title: Exception in thread "main" java.lang.IllegalStateException for using Selenium
body: <p>I m using Selenium to fill in web forms .I added the library<code>client-combined 3.0.0 beta 3</code> to the document .My firefox version should be most updated . However , it comes out error .How to fix ? Or using webdriver as Chrome better? </p>
  
  <pre><code> import org.openqa.selenium.By;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.firefox.FirefoxDriver;
  
  public class Selenium {
  
      /**
       * @param args the command line arguments
       */
      public static void main(String[] args) {
  
  
  
  WebDriver driver=new FirefoxDriver();
  
  driver.get("https://mail.google.com");
  driver.findElement(By.id("Email")).sendKeys("yourEmailId");
  driver.findElement(By.id("Passwd")).sendKeys("yourPassword");
  driver.findElement(By.id("signIn")).click();
  
  }
  
  }
  </code></pre>
  
  <blockquote>
    <p>Exception in thread "main" java.lang.IllegalStateException: The path to the driver executable must be set by the webdriver.gecko.driver system property; for more information, see <a href="https://github.com/mozilla/geckodriver" rel="nofollow">https://github.com/mozilla/geckodriver</a>. The latest version can be downloaded from <a href="https://github.com/mozilla/geckodriver/releases" rel="nofollow">https://github.com/mozilla/geckodriver/releases</a></p>
  </blockquote>