Selenium WD NullPointerException while executing simple JS code

Question

Spent 1 day on finding the solution to the following problem:

Can't execute even simple js code using selenium WD. It always returns NullPointerException. Already read tonns of answers but still can't find the reason. The code below is the code after 1 day investigation (I just have tried everything):

WebDriver driver2;
JavascriptExecutor js = (JavascriptExecutor)driver2;
driver.get(baseUrl+ "/");
js.executeScript("return showAlert()");

Here is the original code that is not working as well:

    public class DPT_class {
      private WebDriver driver;

      @Before
      driver = new FirefoxDriver();
      JavascriptExecutor js = (JavascriptExecutor) driver;

      @Test
      //some testing code here
      driver.get(baseUrl+ "/");
      js.executeScript("return showAlert()");
}

the same thing for any other js code such as alert(document.title) with and without return and quotes. *baseUrl is predefined of course.

Thanks!

Agree with @Smit on this one: the example code given does not assign a value to driver2, in which case js will not have a value either. Your compiler should be complaining that you are using a value which isn't "definitely assigned". — rutter
– rutter, Commented Sep 26, 2013 at 22:38
I edited the original post. Unfortunately this thing doesn't help :( — dred17
– dred17, Commented Sep 27, 2013 at 11:27

ddavison · Accepted Answer · 2013-09-27 04:09:50Z

2

As @Smit says, and per your NullPointerException

You've never actually initialized your WebDriver object, and you're attemting to cast a null object, to JavaScriptExecutor.

Depending on what sort of browser you want to use, you are able to do..

WebDriver driver = new ChromeDriver();
WebDriver driver = new FirefoxDriver(); // etc...

Also, why are you attempting to use 2 driver objects? You should only have 1. Keep your object named driver.

answered Sep 27, 2013 at 4:09

ddavison

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1 Comment

dred17 Over a year ago

I edited the original post. Unfortunately this thing doesn't help :(

dred17 · Accepted Answer · 2013-09-27 12:06:07Z

0

Have changed

private WebDriver driver;
      driver = new FirefoxDriver();
      JavascriptExecutor js = (JavascriptExecutor) driver;

to

WebDriver driver = new FirefoxDriver();
  JavascriptExecutor js = (JavascriptExecutor) driver;

Have no idea why but it works now! Thanks a lot!

answered Sep 27, 2013 at 12:06

dred17

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