when i am comparing a string that is concatinated and comparing the objects of the concatinated string and normal string its showing false. I thought that the Strig literal "kalyansreekar" is already present in String constant pool. can soomeone explain me why this is happening and also the implementation code of string concatination. Thank you.  String a="kalyan"; String b=a+"sreekar"; String c="kalyansreekar"; System.out.println(b==c);   "I expect the result to be true, but the actual output is false"
I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?
Do we need a global test before post hoc tests? I often hear that post hoc tests after an ANOVA can only be used if the ANOVA itself was significant.    However, post hoc tests adjust $p$-values to keep the global type I error rate at 5%, don't they?  So why do we need the global test first?  If we don't need a global test is the terminology "post hoc" correct? Or are there multiple kinds of post hoc tests, some assuming a significant global test result and others without that assumption? A slick proof that a field which is finitely generated as a ring is finite It is a known fact that if $k$ is a field that is finitely generated as a ring, which is the same as having a surjective ring homomorphism $f:\mathbb{Z}[x_1,\dots,x_n]\to k$ for some $n\in \mathbb{N}$, then $k$ must be finite. Since finite generation as a ring implies finite generation over the prime field ($\mathbb Q$ or $\mathbb F_p$), by Noether normalization it follows that $k$ must be a finite extension of its prime field. In positive characteristic this finishes the job and in zero characteristic, should lead quickly to a contradiction, though I don't see immediately how. Is there an elementary/slick proof of this fact? Using customized Coordinate System in ArcGIS Desktop? I'm using retextured snowballs and eggs for the different paintballs for two teams in a paintball map, so I can't replace the eggs with snowballs.  I have tried using /gamerule doMobSpawning false, but that still allows the chickens to spawn. I have also tried using /tp @e[type=Chicken] 0 0 0 on a repeating command block to quietly remove the chicken, but there's still a very noticeable frame where the chicken is visible. /effect @e[type=Chicken] minecraft:invisibility 10 1 false isn't fast enough, either.  I'm not using any plugins or mods.  tl;dr Without snowballs, how can I stop chickens from appearing for even a single frame. Empty vector menu in QGIS on PC with French as default language I installed QGIS 3.0.0 on a PC with French as default language. After changing the language of QGIS to English, the 'Vector' menu is empty and there is a French 'Vecteur' menu. Any ideas how to fix this? I cannot change the system language. This is a  about securing public DNS resolvers   Open DNS servers seem pretty neat and convenient, as they provide IP addresses that we can use consistently across our company regardless of where they are located. Google and OpenDNS provide this functionality, but I'm not sure that I want these companies to have access to our DNS queries.  I want to set up something like this for use by our company, but I hear a lot about this being dangerous practice (particularly in regards to ) and I want to make sure that we do this right. What things do I need to keep in mind when building this type of environment? I have to give a combinatorial proof of  $$\sum_{k=1}^nk{n\choose k}^2=n{2n-1\choose n}.$$  I find it difficult to solve such problems. I'm not a brilliant person and never will be so I need to have algorithms to solve most problems. Usually I won't just "see" solutions unless I have a thorough enough understanding of a theory. This is also the case here. I know what the symbols mean, but I don't see what I should count and how to obtain the identity.  I think the right-hand side counts $n$-element subsets of a $(2n-1)$-element set with one element chosen to be "special". I think I should find a partition of the set of such subsets into $n$ parts so that the left-hand side is the sum of the cardinalities of the parts. Is there $n$ of anything on the right-hand side? Well, there are $n$ choices for the "special" elements, but only after I've chosen the $n$-element subset. Otherwise I can choose the "special element" in $2n-1$ ways.  This is a homework problem so I probably shouldn't ask for a full solution. But I would like to have some guidelines for approaching such problems, perhaps based on this example. If I have multiple objects selected can I use scaling to make the objects closer together (without rescaling the objects)? Change post permalink to external URL from custom field Is the ArcGIS Server JavaScript API free to use? The 2008  announcing the ArcGIS Server JS API says:     Everyone can use the ArcGIS JavaScript API. There is no fee for using the ArcGIS JavaScript API or deploying an application built with it.   But Esri's  page says "Contact us for pricing".  Which is correct? How to add texture to fill colors in ggplot2 Bird flying in a cage Assume that you are holding a cage containing a bird.  Do you have to make less effort if the bird flies from its position in the cage and manages to stay in the middle without touching the walls of the cage? Does it make a difference whether the cage is completely closed or it has rods to let air pass? A common good practice in Machine Learning is to do feature normalization or data standardization of the predictor variables, that's it, center the data substracting the mean and normalize it dividing by the variance (or standard deviation too). For self containment and to my understanding we do this to achieve two main things:   Avoid extra small model weights for the purpose of numerical stability. Ensure quick convergence of optimization algorithms like e.g. Conjugate Gradient so that the large magnitude of one predictor dimension w.r.t. the others doesn't lead to slow convergence.   We usually split the data into training, validation and testing sets. In the literature we usually see that to do feature normalization they take the mean and variance (or standard deviation) over the whole set of predictor variables. The big flaw I see here is that if you do that, you are in fact introducing future information into the training predictor variables namely the future information contained in the mean and variance.  Therefore, I do feature normalization over the training data and save the mean and variance. Then I apply feature normalization to the predictor variables of the validation and test data sets using the training mean and variances. Are there any fundamental flaws with this? can anyone recommend a better alternative? Can someone show me a straightforward proof that  $\lim_{m\to\infty}(1+\frac{r}{m})^{mt}=e^{rt}$  Thanks! How can I disable the Document Library drag and drop function? Before I start - I'm new to this SharePoint development lark and am slowly familiarising myself with it.  We're using SharePoint online and I have amended the SharePoint out-of-the-box document library to include some extra fields that are required when the user adds a new document.  If the user creates or uploads a new document then they are prompted to enter the required information. However if they use the drag and drop functionality the entry of the necessary fields is bypassed.  During my search I came across  which asks how to enforce metadata entry (which would be another good option for me). It also mentions disabling the drag and drop functionality by editing dragdrop.js and removing content from various methods.  I've had a look at the site collection I'm working on (to which I have full control) and I can't seem to find dragdrop.js (or the layouts folder for that matter).   Is this something that's held at site collection level or is it held at a higher level? I don't have admin rights above my site collection, do I need them? Do I need to use Visual Studio to make the necessary changes? (Currently I'm doing things through the web and having a bit of a play with Napa I don't have Visual Studio installed)  When I get there is it obvious what methods need to be removed? How can I tell SharePoint to use the new version of dragdrop.js? Is it just a case of saving a copy of the existing one to a different name and then editing the existing file?      I suppose the best place for me to have asked this question would probably have been on the existing post, but I am unable to post a comment on there, sorry... Injectivity of Homomorphism in Localization Let $\alpha:A\to B$ be a ring homomorphism, $Q\subset B$ a prime ideal, $P=\alpha^{-1}(Q)\subset A$ a prime ideal. Consider the natural map $\alpha_Q:A_P\to B_Q$ defined by $\alpha_Q(a/b)=\alpha(a)/\alpha(b)$. Suppose that $\alpha$ is injective. Then is $\alpha_Q$ always injective?    I think so, but I'm clearly being too dense to prove it! My argument goes as follows.  Let $\alpha(a)/\alpha(b)=0$. Then $\exists c \in B\setminus Q$ s.t. $c\alpha(a)=0$. If $B$ is a domain we are done. If not we must exhibit some $d\in A\setminus P$ s.t. $da=0$. Obviously this is true if $c =\alpha(d)$. But I don't see how I have any information to prove this!  Am I wrong and this is actually false? If so could someone show me the trivial counterexample I must be missing?   Many thanks! Windows Backup & Restore: What to Keep from AppData? A couple years ago, my father made a backup of one of our computers using Windows Backup and Restore. It was either Windows Vista or Windows 7, not sure which. He backed up the entire computer, including Program Files, AppData, My Documents, everything, and now it is on .zip files on a WD Passport with 300GB, I'm not sure exactly what it is called. Now I am trying to decide which files to keep and which to delete. Most of what we would keep are files, as we would need CD's to use the programs, and I'm pretty sure they would install everything all over again. That pretty much leaves out Program Files, however, I'm not sure about AppData. For example, my mother used Greetings Workshop and wants some files from there, and she may want to keep some default settings she used. I am talking generally here, as I'm sure some programs have different ways of saving things in AppData.  What, if anything, should I keep from AppData, and what should I delete? I read an interesting question here in the forum () and came up with the following doubt: even though its diffraction angle is too small to be detected, if we had the possibility to detect it, what would the diffraction of a soccer ball through a pair of posts look like? I mean, in the case of electrons, there is a screen in which the diffraction pattern can be appreciated. But what about this case? Would we see lots of soccer balls in different places or what? Is it possible to repeat my track object along a path? I tried using the method shown here  using an array and then a curve modifier, but this happened when I added the curve modifier and chose the path as the curve object. Java in Eclipse: Where do I put files on the filesystem that I want to load using getResource? (e.g. images for an ImageIcon) I know the file needs to be where the getClass().getResource(filename) can find it, but I don't know where that is.  I'm interested both in where to put the files on the filesystem itself, and how to go about using Eclipse's functionality to set up the resources.