java - Double click event not working- DataGrid - GWT -

i having issue implementing double click handler datagrid. have found solution posted on stack overflow should fix problem believe, however, can not figure out:

1. how implement it? 2. <t>? 

i getting various errors not understand. issue way add cellpreviewhandler (line 6)

errors (line 6 & 8)

-the type new cellpreviewevent.handler(){} must implement inherited abstract method cellpreviewevent.handler.oncellpreview(cellpreviewevent)

-the method oncellpreview(cellpreviewevent) of type new asyncallback(string[][]>(){} must override or implement supertype method

mycode:

public class datagrid extends widget{     timer singleclicktimer;     int clickcount = 0;     int clickdelay = 300; mydatatable = new datagrid<string[]>(result.length, resources, key_provider); mydatatable.addcellpreviewhandler(new handler<t>(){ @override public void oncellpreview(final cellpreviewevent<t> event) {     if (event.gettypeint(event.getnativeevent().gettype()) == event.onmouseover) {         handleonmouseover(event);     } else if (event.gettypeint(event.getnativeevent().gettype()) == event.onclick) {         clickcount++;         if (clickcount == 1) {             singleclicktimer = new timer() {                  @override                 public void run() {                     clickcount = 0;                     handleonclick(event);                 }             };             singleclicktimer.schedule(clickdelay);         } else if (clickcount == 2) {             singleclicktimer.cancel();             clickcount = 0;             handleondblclick(event);         }     } } }); private void handleonmouseover(cellpreviewevent<t> event) {     element cell = event.getnativeevent().geteventtarget().cast();     gwt.log("mouse on event"); }  private void handleonclick(cellpreviewevent<t> event) {     element cell = event.getnativeevent().geteventtarget().cast();     gwt.log("click event"); }  private void handleondblclick(cellpreviewevent<t> event) {     element cell = event.getnativeevent().geteventtarget().cast();                 gwt.log("double click event"); } 

link original solution: adding double click event in celltable cell - gwt

this not code (a better option extend datagrid class), if don't want change much, replace <t> <string[]>.