保存地图标记位置使用共享首选项单击地图

Question

当用户点击屏幕时，我正在尝试保存标记的位置，我已经按照有关如何使用共享首选项并检索它们的正确步骤进行操作。但是当我绘制一个位置并关闭并重新打开应用程序时。应用崩溃。

这是我的地图活动：

//Keys for Sharedpreferences
public static final String SHARED_PREF_NAME = "plot";
public static final String LONGTITUDE = "long";
public static final String LATITUDE = "lat";
public static final String PLOTTED= "plotted";
private boolean plotted= false;
  @Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
    LatLng philippines = new LatLng(13, 123);
    mMap.moveCamera(CameraUpdateFactory.newLatLng(philippines));
    mMap.animateCamera(CameraUpdateFactory.zoomTo(5.0f));
    if (ActivityCompat.checkSelfPermission(mapsPage.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(mapsPage.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    mMap.setMyLocationEnabled(true);
  mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
        @Override
        public void onMapClick(LatLng point) {
                mMap.clear();
                mMap.addMarker(new MarkerOptions().position(point).draggable(false));
                mMap.moveCamera(CameraUpdateFactory.newLatLng(point));
                String lat = Double.toString(point.latitude);
                String lon = Double.toString(point.longitude);
                SharedPreferences sharedPreferences = mapsPage.this.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE);
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putBoolean(LOGGEDIN_SHARED_PREF, true);
                editor.putString(LONGTITUDE, lon);
                editor.putString(LATITUDE, lat);
                editor.commit();
        }
    });
}
 @Override
protected void onResume() {
    super.onResume();
    SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE);
    checkedout = sharedPreferences.getBoolean(LOGGEDIN_SHARED_PREF, false);
    if(checkedout)
    {
        SharedPreferences sharedPreferencess = getSharedPreferences(mapsPage.SHARED_PREF_NAME, Context.MODE_PRIVATE);
        String lon = sharedPreferencess.getString(mapsPage.LONGTITUDE,"Not Available");
        String lat = sharedPreferencess.getString(mapsPage.LATITUDE,"Not Available");
        double lo = Double.parseDouble(lon);
        double la = Double.parseDouble(lat);
        LatLng resumedPosition = new LatLng(lo,la);
        mMap.clear();
        mMap.addMarker(new MarkerOptions().position(resumedPosition).draggable(false));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(resumedPosition));
    }
}

提前感谢您的任何帮助！ :D

Answer 1

看起来您正在尝试在onResume()上移动地图，但我想当 android 调用 onResume() 时地图还没有准备好。因此，为了解决此问题，我会将其移动到onMapReady()方法上。

//Keys for Sharedpreferences
public static final String SHARED_PREF_NAME = "plot";
public static final String LONGTITUDE = "long";
public static final String LATITUDE = "lat";
public static final String PLOTTED= "plotted";
private boolean plotted= false;
@Override
public void onMapReady(GoogleMap googleMap) {
  mMap = googleMap;
  mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
  LatLng philippines = new LatLng(13, 123);
  mMap.moveCamera(CameraUpdateFactory.newLatLng(philippines));
  mMap.animateCamera(CameraUpdateFactory.zoomTo(5.0f));
  if (ActivityCompat.checkSelfPermission(mapsPage.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(mapsPage.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
    return;
  }
  mMap.setMyLocationEnabled(true);
  mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
    @Override
    public void onMapClick(LatLng point) {
      mMap.clear();
      mMap.addMarker(new MarkerOptions().position(point).draggable(false));
      mMap.moveCamera(CameraUpdateFactory.newLatLng(point));
      String lat = Double.toString(point.latitude);
      String lon = Double.toString(point.longitude);
      SharedPreferences sharedPreferences = mapsPage.this.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE);
      SharedPreferences.Editor editor = sharedPreferences.edit();
      editor.putBoolean(LOGGEDIN_SHARED_PREF, true);
      editor.putString(LONGTITUDE, lon);
      editor.putString(LATITUDE, lat);
      editor.commit();
    }
  });
  SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE);
  checkedout = sharedPreferences.getBoolean(LOGGEDIN_SHARED_PREF, false);
  if(checkedout)
  {
    SharedPreferences sharedPreferencess = getSharedPreferences(mapsPage.SHARED_PREF_NAME, Context.MODE_PRIVATE);
    String lon = sharedPreferencess.getString(mapsPage.LONGTITUDE,"Not Available");
    String lat = sharedPreferencess.getString(mapsPage.LATITUDE,"Not Available");
    double lo = Double.parseDouble(lon);
    double la = Double.parseDouble(lat);
    LatLng resumedPosition = new LatLng(lo,la);
    mMap.clear();
    mMap.addMarker(new MarkerOptions().position(resumedPosition).draggable(false));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(resumedPosition));
  }
}
@Override
protected void onResume() {
  super.onResume();

}