java - Android map : how to remove previous circle, 但保留新 map 吗？

Question

所以我想要围绕用户当前位置形成一个圆圈，但目前每次我移动时都会创建一个新圆圈，但旧圆圈仍然存在。这会导致 map 上一片困惑。

        LocationRequest locationRequest = LocationRequest.create();
        locationRequest.setInterval(2000);
        locationRequest.setFastestInterval(1000);
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        locationCallback = new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                super.onLocationResult(locationResult);
                if (locationResult == null) {
                    return;
                }

                mLastKnownLocation = locationResult.getLastLocation();
                checkLocation = mLastKnownLocation;

                    LatLng lastKnownLatLng = new LatLng(mLastKnownLocation.getLatitude(), mLastKnownLocation.getLongitude());

                    Circle mapCircle = mMap.addCircle(new CircleOptions()
                            .center(new LatLng(mLastKnownLocation.getLatitude(),mLastKnownLocation.getLongitude()))
                            .radius(20)
                            .strokeColor(Color.argb(200,0,64,122))
                            .strokeWidth(5)
                            .fillColor(Color.argb(100,82,189,236)));
                    mapCircle.setCenter(new LatLng(mLastKnownLocation.getLatitude(),mLastKnownLocation.getLongitude()));

HERE I CALCULATE SOME OTHER STUFF

//                mFusedLocationProviderClient.removeLocationUpdates(locationCallback);
            }
        };
        mFusedLocationProviderClient.requestLocationUpdates(locationRequest, locationCallback, null);

这就是我创建圆圈的方式。现在我尝试添加 mapCircle.remove() 但这导致根本没有得到圆圈。我怎样才能做到这一点。是的，我已经看过这个问题: Remove a circle from Android Google Maps API v2 without clearing map而且它似乎并没有解决我的问题。

Answer 1

您可以将本地 mapCircle 存储在 Activity 或 Fragment(您现在使用的是哪一个)中，然后在添加新的之前将其删除

class MyActivity extends Activity {
    Circle mapCircle = null;

    public someMethod() {
        // Inside location callback
        locationCallback = new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                super.onLocationResult(locationResult);
                if (locationResult == null) {
                    return;
                }

                mLastKnownLocation = locationResult.getLastLocation();
                checkLocation = mLastKnownLocation;

                LatLng lastKnownLatLng = new LatLng(mLastKnownLocation.getLatitude(), mLastKnownLocation.getLongitude());

                if (mapCircle != null) {
                    mapCircle.remove();
                }
                mapCircle = mMap.addCircle(new CircleOptions()
                        .center(new LatLng(mLastKnownLocation.getLatitude(),mLastKnownLocation.getLongitude()))
                        .radius(20)
                        .strokeColor(Color.argb(200,0,64,122))
                        .strokeWidth(5)
                        .fillColor(Color.argb(100,82,189,236)));
                mapCircle.setCenter(new LatLng(mLastKnownLocation.getLatitude(),mLastKnownLocation.getLongitude()));
            }
        }
    }
}