Android studio--如何用mapView畫出多個點?

1.以MainActivity.class implements OnMapReadyCallback為背景，使用locaJSONS中的資料去繪製。

private List<LocaJSON> locaJSONS;
MapView mapView;
private GoogleMap mGoogleMap;
private static final String MAP_VIEW_BUNDLE_KEY = "MapViewBundleKey";
private int jlength;
private LatLng[] latLng;

2.onCreate中

    mapView = findViewById(R.id.mapView);
     Bundle mapViewBundle = null;

     if (savedInstanceState != null) {
         mapViewBundle = savedInstanceState.getBundle(MAP_VIEW_BUNDLE_KEY);
     }

     mapView.onCreate(mapViewBundle);

     mapView.getMapAsync(LocaDetail.this);   //初始化，自動執行onMapReady

3.若是要將繪圖實作在onclick中，記得要在資料取得後再行繪圖(初始化)，否則會出錯。

4.自動複寫的方法(必須使用)
@Override
public void onMapReady(GoogleMap googleMap) {     //相關功能設定
    mGoogleMap=googleMap;
    mGoogleMap.setMinZoomPreference(12);
    mGoogleMap.setIndoorEnabled(true);
    UiSettings uiSettings = mGoogleMap.getUiSettings();
    uiSettings.setIndoorLevelPickerEnabled(true);
    uiSettings.setMyLocationButtonEnabled(true);
    uiSettings.setMapToolbarEnabled(true);
    uiSettings.setCompassEnabled(true);
    uiSettings.setZoomControlsEnabled(true);

    drawMap(mGoogleMap);     //以下實作繪圖的程式。

}

5.private void drawMap(GoogleMap mGoogleMap) {       //參數必須為onMapReady中處理好的mGoogleMap
        double[][] jjss = new double[jlength][2];
        Log.d("資料數 ", String.valueOf(jlength));

        for(int i = 0 ; i < jlength ; i++) {
            LocaJSON jj = locaJSONS.get(i);

            double l_la = 0;double l_lo=0;
            try
            {
                NumberFormat ddf1= NumberFormat.getNumberInstance();        //將字串(locaJSONS的資料)轉為double型態
                ddf1.setMaximumFractionDigits(5);

                l_la =ddf1.parse(jj.getLatitude()).doubleValue();
                l_lo =ddf1.parse(jj.getLongitude()).doubleValue();
                jjss[i][0]=l_la;
                jjss[i][1]=l_lo;


            }
            catch (ParseException e) {
                e.printStackTrace();
            }

        }
        latLng = new LatLng[jlength];
        for(int i=0;i<jlength;i++){
            Log.d("LOCAddf ",i+" : "+jjss[i][0]+" : "+jjss[i][1]);

            latLng[i] = new LatLng(jjss[i][0], jjss[i][1]);           //位置資訊打包

            MarkerOptions markerOptions = new MarkerOptions().position(latLng[i]);
            mGoogleMap.addMarker(markerOptions);                  //加入繪製

        }

        mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng[0],18)); //鏡頭以第一點為主
    }

6.必須實作的生命週期相關方法
@Override
protected void onResume() {
    super.onResume();
    mapView.onResume();
}

@Override
protected void onPause() {
    mapView.onPause();
    super.onPause();
}

@Override
protected void onDestroy() {
    mapView.onDestroy();
    super.onDestroy();
}

@Override
public void onLowMemory() {
    super.onLowMemory();
    mapView.onLowMemory();
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    mapView.onSaveInstanceState(outState);
}

7.