public static void main(String[] args) throws IOException {     RbnRunner runner = new RbnRunner();     runner.run();  }  public void run() throws IOException {      System.setProperty("webdriver.chrome.driver", "/Users/me/samples/Adam_milford/src/chromedriver");      WebDriver driver = new ChromeDriver();   but when I want to init a headless selenium driver instead of Chrome driver, the code failes:  public static void main(String[] args) throws IOException {     WebDriver driver = new HtmlUnitDriver();   why is that?  Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/http/impl/conn/PoolingClientConnectionManager     at com.gargoylesoftware.htmlunit.HttpWebConnection.createHttpClient(HttpWebConnection.java:536)     at com.gargoylesoftware.htmlunit.HttpWebConnection.getHttpClient(HttpWebConnection.java:500)     at com.gargoylesoftware.htmlunit.HttpWebConnection.setUseInsecureSSL(HttpWebConnection.java:711)     at com.gargoylesoftware.htmlunit.WebClient.setUseInsecureSSL(WebClient.java:1096)     at org.openqa.selenium.htmlunit.HtmlUnitDriver.createWebClient(HtmlUnitDriver.java:263)     at org.openqa.selenium.htmlunit.HtmlUnitDriver.&lt;init&gt;(HtmlUnitDriver.java:129)     at org.openqa.selenium.htmlunit.HtmlUnitDriver.&lt;init&gt;(HtmlUnitDriver.java:172)     at org.openqa.selenium.htmlunit.HtmlUnitDriver.&lt;init&gt;(HtmlUnitDriver.java:168)     at RbnRunner.run(RbnRunner.java:40)     at RbnRunner.main(RbnRunner.java:28) Caused by: java.lang.ClassNotFoundException: org.apache.http.impl.conn.PoolingClientConnectionManager     at java.net.URLClassLoader.findClass(URLClassLoader.java:381)     at java.lang.ClassLoader.loadClass(ClassLoader.java:424)     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)     at java.lang.ClassLoader.loadClass(ClassLoader.java:357)     ... 10 more
I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this?
Is there any difference between like best and like the best? Is there a difference between these two sentences? Are they the same?   What color do you like the best? What color do you like best?   Is there a difference in their meaning? Can I use Stack Exchange logos on a t-shirt or other apparel? I happened to notice while on the Super User site that one user's picture shows him wearing a shirt with the Super User logo on it. Interested, I wanted to find out where he got it from. Looking through old questions on Meta, I found out that there used to be a shop.stackexchange.com site that sold Stack Exchange gear. Unfortunately, they no longer sell any merchandise.  Is there any site where I can purchase a Stack Exchange site shirt/hat/etc.? If not, could I create a shirt/hat/etc. myself with one of the sites' logos on it? If so, where can I locate the logos in their largest size? Finding real roots of negative numbers (for example, $\sqrt[3]{-8}$) I just made some minor edits to the text of .  I didn't edit the tags at all.  When I completed my edits, my edit showed as:    Now, I think those tags were present before I started my edit, and so were probably slipped in by the OP in their edit grace window.  I have no problem with that tagging, but I don't like seeing edits attributed to me that I didn't make.  So, what the heck? The polar of a convex body $C$ is defined as:  For a convex body $C$, its polar $C^*$ is given by $$C^* = \{x\in\mathbb{R}^n: \langle x,c\rangle \le 1, \forall c\in C\}$$  If I start with an orthonormal basis $(e_i)_1^n$, positive constants $(\alpha_j)_1^n &gt; 0$ and the ellipsoid $$\varepsilon = \left\{x\in\mathbb{R}^n: \sum\limits_{j=1}^n \frac{\langle x,e_j\rangle^2}{\alpha_j^2} \leq 1  \right\}$$ how do I show that its polar ellipsoid is $$\varepsilon^* = S_1 = \left\{y\in\mathbb{R}^n: \sum_{j=1}^n \alpha_j^2 \langle y,e_j\rangle^2 \le 1\right\}$$ Using the definition, I saw that $$\varepsilon^* = S_2 = \{z\in\mathbb{R}^n: \langle z,x\rangle \le 1, \text{for all }x\in \varepsilon\}$$ Also, $\langle z,x\rangle = \sum_i\langle z,e_i\rangle\langle x,e_i\rangle$ I used Cauchy Schwartz to do one side of the proof, i.e. $S_1\subseteq S_2$: $$\left(\sum_i\langle y,e_i\rangle\langle x,e_i\rangle\right)^2 \leq \left(\sum_i\alpha_i^2 \langle y,e_i\rangle^2\right)\left(\sum_i \frac{\langle x,e_i\rangle^2}{\alpha_i^2}\right) \le 1 \implies \langle y,x\rangle \le 1$$ I need help with the other direction, i.e. $S_2\subseteq S_1$. Which other inequality might help? Is it possible to do a multiline pattern match using sed, awk or grep? Take for example, I would like to get all the lines between { and }  So it should be able to match    1. {}  2. {.....}  3. {.....      .....}  Initially the question used &lt;p&gt; as an example. Edited the question to use { and}. What does the "private" modifier do? Considering "private" is the default access modifier for class Members, why is the keyword even needed? Anonymous questions and Avatars Some Stack Exchange sites allow to ask an anonymous question by specifying a one-time user name and an email which is "required, but never shown". However the Gravatar attached to the email is shown anyway. Anonymous users do not want their picture to appear - someone can find their identity via google image search or someone that knows them.  Example: open incognito window and : Is it possible to log back into a Pokemon Go account? So I had 20+ Pokemon on my account and today when I tapped on the app, it brought me back to the original screen when you first start playing. My friend who signed up tested using my username when she first started and my username was unavailable, meaning the account still exists. I don't have the password for the account, but I do have the email. So I wanted to know if it was possible to log back into an account? Have Google index different languages at the same URL instead of just the default (English) I have a multilingual PHP site. I have set English as the default language.  The language changes automatically according to the browser settings. If it is French, the site will be seen in French.  However in the Google search results, even if I have the browser in French, the English language appears in the results. How can I fix that?  To be clear I don't want to use subdomains or URLs like www.example.com/fr/. I would like it to work like Facebook. 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How to gracefully handle files that exceed PHP's `post_max_size`? I need help with this:  If a is an element of $\mathbb Z_n$ and $\gcd(a,n) &gt; 1$ , then a is not invertible.   First you show that if $a$ is an element of $\mathbb Z_n$ and $\gcd(a,n)&gt;1$, then there  is an element $b$ of $\mathbb Z_n$ and ($b$ is not equal to the zero element) from which $ab = 0$.   The second part I cant get. i.e. show if $b$ is not the zero element  and $ab=0$ then $a$ is not invertible. I have two partitions that I want to mount on startup: /dev/sda3   /mnt/devel  ext4    defaults    0   2 /dev/sda2   /mnt/excess ntfs    defaults    0   2  The ext4 partition mounts fine (owned by me, writable only by me), but the NTFS mounts owned by root with R\W permission for all. How to fix this? drwxr-xr-x  7 amanda amanda 4096 2012-03-14 19:07 devel drwxrwxrwx  1 root   root   4096 2012-03-14 22:38 excess Using Pigeonhole Principle to prove two numbers in a subset of $[2n]$ divide each other Let $n$ be greater or equal to $1$, and let $S$ be an $(n+1)$-subset of $[2n]$. Prove that there exist two numbers in $S$ such that one divides the other.   Any help is appreciated! How can I do unit testing in Unity? How to implement Unit Test at Unity3D.   I wonder if it would be possible to extend the Unity editor to have some sort of testing framework in it.    Is there any guideline to implement it? Any reference like book, blog? Any working example or project?