In Java, in order to call the webdriver first you will have to set the past and then will have to create an Instance for the webdriver.
So this way you can use the webdriver.
System.setProperty("webdriver.chrome.driver","C:\\Your\\path\\chromedriver.exe");\\set the path
WebDriver driver = new ChromeDriver();\\create an instance
Using the above two statement you are good to go.
You can take a look on this question also