更新用户的位置 [英] Updating user's location

问题描述

我有一些麻烦与谷歌地图。我需要在地图上显示用户的位置，然后对其进行更新。我使用的是默认的标记。然而，我的方式code当前设置，它的每一个OnLocationChanged调用时增加了一个新的标记。我希望它只是更新一个标志或删除旧的，因为它增加了一个新的当前位置。这里的code：

 公共类GoogleMapActivity扩展FragmentActivity实现LocationListener的{
双longitude_user，latitude_user;
koordinate_user的LatLng;
GoogleMap的supportMap;
字符串名称，地址，类型;
BitmapDesc​​riptor BDF;
私人的LocationManager的LocationManager;
私人字符串供应商;
地点位置;
标记标记;保护无效的onCreate（捆绑savedInstanceState）{
    // TODO自动生成方法存根
    super.onCreate（savedInstanceState）;
    的setContentView（R.layout.activity_googlemaps）;    SupportMapFragment FM =（SupportMapFragment）getSupportFragmentManager（）findFragmentById（R.id.map）。
    supportMap = fm.getMap（）;    的LocationManager =（的LocationManager）getSystemService（Context.LOCATION_SERVICE）;    标准标准=新标准（）;
    供应商= locationManager.GPS_PROVIDER;
    如果（！locationManager.isProviderEnabled（LocationManager.GPS_PROVIDER））{
        供应商= locationManager.NETWORK_PROVIDER;
    }
    如果（供应商== NULL）{
        供应商= locationManager.getBestProvider（标准，FALSE）;
    }    如果（位置！= NULL）{
        的System.out.println（提供者+提供商+已被选择。）;
        onLocationChanged（位置）;
      }其他{
        Log.i（测试，位置不可用）;
      }    位置= locationManager.getLastKnownLocation（供应商）;}/ *请求更新在启动* /
  @覆盖
  保护无效onResume（）{
    super.onResume（）;
    locationManager.requestLocationUpdates（供应商，1000，10，本）;
    //Log.i(\"test，提供者：+提供商）;
  }  / *删除LocationListener的更新时，活动暂停* /
  @覆盖
  保护无效的onPause（）{
    super.onPause（）;
    locationManager.removeUpdates（本）;
  }  @覆盖
  公共无效onLocationChanged（地点）{
    latitude_user = location.getLatitude（）;
    longitude_user = location.getLongitude（）;    如果（latitude_user = NULL＆放大器;！＆安培;！longitude_user = NULL）{
        koordinate_user =新的经纬度（latitude_user，longitude_user）;
        标记= supportMap.addMarker（新的MarkerOptions（）
                .POSITION（koordinate_user））;
    }  }  @覆盖
  公共无效onStatusChanged（字符串提供商，INT地位，捆绑演员）{
    // TODO自动生成方法存根  }  @覆盖
  公共无效onProviderEnabled（字符串提供商）{
    Toast.makeText（这一点，已启用新的供应商+供应商，
        Toast.LENGTH_SHORT）.show（）;  }  @覆盖
  公共无效onProviderDisabled（字符串提供商）{
    Toast.makeText（这一点，残疾人提供+供应商，
        Toast.LENGTH_SHORT）.show（）;
  }
}
 

解决方案

更​​新此你的 onLocationChanged 法

  @覆盖
公共无效onLocationChanged（地点）{
latitude_user = location.getLatitude（）;
longitude_user = location.getLongitude（）;如果（latitude_user = NULL＆放大器;！＆安培;！longitude_user = NULL）{
    如果（标记！= NULL）
        marker.remove（）;
    koordinate_user =新的经纬度（latitude_user，longitude_user）;
    标记= supportMap.addMarker（新的MarkerOptions（）
            .POSITION（koordinate_user））;
}}
 

希望这是你想要的。

I'm having some trouble with Google Maps. I need to display user's location on the map and then update it. I'm using a default marker. However, the way my code is currently set up, it adds a new marker every time OnLocationChanged is called. I want it to just update that one marker or remove old one as it adds a new one with current location. Here's the code:

public class GoogleMapActivity extends FragmentActivity implements LocationListener {
Double longitude_user, latitude_user;
LatLng koordinate_user;
GoogleMap supportMap;
String title, address, type;
BitmapDescriptor bdf;
private LocationManager locationManager;
private String provider;
Location location;
Marker marker;

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_googlemaps);

    SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
    supportMap = fm.getMap();

    locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

    Criteria criteria = new Criteria();
    provider = locationManager.GPS_PROVIDER;
    if(!locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
        provider = locationManager.NETWORK_PROVIDER;
    }


    if (provider == null){
        provider = locationManager.getBestProvider(criteria, false);
    }

    if (location != null) {
        System.out.println("Provider " + provider + " has been selected.");
        onLocationChanged(location);
      } else {
        Log.i("test", "Location not available");
      }

    location = locationManager.getLastKnownLocation(provider);

}

/* Request updates at startup */
  @Override
  protected void onResume() {
    super.onResume();
    locationManager.requestLocationUpdates(provider, 1000, 10, this);
    //Log.i("test", "Provider: " + provider);
  }

  /* Remove the locationlistener updates when Activity is paused */
  @Override
  protected void onPause() {
    super.onPause();
    locationManager.removeUpdates(this);
  }

  @Override
  public void onLocationChanged(Location location) {
    latitude_user = location.getLatitude();
    longitude_user = location.getLongitude();

    if (latitude_user != null && longitude_user != null) {
        koordinate_user = new LatLng(latitude_user, longitude_user);
        marker = supportMap.addMarker(new MarkerOptions()
                .position(koordinate_user));
    }

  }

  @Override
  public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

  }

  @Override
  public void onProviderEnabled(String provider) {
    Toast.makeText(this, "Enabled new provider " + provider,
        Toast.LENGTH_SHORT).show();

  }

  @Override
  public void onProviderDisabled(String provider) {
    Toast.makeText(this, "Disabled provider " + provider,
        Toast.LENGTH_SHORT).show();
  }
}

解决方案

Update your onLocationChanged method by this

@Override
public void onLocationChanged(Location location) {
latitude_user = location.getLatitude();
longitude_user = location.getLongitude();

if (latitude_user != null && longitude_user != null) {
    if(marker != null)
        marker.remove();
    koordinate_user = new LatLng(latitude_user, longitude_user);
    marker = supportMap.addMarker(new MarkerOptions()
            .position(koordinate_user));
}

}

Hope this is what you wanted.

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