Question

我有这样的json数据：

[
 {
  "id": 1,
  "name": "name",
  "login": "login",
  "lat": "43.854891",
  "lng": "73.536660"
 },
 {
  "id": 2,
  "name": "name",
  "login": "login",
  "lat": "53.954891",
  "lng": "73.536660"
 }
]

我从json获取所有数据并显示它们，但是当位置发生变化时，我无法在不删除旧位置的情况下显示新数据。还有一个当前位置，显示和删除旧位置。这是我的代码：

    private static final String REQUEST_URL = "http://192.168.1.103:8080/";

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);

    checkPermission();
    buildGoogleApiClient();
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    LocationSearchTask locationSearchTask = new LocationSearchTask();
    locationSearchTask.execute(REQUEST_URL);

}


@Override
public void onLocationChanged(Location location) {
    Log.i(TAG, location.toString());
    latitude = location.getLatitude();
    longitude = location.getLongitude();
    LatLng latLng = new LatLng(latitude, longitude);
    if (currentMarker != null) {
        currentMarker.remove();
    }
    displayLocation(latLng, 15f, location);
    updateOtherLocations();
}  
public void updateOtherLocations() {
    LocationSearchTask locationSearchTask = new LocationSearchTask();

    locationSearchTask.execute(REQUEST_URL);
}

class LocationSearchTask extends AsyncTask<String, Void, List<User>> {

  @Override
    protected List<User> doInBackground(String... urls) {
        try {
            if (urls.length < 1 || urls[0] == null) {
                return null;
            }
            List<User> result = QueryData.fetchUsersData(urls[0]);
            return result;
        } catch (Exception e) {
            Toast.makeText(MapsActivity.this, "Error: " + e.getMessage(), Toast.LENGTH_SHORT).show();
            return null;
        }
    }

    @Override
    protected void onPostExecute(List<User> users) {
        try {

            for (User user : users) {
                LatLng position = new LatLng(user.getLat(), user.getLng());
                // add marker
                otherMarkers = mMap.addMarker(new MarkerOptions()
                        .position(position)
                        .title(user.getFirstName())
                        .icon(bitmapDescriptorFromVector(getApplicationContext(), R.mipmap.ic_navigation))
                        .snippet(user.getEmail()));
            }

        } catch (Exception e) {
            Toast.makeText(MapsActivity.this, "Sorry other locations are unavailable! Error: " + e.getMessage(), Toast.LENGTH_SHORT).show();
        }
    }

我如何删除** otherLocations **并显示新位置？我知道这是一个糟糕的代码，如果你能告诉我还有什么值得改变的话。提前谢谢。

Answer 1

您可以使用mMap.clear()从地图中删除所有标记。如果您想更新标记位置（如果是当前标记），请保留以前添加的标记，然后更改为marker.setPosition(new LatLng(50,5));

Answer 2

标记上有一个现有字段可以使它们可见或不可见请参见标记文档中的可见

如何从JSON数据中删除地图上的标记？

2 个答案: