How to take snapshot in Selenium WebDriver using java.

import java.io.File;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.apache.commons.io.FileUtils;
import org.openqa.selenium.OutputType;
import org.openqa.selenium.TakesScreenshot;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;


public class Takesnapshot {

    public static void main(String[] args) throws IOException {

        // Intialize Web driver
        WebDriver driver = new FirefoxDriver();
        //Maximizw window
        driver.manage().window().maximize();
         //Launch website
        driver.get("http://www.yahoo.com");
        // wait for page loads
      driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);

        // Takes snapshort
        File scrFile = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);
        // Save screen shot desired location
        FileUtils.copyFile(scrFile, new File("screenshot.png"));

        // close wbe driver
        driver.quit();

    }

}