package test2;  public class NewJFrame extends javax.swing.JFrame {      private static void valueGen() {         String x = jTextField1.getText();         System.out.println(x);     }      public NewJFrame() {         initComponents();     }      private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {         jTextField1.setText("Hello");     }      public static void main(String args[]) {         valueGen();          java.awt.EventQueue.invokeLater(new Runnable() {             public void run() {                 new NewJFrame().setVisible(true);             }         });     }      private javax.swing.JButton jButton1;     private javax.swing.JTextField jTextField1; }   I have a program as shown above.  I need to access the value of jTextField1 from the function valueGen(). But I get the error:  non-static variable cannot be referenced from static context   What should I do in order to access the value of jTextField1 from valueGen()?
The very common beginner mistake is when you try to use a class property "statically" without making an instance of that class. It leaves you with the mentioned error message:     You can either make the non static method static or make an instance of that class to use its properties.   Why? I am not asking for solutions. I would be grateful to know what is the reason behind it. The very core reason!  private java.util.List&lt;String&gt; someMethod(){     /* Some Code */     return someList;             }  public static void main(String[] strArgs){                // The following statement causes the error. You know why..     java.util.List&lt;String&gt; someList = someMethod();          }
Short story where rain only on one side of the house gives away fake world? In the mid-90s I read a short story about a guy freaking out at his wife and therapist because as they were leaving the house to go on a train trip to New York City, he went back inside to grab something and noticed that out the back window it was raining, while out the front door it was clear and sunny.  This confirmed his existing paranoia that everything in his world was fake, and everyone he knew was either a robot or an actor, participating in a massive effort to fool him and keep him from remembering who he really was.  He eventually calms down and agrees to go on the trip. The story ends      with a twist where the wife and therapist have a conversation something like, that was a close one, he almost remembered. Now strike the house set and assemble the New York set.   Can anyone identify this story? It was probably in a magazine or anthology, either sci-fi or speculative fiction. How to explain dropout regularization in simple terms? I know that the compiler will sometimes initialize memory with certain patterns such as 0xCD and 0xDD.  What I want to know is when and why this happens.  When  Is this specific to the compiler used?  Do malloc/new and free/delete work in the same way with regard to this?  Is it platform specific?  Will it occur on other operating systems, such as Linux or VxWorks?  Why  My understanding is this only occurs in Win32 debug configuration, and it is used to detect memory overruns and to help the compiler catch exceptions.  Can you give any practical examples as to how this initialization is useful?  I remember reading something (maybe in Code Complete 2) saying that it is good to initialize memory to a known pattern when allocating it, and certain patterns will trigger interrupts in Win32 which will result in exceptions showing in the debugger.  How portable is this? What is wrong with using inline functions? While it would be very convenient to use inline functions at some situations,  Are there any drawbacks with inline functions?  Conclusion:  Apparently, There is nothing wrong with using inline functions.  But it is worth noting the following points!   Overuse of inlining can actually make programs slower. Depending on a function's size, inlining it can cause the code size to increase or decrease. Inlining a very small accessor function will usually decrease code size while inlining a very large function can dramatically increase code size. On modern processors smaller code usually runs faster due to better use of the instruction cache.  The speed benefits of inline functions tend to diminish as the function grows in size. At some point the overhead of the function call becomes small compared to the execution of the function body, and the benefit is lost  There are few situations where an inline function may not work:   For a function returning values; if a return statement exists. For a function not returning any values; if a loop, switch or goto statement exists.  If a function is recursive.   The __inline keyword causes a function to be inlined only if you specify the optimize option. If optimize is specified, whether or not __inline is honored depends on the setting of the inline optimizer option. By default, the inline option is in effect whenever the optimizer is run. If you specify optimize , you must also specify the noinline option if you want the __inline keyword to be ignored. How to hide a folder in sdcard in android ArcGIS Serious Application Error I'm a complete novice to GIS and just began an Introductory course. I am having an issue when I try to access the Symbology tab on a layer. Specifically, when I click on the 'Categories' field and 'Unique Values' subfield, ArcMap crashes and comes up with a report window to send to ESRI. The message is      ArcGIS for Desktop has encountered a serious application error and is   unable to continue.   What could be the problem? jQuery serialize does not register checkboxes When I analyze my variables in two separate (univariate) logistic regression models, I get the following:  Predictor 1:    B= 1.049,    SE=.352,    Exp(B)=2.85,    95% CI=(1.43, 5.69),    p=.003    Constant:    B=-0.434,    SE=.217,    Exp(B)=0.65,                            p=.046  Predictor 2:    B= 1.379,    SE=.386,    Exp(B)=3.97,    95% CI=(1.86, 8.47),    p&lt;.001    Constant:    B=-0.447,    SE=.205,    Exp(B)=0.64,                            p=.029   but when I enter them into a single multiple logistic regression model, I get:  Predictor 1:    B= 0.556,    SE=.406,    Exp(B)=1.74,    95% CI=(0.79, 3.86),    p=.171 Predictor 2:    B= 1.094,    SE=.436,    Exp(B)=2.99,    95% CI=(1.27, 7.02),    p=.012    Constant:    B=-0.574,    SE=.227,    Exp(B)=0.56,                            p=.012   Both predictors are dichotomous (categorical). I have checked for multicollinearity.  I am not sure if I have given enough info, but I cannot understand why predictor 1 has gone from being significant to non-significant and why the odds ratios are so different in the multiple regression model. Can anyone provide a basic explanation of what is going on? I've added many PPAs using the add-apt-repository command. Is there a simple way to remove these PPAs? I've checked in /etc/apt/sources.list for the appropriate deb lines but they aren't there.   This is on a server system so a command line solution would be great! How can we recover the Newtonian gravitational potential from the metric of general relativity? The Newtonian description of gravity can be formulated in terms of a potential function $\phi$ whose partial derivatives give the acceleration:  $$\frac{d^2\vec{x}}{dt^2}=\vec{g}=-\vec{\nabla}\phi(x)=\left(\frac{\partial\phi}{\partial x}\hat{x}+\frac{\partial\phi}{\partial y}\hat{y}+\frac{\partial\phi}{\partial z}\hat{z}\right)$$  However, in general relativity, we describe gravity by means of the metric. This description is radically different from the Newtonian one, and I don't see how we can recover the latter from the former. Could someone explain how we can obtain the Newtonian potential from general relativity, starting from the metric $g_{\mu\nu}$? I'm including \usepackage{hyperref} so that each instance of \ref (as well as each page number in the index and the table of contents) automatically links to that page.  When I'm viewing the document (in ) and I click a link, I jump to the linked page.  Is there any easy way to go "back" to where I was before I clicked the link?  (And is the answer any different when using Adobe Acrobat reader?) When to use a GAM vs GLM I realize this may be a potentially broad question, but I was wondering whether there are assumptions that indicate the use of a GAM (Generalized additive model) over a GLM (Generalized linear model)? Someone recently told me that GAMs should only be used when I assume the data structure to be &quot;additive&quot;, i.e. I expect additions of x to predict y. Another person pointed out that a GAM does a different type of regression analysis than a GLM, and that a GLM is preferred when linearity can be assumed. In the past I have been using a GAM for ecological data, e.g.:  continuous time-series when the data did not have a linear shape I had multiple x to predict my y that I thought to have some nonlinear interaction that I could visualize using &quot;surface plots&quot; together with a statistical test  I obviously don't have a great understanding of what a GAM does different than a GLM. I believe it's a valid statistical test, (and I see an increase in the use GAMs, at least in ecological journals), but I need to know better when its use is indicated over other regression analyses. Password protecting a page I'm trying to password protect a page but it doesn't seem to be working. I've set the password for the page but when you navigate to it it just loads up like normal and doesn't ask for any passwords.  This is the loop I have on my page:  &lt;?php /**  * @package WordPress  * @subpackage Default_Theme  * Template Name: Page  */  get_header(); ?&gt;  &lt;?php global $post; if ( post_password_required( $post ) ) { ?&gt;  &lt;?php $fields = get_acf(); ?&gt;  &lt;script type="text/javascript"&gt;  (function() {   window.onload = function() {   ...  }} )  &lt;/script&gt;  &lt;div id="map"&gt;&lt;/div&gt;  &lt;?php } else { ?&gt;     Not passworded        &lt;?php if (have_posts()) : ?&gt;         &lt;?php while (have_posts()) : the_post(); ?&gt;          &lt;?php endwhile; ?&gt;     &lt;?php endif; ?&gt;         &lt;?      } // Page isn't password-protected     ?&gt; &lt;?php get_footer(); ?&gt;   I want to password protect everything within the page.  UPDATE:  I have custom content on the page so if possible I need to be able to wrap some code around it all.  Update: "What was best" vs "what was the best"? Do both have the same meaning? Or they are subtly different? Example sentence:  What was (the) best? To go left or right, up or down?   it says that both are exactly the same. But I wonder if that's really the case. Jumping in an elevator? Set spawn point for a specific player I made a server and me and one of my friends want to do a prank on another friend, because he stole all my enchanted diamond armor.  The Prank  I want to set a player's spawn point in a pit of lava, how would I do this without affecting anyone else's spawn point? Cloning a Non-Standard Svn Repository with Git-Svn I'm relatively new to Git, but I've found it so easy to work with at home that I'd like to use it at work where our projects are stored in Svn repositories. Unfortunately, the repositories are slightly non-standard and I'm having trouble getting them cloned. Sure, they all have trunk, branches/ and tags/, but branches/ and tags/ have subdirectories before hitting the real project directories:  trunk/ branches/maintenance/release1 branches/maintenance/release2 ... branches/development/feature1 branches/development/feature2 ... tags/build/build1 tags/build/build2 ... tags/release/release1 tags/release/release2   After cloning:  $ git svn clone -s --prefix=svn/ https://mydomain.com/svnproject $ git branch -r   development   development@1340   maintenance   maintenance@1340   tags/build   tags/build@1340   tags/release   tags/release@1340   trunk   trunk@1340    I get none of the actual project branches or tags. I actually need to be able to work on the trunk, one maintenance branch and one development branch. I've tried this approach in addition to several hacks at modifying the config, but nothing is working for me.  Is there any way I can get the key components of my non-standard Svn project into a local git repository so that I can easily move between them?  Many thanks.  UPDATE: I should add that I can't do a wholesale switch to Git (yet). There are other team members involved and an international presence. The logistics of the transition are more than I'm willing to undertake until I'm much more comfortable with Git; as I mentioned, I'm still pretty new. I've barely scratched the surface of its capabilities. I seen many times how people describe how to's about LBP-2900, and 10-12 steps from start to end of how to download, unpack, build driver, fix driver, make it work... Could be there some .deb package with ready-to-go driver for Ubuntu? This printer is very popular... In general, what is meant by saying that the fraction $x$ of the variance in an analysis like PCA is explained by the first principal component? Can someone explain this intuitively but also give a precise mathematical definition of what "variance explained" means in terms of principal component analysis (PCA)?  For simple linear regression, the r-squared of best fit line is always described as the proportion of the variance explained, but I am not sure what to make of that either. Is proportion of variance here just the extend of deviation of points from the best fit line? What is a "locked" post? A post can be locked.   What does it mean to lock a post? Who can lock a post? When should a post be locked?