java - How to create a Singleton method which adds a Google Map marker? -

how create method can add marker singleton. every time try, the map null , marker null. doesn't give me nullpointer exception 0.

how make them not null marker can show on map after use call controller.getinstance().adaugaruta(mapsactivity.this); on main activity , use map<> objectmap method. problem here, on singleton...i think, because on main activity receive map<> objectmap key entered value 0 because marker null.

public class controller { googlemap mmap; private static controller instance;  private controller() { }  public static controller getinstance() {     if (instance == null) {         instance = new controller();     }     return instance; }  public map<string, list<marker>> adaugaruta(showtherute theroute) {      map<string, list<marker>> objectmap = new hashmap<>();     marker mae = null;      icongenerator iconita = new icongenerator(mapsactivity.getappcontext());     iconita.setcontentpadding(5, -5, 5, -5);     iconita.setrotation(-270);     iconita.setcontentrotation(270);     bitmap iconbit = iconita.makeicon("this icon.");      if (mmap != null) {   here problem --->mae = mmap.addmarker(new markeroptions().icon(bitmapdescriptorfactory.frombitmap(iconbit)).position(new latlng(46.762035, 23.597659)).anchor(0f, 0.5f));         mae.isvisible();     }     list<marker> marker1 = new arraylist<>();     marker1.add(mae);     objectmap.put("marker1", marker1);     theroute.gettherute(objectmap);      return objectmap; } 

the thing if remove if (mmap != null) gives nullpointerexception. use interface can use data map<> objectmap in mapsactivity implements interface. works, key , value 0 because marker null.

in code didn't define >>>> mmap <<<<<

of course should give null pointer exception !!!

define map somewhere, can this:

googlemap mmap; private static controller instance;  private controller() { }  public static controller getinstance(googlemap map) {     if (instance == null) {         instance = new controller();         instance.mmap=map;     }     return instance; } 

and later in other function :

public map<string, list<marker>> adaugaruta(showtherute theroute) {     ...     if (instance.mmap != null) {         mae = instance.mmap.addmarker(new  markeroptions().icon(bitmapdescriptorfactory.frombitmap(iconbit)).position(new latlng(46.762035, 23.597659)).anchor(0f, 0.5f));         mae.isvisible();     }   ..     return objectmap; }