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Thread: Exception in thread "main" java.lang.NullPointerException

  1. #1
    Junior Member
    Join Date
    Dec 2013
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    Default Exception in thread "main" java.lang.NullPointerException

    Hi Guys,
    I am new to Java and what I am trying to do is to access an object from one method to another this is my code bellow:
    public class ClassRc1 extends ConfigClass {
        public static DefaultSelenium browser;
    	public static void main(String[] args) throws FileNotFoundException, IOException, InterruptedException{
    		public static void login() throws FileNotFoundException, IOException, InterruptedException
    		String url=ConfigClass.config.getProperty("url");
    		String username=ConfigClass.config.getProperty("username");
    		String password=ConfigClass.config.getProperty("password");
    	    Selenium browser= new DefaultSelenium("localhost",4444 , "*firefox", "http://"+url);
    		browser.type("//*[@id='email']", username);
    		browser.type("//*[@id='pass']", password);
    		public static void changephoto() throws FileNotFoundException, IOException, InterruptedException{
    			  browser.click("//*[@id='u_0_f']");	/* this line return null,ue of th how can i continue using the browser object from the previous method 	*/
    in method changephot i want to use the browser object but it seems the object it returns null value, how can i keep the value of the browser object from the login method and continue using it. thank you guys in advance.

  2. #2
    Super Moderator
    Join Date
    Jun 2013
    So. Maryland, USA
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    Thanked 697 Times in 679 Posts

    Default Re: Exception in thread "main" java.lang.NullPointerException

    Edit: Thank you for taking the time and making the minimal effort required to acquaint yourself with the forum, learning how to post code properly, and then applying it to your very first thread requesting assistance.

    In the main() method, change this line:

    Selenium browser= new DefaultSelenium("localhost",4444 , "*firefox", "http://"+url);


    browser= new DefaultSelenium("localhost",4444 , "*firefox", "http://"+url);

    The first version creates a new, local (to main()) variable called browser. The second version initializes the variable browser that was declared outside the main() method. The browser variable created by the second version is now available for use by the changePhoto() method.

    Further, I'll advise you to get rid of everything 'static' other than the main() method. Running the functionality of an entire program from a static main() method is the technique used by very early beginners from which they should rapidly evolve. If you haven't yet made that necessary evolutionary step, I'll suggest you back up a few chapters in whatever book you're using as a study guide in order to write more code that gives you the understanding, experience, and confidence needed to make that leap.

  3. #3
    Junior Member
    Join Date
    Dec 2013
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    Default Re: Exception in thread "main" java.lang.NullPointerException

    Thank you very Much Brannon for your help dude you rock! and regarding the static type of functions , i did try to get rid of everything static but when i call the function from the main static function, i get an error and it asks me to change the changephot method to static, and i can't work around it! thank you very much sir for your help again and i wish you a merry Christmas!

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