android - 在 android 的谷歌地图上每 10 秒绘制一条折线

Question

我制作了一个应用程序，一旦按下开始按钮，每 10 秒就会获取用户的位置，并从旧位置到新位置绘制多段线，直到按下停止按钮。现在的问题是当折线代码在运行函数中时， map 上没有画线。但是如果我将该代码放在运行函数之外，它工作正常(就像当我重新按下开始按钮时我得到折线)但我不想每次都按下按钮，我希望那条线是通过计时器自行绘制。

这是我的代码

    track_record.setOnClickListener(new View.OnClickListener() {
                                            @Override
                                            public void onClick(View v) {
                                                Toast.makeText(getApplication(), "Your Tracking is started now", Toast.LENGTH_SHORT).show();
                                                ///////*************************************////////
                                                // create class object
                                                gps = new GPSTracker(MapsActivity.this);
                                                timer.scheduleAtFixedRate(new TimerTask() {

                                                    @SuppressLint("DefaultLocale")
                                                    @TargetApi(Build.VERSION_CODES.GINGERBREAD)
                                                    @Override

                                                    public void run() {
                                                        runOnUiThread(new Runnable() {
                                                            @Override
                                                            public void run() {

                                                                LatLng current =   new LatLng(latitude = gps.getLatitude(),longitude = gps.getLongitude());

                                                                if (begin == 0) {
                                                               fixedBegin = current;

                                                                    // create marker
                                                                    MarkerOptions marker = new MarkerOptions().position(fixedBegin).title("Begin ");

                                                                    // Changing the color babyyy
                                                                  marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
                                                                    // adding marker
                                                                mMap.addMarker(marker);


                                                                    // Not working here, but should be

                                                                    if(Flag==0)  //when the first update comes, we have no previous points,hence this
                                                                    {
                                                                        prev=current;
                                                                        Flag=1;
                                                                    }
                                                                    CameraUpdate update = CameraUpdateFactory.newLatLngZoom(current, 16);
                                                                    mMap.animateCamera(update);
                                                                    mMap.addPolyline((new PolylineOptions())
                                                                            .add(prev, current).width(6).color(Color.BLUE)
                                                                            .visible(true));
                                                                    prev=current;
                                                                    current = null;

                                                              }
                                                                begin++;

                                                                Log.i("OK", "lat------ " + latitude);
                                                                Log.i("OK", "lng-------- " + longitude);

                                                                arrLat.add(latitude);
                                                                arrLng.add(longitude);

                                                                //////////// TRYING ///////////
                                                                // And it Worked here

/*
                                                                if(Flag==0)  //when the first update comes, we have no previous points,hence this
                                                                {
                                                                    prev=current;
                                                                    Flag=1;
                                                                }
                                                                CameraUpdate update = CameraUpdateFactory.newLatLngZoom(current, 16);
                                                                mMap.animateCamera(update);
                                                                mMap.addPolyline((new PolylineOptions())
                                                                        .add(prev, current).width(6).color(Color.BLUE)
                                                                        .visible(true));
                                                                prev=current;
                                                                current = null;
*/


                                                            }
                                                        });


                                                    }
                                                }, 0, TIME_INTERVAL);


                                                // check if GPS enabled
                                                if (gps.canGetLocation()) {

                                                    latitude = gps.getLatitude();
                                                    longitude = gps.getLongitude();
                                                    String longlat = String.valueOf(latitude) + ":" + String.valueOf(longitude);
                                                    cordsList.add(longlat);
                                                    // \n is for new line
                                                    Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
                                                } else {
                                                    Toast.makeText(getApplicationContext(), "Sorry cant get location", Toast.LENGTH_LONG).show();
                                                    // can't get location
                                                    // GPS or Network is not enabled
                                                    // Ask user to enable GPS/network in settings
                                                    // gps.showSettingsAlert();
                                                }

                                                Log.i("Finall", "Location-> " + cordsList.toString());

                                            }
                                        }
        );

Answer 1

您可以为此目的使用处理程序。

类变量。

Handler m_handler;
Runnable m_handlerTask ;
int t=0;

使用延迟 10 秒的处理程序来使用经纬度绘制折线

m_handler = new Handler();
m_handlerTask = new Runnable()
{
@Override 
public void run() { 
if(t<listPoint.size()-1)
{     
LatLng src = listPoint.get(t);
LatLng dest = listPoint.get(t + 1);
Polyline line = mMap.addPolyline(new PolylineOptions()
    .add(new LatLng(src.latitude, src.longitude),
    new LatLng(dest.latitude,dest.longitude))                                       
    .width(2).color(Color.BLUE).geodesic(true)); 
    t++;
    }
    else
    {
   m_handler.removeCallbacks(m_handlerTask);
    } 
   m_handler.postDelayed(m_handlerTask, 10000);    
    }
};
m_handlerTask.run();