I am new to this java Selenium. I have 2 classes. 1 parent and 1 child. I have some methods in the parent class. I pass 2 of them to the child class. The problem is only 1 method (from the parent) executes and the 2nd failed. can you help me to understand why I am getting the error and how to resolve it please  : &quot;java.lang.NullPointerException&quot; Parent class : public class SignUp {  public WebDriver driver;      public void go(WebDriver driver)     {     driver.findElement(By.id(&quot;id_sign_up&quot;)).click();     }         @Test         public void signup(WebDriver driver)                  {             driver.findElement(By.linkText(&quot;I’m an advertiser&quot;)).click();         }                       public void FormSign (WebDriver driver)                          {                 driver.findElement(By.xpath(&quot;//span[@css='1']&quot;)).sendKeys(&quot;Miron&quot;);             }            } Child class : public class OpenBrowser extends SignUp{   @Test public void Start() throws InterruptedException {             System.setProperty(&quot;webdriver.chrome.driver&quot;, &quot;C:\\Program Files\\Selenium\\chromedriver.exe&quot;);     WebDriver driver = new ChromeDriver();     driver.get(&quot;https://account.admitad.com/en/sign_in/&quot;);     SignUp sg = new SignUp();     sg.go(driver);     //sg.signup(driver);      }  @Test public void miron () {     SignUp mi = new SignUp();     mi.signup(driver); }  Can someone please help me? Thanks in advance
What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
Can I possibly recover the Windows system partition that I deleted (100MB)? After moving to SSD I deleted the System Partition (100MB) from my previous drive, causing mass destruction.  I tried to delete the System Partition which windows 7 creates (on my previous disc as I moved to SSD) and when I tried to extend the main partition size to include the new Unallocated Space it asked me if I wanted to convert the disc to Dynamic.  I simply pressed yes and the partition simply disappeared into unallocated space. All of my family pictures / videos lost.  After reading an article on Microsoft they said to recreate the partition with the same exact size, so I tried to do that but it didn't work. I did not format the drive at all when I created partitions.  How can I possibly recover the partitions?  Thanks! How to run xrandr commands at startup in Ubuntu When should I create a new tag? How do I request a new tag if I don't have enough rep? PostgreSQL check bloating of a table How do I change file permissions on a FAT32 drive? How can I recursively delete all files of a specific extension in the current directory? How do I safely delete all files with a specific extension (e.g. .bak) from current directory and all subfolders using one command-line? Simply, I'm afraid to use rm since I used it wrong once and now I need advice. Why does this cloth go down past the top surface of the cube? I was following a , and the presenter said that he did not change the default options other than enabling self-collision and increasing the collision object's friction from 5 to 10. His looks like the first image below, but when I tried that, the cloth goes down past the top surface and stops at the bottom surface (second and third images below). Why is it so?   I had a previous problem with cloth, and it was due to the objects' small size. This time, I made sure that both the cloth and the cube are large enough. (Cloth=7.68*8.22*1.99m, cube = 7.68*7.68*0.897m)  The project file can be . When does System.gc() do something? change color of pgfplot bar plot I want to plot two bar plots next to each other. This works without a problem. However both use the first color defined in a pre or selfdefined colorseries. I tried to modify the color manually in the plot, but the color and fill definitions have no effect:  \documentclass[border=5mm]{standalone} \usepackage{pgfplots, pgfplotstable}  \begin{document}  \pgfplotstableread[header=false, col sep=comma]{  1, first item 5, second item }\datatable  \begin{tikzpicture}   \begin{axis}[             ,xbar     ,bar width=2ex, y=3ex     ,enlarge y limits={abs=0.75}     ,ytick={data} % (\empty,data,{coordinate list})     ,yticklabels from table={\datatable}{1}   ]   \addplot table [     ,red!20!black,fill=red!80!white,     y expr=-\coordindex, % Use negative coordinate index as y coordinate     x index=0 % Use first column as x coordinate   ] {\datatable};   \end{axis} \end{tikzpicture}  \end{document}   The plot is still in the default blue. How do the Azkaban escapees get their wands back? Sirius Black and a few Death Eaters escape Azkaban and seem to operate after that with their wands intact.  How come?  If a mere expulsion from Hogwarts entails wand destruction (as happened with Hagrid), shouldn't an Azkaban sentence entail the same?  And even if we imagine that the perceived impossibility of escape from Azkaban made it seem unnecessary to destroy the wand, this would apply to Sirius but not to Death Eaters.  PS: Two comments suggested that the escapees acquired new wands. It would be nice to have a more definitive answer than just a suggestion or a list of possibilities. Thanks.  PPS: Returning the personal property to a released prisoner is one thing, but the wand is a different matter: this is usually the tool of the crime, and I don't see how it can be argued that it should be returned and not destroyed. Again, Hagrid had his wand destroyed and he was not even sentenced to Azkaban.  PPPS: Maybe wand destruction is only done for non-fully-qualified wizards? I am trying to prove this binomial identity $\sum_{r=0}^n {r {n \choose r}} = n2^{n-1}$ but am not able to think something except induction,which is of-course not necessary (I think) here, so I am inquisitive to prove this in a more general way.  The left side of an identity occurs while solving another problem (concerning binomial theorem) so I am more interested in deriving the right side from the left side, else I have to remember it now onward.  EDIT: I am more interested in an algebraic proof rather than combinatorial argument or something involving calculus (however I liked  and  solution), hence I am removing the combinatorics tag. My trackpad is broken so I can tap-to-click but i cannot drag and drop. This is really a problem when it comes to doing certain things.   Does anyone know how to program a sticky key to turn a click into a click-select that can then be dragged about?   I can't resize my browser or open window and I can't drag applications into the folder when installing etc.  free solutions only please.  A mid 2009 macbook-pro 13". 2.53 Ghz Intel Core 2 Due.   Running os lion (grudgingly). I have 2 graphics cards on my laptop. One is IGP and another discrete.   I've written a shell script to to turn off the discrete graphics card.  How can I convert it to systemd script to run it at start-up? Probability of a 2 pair in poker robots meta not blocking indexing We have a staging version of our website to test changes on at trailheadpaddleshack.ca/staging1. This never appeared in search before. Recently the staging site has appeared on Google and is affecting our search results.  I'm trying to figure out how the pages got there and how to remove them. The pages have always had &lt;meta name="robots" content="noindex, nofollow"&gt; in the head.  I am kinda new at this but was under the impression this should prevent Google from showing my site in results. I am pretty sure the results appeared in google after I accidently copy pasted some codes from the staging site to the live site that contained links to pages on the staging site. If anyone can point me in the right direction to figure out what happened and prevent it from happening again would be much appreciated.  robots.txt looks like this:  User-agent: * Disallow: /calendar-2/action~posterboard/ Disallow: /calendar-2/action~agenda/ Disallow: /calendar-2/action~oneday/ Disallow: /calendar-2/action~month/ Disallow: /calendar-2/action~week/ Disallow: /calendar-2/action~stream/ #Begin Attracta SEO Tools Sitemap. Do not remove sitemap: http://cdn.attracta.com/sitemap/4035112.xml.gz #End Attracta SEO Tools Sitemap. Do not remove   I also tried adding an X-Robots-Tag header and submited the site to be re-crawled. Did that a few days ago and I still see no changes. Here are the HTTP headers according to "Fetch as Google":  HTTP/1.1 200 OK X-Robots-Tag: noindex,nofollow Vary: Accept-Encoding Transfer-Encoding: chunked Date: Sun, 24 May 2015 16:26:49 GMT Server: LiteSpeed Connection: close X-Pingback: http://trailheadpaddleshack.ca/staging1/xmlrpc.php Content-Type: text/html; charset=UTF-8 Link: &lt;http://trailheadpaddleshack.ca/staging1/?p=170&gt;; rel=shortlink   I am now faced with a bunch of results I need to remove from Google asap as they contain out of date information and are affecting our search results. Webmaster Tools has something for removal of a single URL but I am looking to remove the entire /staging1/ subfolder. Any tips? Prove $\mathbb{Z}_2 \times \mathbb{Z}_2$ is not isomorphic to $\mathbb{Z}_4$ Astrophotography picture with too much noise. How do I correct this in postprocessing? This is the Milky Way above Kakadu National Park, Australia, and my first try at astrophotography.    Thirty second exposure, f/4.0 at 17mm with ISO 12800 (!!) which in hindsight probably was way too high and resulted in a lot of noise. I also used Picasa to increase contrast, but I probably went a bit overboard there as well.  , I am looking for input on how to better postprocess this picture to reduce noise. How do I install Wi-Fi drivers for Realtek RTL8723DE device in Ubuntu 16.04?  lspci -v | grep -i network 02:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723 I am an Australian currently on a Netherlands working holiday visa that ends in May next year. I would like to know if when my visa ends I then get another 90 days just as a regular tourist visa as I would like to do some more travel within Europe when my visa ends before going home to Australia. Let $H$ be a subgroup of $G$ with $[G:H]=n$ and $G$ finite.  Let $G$ act on left cosets of $H$ by left multiplication.  Let $N$ be the kernel of the action.  Show that $[G:N]$ divides $n!$.  Ok so I have a theorem that says that if $G$ is simple then it embeds into $S_n$.  So if $G$ is simple than I'm done because $G$ divides $n!$ and thus $N$ divides $n!$ and hence $[G:N]$ divides $n!$.  Now I also know that $N$ is the largest normal subgroup of $G$ contained in $H$.  Thus if $G$ isn't simple then it contains some non-trivial normal subgroup $K$ and thus $K\cap H$ is normal in $H$ and by the 2nd Iso Theorem $H/K\cap H\cong KH/H$...    As you can see I'm not sure where to go from here. I was hoping to prove that $K\cap H$ wasn't trivial and thus that $N$ couldn't be trivial since it must contain $K\cap H$, but I'm not sure I can, and even if I could I'm not sure that would help me in showing that $[G:N]$ is small enough to divide $n!$.  Can anyone give some guidance?  Thanks.