
// Create the URI query String.
String uriPath =
"https://maps.googleapis.com/maps/api/geocode/json";
String uriParams =
"?latlng=" + String.format("%f,%f",
latlng.latitude, latlng.longitude) +
"&key=" + GOOGLE_MAPS_WEB_API_KEY;
String uriString = uriPath + uriParams;
// Issue the query using the Volley library for networking.
RequestFuture<JSONObject> future = RequestFuture.newFuture();
JSONObject response = null;
// Required for JsonObjectRequest, but not important here.
Map<String, String> jsonParams = new HashMap<String, String>();
JsonObjectRequest request =
new JsonObjectRequest(Request.Method.POST,
uriString,
new JSONObject(jsonParams),
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
if (response != null) {
String resultString =
response.getJSONArray("results")
.getJSONObject(0)
.getString("formatted_address");
// Assumes `address` was empty.
address.append(resultString);
} // end of if
// No response was received.
} catch (JSONException e) {
// Most likely, an assumption about the JSON
// structure was invalid.
e.printStackTrace();
}
} // end of `onResponse()`
}, // end of `new Response.Listener<JSONObject>()`
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e(LOG_TAG, "Error occurred ", error);
}
});
// Add the request to the request queue.
// `VolleyRequestQueue` is a singleton containing
// an instance of a Volley `RequestQueue`.
VolleyRequestQueue.getInstance(activity)
.addToRequestQueue(request);
}
This request is asynchronous, but it can be made synchronous.
You will need to call toString()
on the actual parameter passed to address
to obtain originAddress
.