I found a similar error as mine on stackoverflow and added selenium webdriver jar files to the project using the below method :
right click on project--> goto build path--> configure build path--> click on "Add external jars"--> add selenium jar files from your local machine--> click ok--> now mouseover on WebDriver in your code--> click "import webdriver"--now run your code-->you will get rid of the exception.
However, I am still getting an error. Here's the error :
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
WebDriver cannot be resolved to a type
FirefoxDriver cannot be resolved to a type
This error happens when you use Eclipse as IDE and try to run code that doesn't even compile. Check your Problems view in Eclipse, and fix the compilation errors before executing the application.
even i got the the same error but then i realised that i missed 2 additional JAR files from Selenium 2.53.0.
selenium-java-2.53.0-srcs.jar
selenium-java-2.53.0.jar
these are not in the sub library " libs" in selenium 2.53.0 but listed separately in the same folder.
I had the same problem but then i came to know that i was missing a jar to add, this jar is not inside the lib folder you can find it immediately outside the lib folder: client-combined-3.0.1-nodeps.jar
I had the problem of WebDriver cannot be resolved to a type FirefoxDriver cannot be resolved to a type.I was using Selenium -java 3.0.1 jars.Also the jars client-combined-3.0.1-nodeps are required to to added .hence problem solved.
WebDriver3.0 will support the latest firefox also. but you have to set the properties for that
download "geckodriver.exe" file and you can try this.
System.setProperty("webdriver.firefox.marionette",
"E:\\SeleniumAutomation\\geckodriver-v0.9.0-win64\\geckodriver.exe");
driver = new FirefoxDriver();
driver.get("http://stackoverflow.com/");