I am learning about the Inner Class in Java, but i write this code, when i compile it, i got this error: Error:(84, 23) java: non-static variable this cannot be referenced from a static context.      public class Main {      class Outer {         private String string;          Outer(String s) {             this.string = s;         }          public Inner inner() {             return new Inner();         }          class Inner {             @Override             public String toString() {                 return string;             }         }     }      public static void main(String[] args) {         Outer outer = new Outer("yang");       //  System.out.println(outer.inner().toString());     } }   I have update the Inner Class to this, and it works.  public class Main {      static class Outer {         private String string;          Outer(String s) {             this.string = s;         }          public Inner inner() {             return new Inner();         }          class Inner {             @Override             public String toString() {                 return string;             }         }     }     public Outer outer(String s){         return new Outer(s);     }     public static void main(String[] args) {       //  Main main = new Main();         Outer outer = new Outer("YANG");         System.out.println(outer.inner().toString());     } }
What is the main difference between an inner class and a static nested class in Java? Does design / implementation play a role in choosing one of these?
Subsections as an enumerate I want to have subsections named all the same with a number behind it. The straight forward approach I came up with is this:   \section{User Stories} \subsection*{Userstory 1} This is story 1 \subsection*{Userstory 2} This is story 2   But I though isn't this possible as a list? So I have tried a few things but none worked. I have just learned the basics of LaTeX, and I want to try some more advanced tricks in LateX, but it won't work. I have tried this and some things very similar to this:   \section{User Stories} \begin{enumerate} [label=\subsection*{Userstory \arabic*}]     \item This is story 1     \item This is story 2 \end{enumerate}   Is this behaviour even possible to automatically? What is the best approach, for not typing the number and the title every time. Thanks in advance! Suppose that $X_1, \ldots, X_n \sim N(0,1)$ are independent random variables. I am interested in finding a constant C that satisfies:  $$ E\left[\max_{1\leq i\leq n}|X_i|\right] \leq C \sqrt{log\  n} $$  I know one method is to employ the moment generating function trick, then take logs of both sides. However, I was wondering if there exists a more direct method. thanks! Removing phone number from iMessage I'd like to remove my phone number from my iMessage account, but still have my phone enabled to receive messages sent to my email address (also used on iPad, Mac). Is there a way of doing this? I have an UTF-8, polish text in .tex file. When I open it with my LEd (LaTeX editor), it shows ok (all characters can be seen). But when I try to compile it, I get error:  Package inputenc Error: Keyboard character used is undefined (inputenc) in inputencoding `utf8'.   I have to copy the text, cut it and paste to Notepad++, change (not convert!) encoding from UTF8 to ANSI (the polish characters will be missed and replaces with some random characters). Than copy it again and paste to LEd (in that editor, characters display bad also). But now I can compile my pdf and in it, the encoding is right again.  Is there a way to set encoding in the way I will see characters in LEd propertly and I will be able to compile it and I will get good characters in pdf?  The begging of my code:  \documentclass[12pt]{report} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{graphicx} \usepackage{amsmath,amssymb,amsfonts} \usepackage{txfonts} How to activate bluetooth device for RTL8723DE? The wireless drivers for the RTL8723DE appeared for downloading and the module is now usable for Wi-Fi.   See   But the bluetooth part of it is yet not supported on Ubuntu. How this can be fixed?  lsusb shows  Bus 001 Device 003: ID 0bda:b009 Realtek Semiconductor Corp.    And usb-devices | awk '/0bda/' RS=  T:  Bus=01 Lev=02 Prnt=02 Port=03 Cnt=01 Dev#=  3 Spd=12  MxCh= 0 D:  Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs=  1 P:  Vendor=0bda ProdID=b009 Rev=02.00 S:  Manufacturer=Realtek S:  Product=802.11n WLAN Adapter S:  SerialNumber=00e04c000001 C:  #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=500mA I:  If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb I:  If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb Symmetric Inequality in $\mathbb{R}$ How can I calculate this limit? ideas? How can I calculate this limit? $$\lim_{n\rightarrow\infty} \frac{7^{\sqrt{n+1}-\sqrt{n}}\cdot(\frac{n+1}{2})!\cdot(\frac{n+1}{2})!}{(n+1)\cdot(\frac{n}{2})!\cdot(\frac{n}{2})!}$$ I don't have idea and I will be happy for help. What are all the correct answers to the Squirrel's questions, and what is the reward when I get them all correct? I encountered The Squirrel at "A tree."              |   |                                                                         |   |                     "   Hello, I'm The                        |             |                        Squirrel. I can                        |             |                      provide you candies,                     |             |                      and lots of things.                                    |                      I know how much you                                    |        _.-'''-,      love candies. But I                                    |      .'        `\     feel alone in this                                    |     /           /          forest.       "                         |        |    /      .--^_^                                                   |        |    |     /  C ,,\                                                           |    |    |   \  _.)                           ___                            |     \   |   /  \                   ____.----'.-'                            |      '-, \./ \)\)               .-' --  __.-'                   |            \        `-/   );/           ___/  - _.-'                        |             \_________''--'-'________.-' --    /                            |              -   --        -  -     -     __.-'                                              -    --    -     --   --  /                                                 _________________________.-'                                 He asks you some questions. What are the correct answers, and what is the reward for getting them correct? MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES) How to make itemize/enumerate/description environment robust to missing \item elements? Is there any way to make LaTeX tolerate empty itemize/enumerate (i.e. no \item)?  Specifically, I would welcome any package/elegant hack that would gracefully "cancel" a list if no elements are found (instead of firing up a Latex Error).  Before jumping to the obvious answer (which I expect would be something along the lines of "don't use itemize if you don't have items to put in" ;)) please consider my use-case:   I want to format remotely stored elements (say, bibliographic items), which I can only access as an XML file.  &lt;elems&gt;   &lt;bibelem&gt;&lt;title&gt;Cool result 1&lt;/title&gt;&lt;author&gt;joe&lt;/author&gt;&lt;/bibelem&gt;   &lt;bibelem&gt;&lt;title&gt;Cool result 2&lt;/title&gt;&lt;author&gt;jim&lt;/author&gt;&lt;/bibelem&gt; &lt;/elems&gt;  I have a python script that downloads/parses the XML and outputs its content in a file bib.tex as a list of Latex macros-decorated data  \BibElem{Cool result 1}{joe} \BibElem{Cool result 2}{jim}  Now, I want to grant the end-user complete control over the styling of her/his produced document, so the intended usage within Latex is something like  \documentclass{article} \begin{document}   \newcommand{\BibElem}[2]{\item {\em #1} by {#2}}   \begin{itemize}     \input{bib.tex}   \end{itemize} \end{document}    The rationale behind this design choice is that the user should be restricted as little as possible in her/his styling choices. For instance, the user may either want to display the bibelems within a list as shown in the example, or may prefer a fancy-formatted tabular. On the other hand, the user should design the latex document once, and should be able to run it regardless of the amount of data produced by the source.  Therefore, the python script cannot make any assumption regarding the context in which its latex product will be included, and it should be up to the user to deal with empty bibliographies, i.e. with empty lists. How could one possibly do that?  Update: Werner proposed a nice solution that redefines the list environment to make Latex oblivious of the fact he is currently in a list. However, this only seems to work if the empty list is the last list in the document, as revealed by the following mwa:    \documentclass{article} \makeatletter \newenvironment{myitemize}   {\itemize}   {\@newlistfalse\enditemize} \makeatother \begin{document}   % Empty Itemize   \begin{myitemize}   \end{myitemize}   % Next non-nested itemize environment (can be itemize/enumerate/description)    \begin{myitemize}     \item Arghh!   \end{myitemize} \end{document} What are the positives and negatives of periodic DFT codes that don't use plane-wave basis sets? Most periodic density functional theory (DFT) codes use plane-wave basis sets in conjunction with three-dimensional periodic boundary conditions. In contrast, for molecular systems of finite size, Gaussian basis sets are often used. The former are quite efficient for periodic systems, but more expensive methods such as hybrid functionals become intractable for large system sizes. The latter is well-suited for finite clusters but rarely is appropriate for periodic systems.   uses a mixed Gaussian and plane-wave approach (GAPW) for periodic systems.  models periodic systems using atom-centered Gaussian functions.  expresses wavefunctions in real space, avoiding explicit basis sets.  What are some positives and negatives of these alternate approaches, when compared to more conventional periodic DFT packages? Why does Beamer's table of contents items link to the second slide in a section? When I include a table of contents in a Beamer slide show, each section entry in the TOC ends up linking to the second slide in that section. I would have expected it to link to the first slide. What am I doing wrong?:  \documentclass{beamer}  \begin{document} \begin{frame}{Test TOC}   \tableofcontents \end{frame}  \section{Section 1}  \begin{frame}   \frametitle{Test 1} \end{frame}  \begin{frame}   \frametitle{Test 2} \end{frame}  \end{document}   Just to clarify: when I click Section 1 in the TOC, it takes me to the slide Test 2.  UPDATE: I am actually not sure if it takes me to slide Test 2. When I click the link, the viewer (Evince and Okular) displays most of Test 2, but with a tiny strip of the slide Test 1 visible at the top of the window. I suspect that the viewer may treat the link as pointing to the very bottom of slide Test 1 and then aligns that with the top of the window. Could this be the explanation? Is there a way to determine which features / variables of the dataset are the most important / dominant within a k-means cluster solution? How to block any app from being installed? My mom has an android tablet and she doesn't even know what a site is, her e-mail, or even the password of her facebook account. She's an average user. The internet is facebook in her eyes. She has no need for apps or anything, it's just, only, precisely facebook. All is facebook.  How can I completely disable installing apps in android so they can't be installed in any way or form, I mean, not by URL, not by clicking, not by app store, not even by another program. Just disable the entire thing altogether.  Doesn't need to be safe, have locks, passwords etc. I'm not trying to secure the device from intruders, attackers or robbers, I'm trying to secure it from its very own user.  Please help. I just had to remove two anti-virus apps that were opening adware pages when she tried to open facebook lite, and that's obviously a no-go, apps which she "had not installed." Clearly there's some voodoo going on here for them to just popup, or maybe she just did it unknowingly, but none of that's relevant. How can you just disable installs so this couldn't ever happen again? Does eating infected flesh have an effect? I don't remember what actually happends when people eat infected flesh. I have in mind :  Gareth and the cannibals eating bitten Bob's leg in . It seems that the cannibals survive for a while after eating Bob's flesh and they seem OK.  The Saviors eating pigs that ate walkers in . We don't know for how long this process has been on, but  has his routine and looks used to doing that. Can we assume that Saviors are eating infected pig flesh for a while now ?  Does it have negative effect in long term ? Clarifying question on meaning of derivative of a linear transformation In my analysis class, my professor (and the textbook) reference the fact that $\mathbf{D}T(\bar{x}) = T$ for any $\bar{x} \in \mathbb{R}^n$ where $T \in \mathcal{L}(\mathbb{R}^n,\mathbb{R}^n) $. I'm wondering about the precise meaning of this statement. Is it that the differential of any linear transformation is also linear? Or is that the differential of any linear transformation is itself (and therefore also linear)? The second seems confusing to me because the derivative of a function is often not itself. For example, $f(x) = 2x$ is a linear transformation but $f'(x) = 2 \ne 2x$ for all $x \in \mathbb{R}$. How can I install Broadcom Wireless Adapter BCM4352 802.11ac PCID [14e4:43b1] (rev 03) on fresh install of Ubuntu 14.10 (Utopic Unicorn)? I have a brand new Dell XPS 15. I   dual boot it with Windows 8.1 and  Ubuntu 14.10  The Wireless Network Adapter is Broadcom BCM4352 802.11ac with PCID [14e4:43b1] (rev 03).  The 4352 is not included in the list for installation via bcmwl-kernal-source file. I tried this anyway, but the Terminal command led to the file starting to install, but then stopping. Sometimes I get a permission denied error message.  As a result of reading and trying all advice from forums I have decided to completely reinstall Ubuntu 14.10. I doubt my particular Broadcom Wireless Card has no support on Ubuntu 14.10?    Edit:  The advice of Chili555 worked. I now have working wifi using Broadcom Wireless Adapter BCM4352 802.11ac PCID [14e4:43b1] (rev 03) The integral $\int_0^\infty \dfrac{x \sin(x)}{x^2+1} dx$ How to calculate: $$\int_0^\infty \frac{x \sin(x)}{x^2+1} dx$$ I thought I should find the integral on the path  $[-R,R] \cup \{Re^{i \phi} : 0 \leq \phi \leq \pi\}$.  I can easily take the residue in $i$ $$  Res_{z=i} \frac{x \sin(x)}{x^2+1}  \quad = \quad \frac{i (e^{ii}-e^{-ii})}{2i}  \quad = \quad \frac{i(\frac1e-e)}{2i} \quad = \quad \frac1{2e}-\frac e2 $$ I know that the integral on $[-R,R]$ will get nearby the real value of $ \frac12\int_0^\infty \frac{x \sin(x)}{x^2+1} dx$. That means that I'm done if I show that the integral on the other part of the path will be small, here is an attempt to do so:  $$ \left|\frac{x \sin(x)}{x^2+1} \right|  \quad \leq \quad  R \cdot \frac{|\sin x|}{R^2-1} $$ I could rewrite $\sin x$ but it becomes nasty. Can you help me with this? How to hook into the CPT's title placeholder? How can I upload files asynchronously with jQuery? I would like to upload a file asynchronously with jQuery.     $(document).ready(function () {     $("#uploadbutton").click(function () {         var filename = $("#file").val();          $.ajax({             type: "POST",             url: "addFile.do",             enctype: 'multipart/form-data',             data: {                 file: filename             },             success: function () {                 alert("Data Uploaded: ");             }         });     }); }); &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js"&gt;&lt;/script&gt; &lt;span&gt;File&lt;/span&gt; &lt;input type="file" id="file" name="file" size="10"/&gt; &lt;input id="uploadbutton" type="button" value="Upload"/&gt;     Instead of the file being uploaded, I am only getting the filename. What can I do to fix this problem?