java - Why can't I use the selenium.(etc...) library? -

when try use selenium. library perform commands, don't work. i've imported import com.thoughtworks.selenium.*; library java: can't find symbol error.

    selenium.open("http://google.com/");      string alllinks[]=selenium.getalllinks();     for(int i=0;i<alllinks.length;i++){          selenium.click(alllinks[i]);         thread.sleep(3000);