android - i dont know how to get the position of the img that i click so i can pass it to next acitvity -

my grid view working okay , displays image sdcard.when long press image contextual task box open.one of option view(to view in full screen).i dont know how id or postion of selected image can pass activity open in fullscreen.

public class mainactivity extends activity {

public class imageadapter extends baseadapter {      private context mcontext;     arraylist<string> itemlist = new arraylist<string>();      public imageadapter(context c) {         mcontext = c;        }      void add(string path){         itemlist.add(path);      }      @override     public int getcount() {         return itemlist.size();     }      @override     public object getitem(int position) {         // todo auto-generated method stub         return itemlist.get(position);     }      @override     public long getitemid(int position) {         // todo auto-generated method stub         return 0;     }      @override     public view getview(int position, view convertview, viewgroup parent) {         imageview imageview;         if (convertview == null) {  // if it's not recycled, initialize attributes             imageview = new imageview(mcontext);             imageview.setlayoutparams(new gridview.layoutparams(165, 165));             imageview.setscaletype(imageview.scaletype.center_crop);             //imageview.setpadding(8, 8, 8, 8);         } else {             imageview = (imageview) convertview;         }          bitmap bm = decodesampledbitmapfromuri(itemlist.get(position), 250, 250);          imageview.setimagebitmap(bm);         return imageview;     }      public bitmap decodesampledbitmapfromuri(string path, int reqwidth, int reqheight) {          bitmap bm = null;         // first decode injustdecodebounds=true check dimensions         final bitmapfactory.options options = new bitmapfactory.options();         options.injustdecodebounds = true;         bitmapfactory.decodefile(path, options);          // calculate insamplesize         options.insamplesize = calculateinsamplesize(options, reqwidth, reqheight);          // decode bitmap insamplesize set         options.injustdecodebounds = false;         bm = bitmapfactory.decodefile(path, options);           return bm;           }      public int calculateinsamplesize(          bitmapfactory.options options, int reqwidth, int reqheight) {         // raw height , width of image         final int height = options.outheight;         final int width = options.outwidth;         int insamplesize = 1;          if (height > reqheight || width > reqwidth) {             if (width > height) {                 insamplesize = math.round((float)height / (float)reqheight);                 } else {                 insamplesize = math.round((float)width / (float)reqwidth);                   }            }          return insamplesize;         }  }  imageadapter myimageadapter;  @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      gridview gridview = (gridview) findviewbyid(r.id.gridview);     myimageadapter = new imageadapter(this);     gridview.setadapter(myimageadapter);      string externalstoragedirectorypath = environment             .getexternalstoragedirectory()             .getabsolutepath();      string targetpath = externalstoragedirectorypath ;      toast.maketext(getapplicationcontext(), targetpath, toast.length_long).show();     file targetdirector = new file(targetpath);      file[] files = targetdirector.listfiles();     (file file : files){         myimageadapter.add(file.getabsolutepath());      }      registerforcontextmenu(gridview); }      @override       public void oncreatecontextmenu(contextmenu menu, view v,contextmenuinfo menuinfo) {       super.oncreatecontextmenu(menu, v, menuinfo);           menu.setheadertitle("context menu");           menu.add(0, v.getid(), 0, "view");           menu.add(0, v.getid(), 0, "details");         menu.add(0, v.getid(), 0, "delete");      }        @override       public boolean oncontextitemselected(menuitem item) {           if(item.gettitle()=="view"){function1(item.getitemid());}           else if(item.gettitle()=="details"){function2(item.getitemid());}           else if(item.gettitle()=="delete"){function3(item.getitemid());}           else {return false;}       return true;       }        public void function1(int id){            // sending image id fullscreenactivity         intent = new intent(getapplicationcontext(), fullimageactivity.class);         // here problem want position or id of clicked strong textimage , pass other activity can view full screen          i.putextra("id", position);         startactivity(i);         toast.maketext(this, "function 1 called", toast.length_short).show();       }   

}`

@override     public void oncreate(bundle savedinstancestate) {    super.oncreate(savedinstancestate);  setcontentview(r.layout.activity_main);  gridview gridview = (gridview) findviewbyid(r.id.gridview);  myimageadapter = new imageadapter(this); gridview.setadapter(myimageadapter); gridview.setonitemclicklistener(new onitemclicklistener() {      @override       public void onitemclick(adapterview<?> parent, view view, int position,       long id) {      system.out.println("position"+position);     }    }    });    string externalstoragedirectorypath = environment         .getexternalstoragedirectory()         .getabsolutepath();  string targetpath = externalstoragedirectorypath ;  toast.maketext(getapplicationcontext(), targetpath, toast.length_long).show(); file targetdirector = new file(targetpath);  file[] files = targetdirector.listfiles(); (file file : files){     myimageadapter.add(file.getabsolutepath());  }  registerforcontextmenu(gridview);  }