What is the difference between these two following statements?  String s = "text";  String s = new String("text");
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?
Is it possible to induce Mathematica to chop off parts of Graphics objects that exist outside of a Frame? Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics? There seem to be two different things one must consider when representing a symmetry group in quantum mechanics:   The universal cover: For instance, when representing the rotation group $\mathrm{SO}(3)$, it turns out that one must allow also $\mathrm{SU}(2)$ representations, since the negative sign a "$2\pi$ rotation" induces in $\mathrm{SU}(2)$ is an overall phase that doesn't change the physics. Equivalently, all representations of the Lie algebra are what we seek. ($\mathfrak{so}(3) = \mathfrak{su}(2)$, but although every representation of the algebra is one of the universal cover, not every representation of the algebra is one of $\mathrm{SO}(3)$.) Central extensions: In conformal field theory, one has classically the  of infinitesimal conformal transformations. From the universal cover treatment one is used to in most other cases, one would expect nothing changes in the quantum case, since we are already seeking only representation of an algebra. Nevertheless, in the quantization process, a  appears, which is often interpreted to arise as an "ordering constant" for the now no longer commuting fields, and we have to consider the  instead.   The question is: What is going on here? Is there a way to explain both the appearence of universal covers and central extensions in a unified way? I understand Big-O notation, but I don't know how to calculate it for many functions. In particular, I've been trying to figure out the computational complexity of the naive version of the Fibonacci sequence:  int Fibonacci(int n) {     if (n &lt;= 1)         return n;     else         return Fibonacci(n - 1) + Fibonacci(n - 2); }   What is the computational complexity of the Fibonacci sequence and how is it calculated? I'm facing this frustrating "feature" that I can't seem to remedy; when I duplicate an object (and now, even when I create two completely new objects), their transformations/scaling is synchronized. This is extremely annoying when trying to use any sort of transformation keyboard shortcut.  It should be noted by going to the properties menu (N) and manually setting the properties works just fine.  For instance, here is just the camera selected (trust me, I made sure):   And when I try to transform by clicking+dragging on the X axis OR by hitting G->X, this happens:   They are not grouped (verified by going to the Groups list up in the Scene panel) and they do not have parents (verified by going to Object->Relations).  I have tried the unlink command as well, to no avail.  I have seriously run out of options; what did I change to have my G->X shortcuts transform multiple objects? It seems completely at random, too; certain objects seemed to be "linked" to other random objects, and this "linking" is guaranteed when duplicating even when I do a non-linking duplicate (Shift+D).  What gives? To consume REST services there is a lot of boilerplate code needed:   Build Apex Objects to model the responses Code to deserialize REST responses to those classes Handling of HTTP requests, responses and errors ...   Did anyone come up with patterns or best practices codified into an open source library or framework that one could just reuse in a similar project without reinventing the callout-wheel over an over again?  Like the zillions of trigger-frameworks that exist as repos on Github... A simple algebra that is not semisimple Are there any guidelines for converting cooking recipes from Regular Ovens to Convection? I was looking to buy a Convection Oven and wanted to know if there are any general differences in baking methods between the two. I'm looking for an ASCII art generator (text is preferred, but images will do too) in the  style, but with text instead of trains. Any suggestion? How to include custom non-system folder under This PC in Windows 8.1? I've recently upgraded from Windows 8 to 8.1 and noticed the restructured This PC folder, formerly Computer.   What I want to achieve is to include custom folder under "This PC".    What I've found after googling is that what is displayed under "This PC" is stored in registries under   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\NameSpace  However those folders (such as Desktop, Documents, etc) are referenced via CLSID and the folder I want to include in the list does not have CLSID. I have recently installed lubuntu 11.10 on my old laptop (acer aspire 5315 celeron) and observed that fan is not working properly on lubuntu side.I find it strange that it is working perfectly under window vista.   How could I solve this problem? How to use maths symbols in text mode? I try to add a center dot with \circ but it fails to compile. How to use maths symbol in text mode? The error message is   ovak, slovenian, spanish, swedish, turkish, turkmen, ukrainian, uppersorbian,  welsh, loaded. (/usr/local/texlive/2012/texmf-dist/tex/latex/base/article.cls Document Class: article 2007/10/19 v1.4h Standard LaTeX document class (/usr/local/texlive/2012/texmf-dist/tex/latex/base/size10.clo)) (./untitled-1.aux) ! Missing $ inserted. &lt;inserted text&gt;              $ I would like to replace the usual \hat in maths with a larger one, but I do not want it to stretch. The size I want is "the smallest \widehat" (as in $\widehat{.}$). Is there a way to put that one above a wide character like M ($\widehat{M}$ would stretch and give be an even wider hat).  I guess I have a lack of understanding for the mechanism behind accents that extend, so feel free to explain. $$\overline{z}=z^n$$ where $n\in \mathbb{N}$   So I have started with moving the polar representation as the expression is in the n-th power  $$rcis(-\theta)=r^ncis(n\theta)$$   I can not multiply both sides in $r^{(-n)}$ as $n\in \mathbb{N}$ how should I continue? "We plan" versus "we are planning" Is there a semantic difference between the following two sentences?     In the future, we are planning to migrate our tool to the Z3 solver.         In the future, we plan to migrate our tool to the Z3 solver. Does this email mean that I have been granted the visa? Please help me to stop auto login in Skype. There is an account that is always login again and again, although I chose to logout and sign in with another Skype name. I tried on Settings/applications/Skype to kill the account and to quit synchronise, but still whenever I open Skype again, I'm logging in automatically. Two definitions of $\limsup$ Here are two equivalent definitions of $\limsup_{n\rightarrow\infty} a_n$:   Let $u_n=\sup\{a_n, a_{n+1}, a_{n+2},\ldots\}$. Then $$\limsup_{n\rightarrow\infty} a_n = \lim_{n\rightarrow\infty} u_n =    \lim_{n\rightarrow\infty}\left(\sup\{a_n,a_{n+1},\ldots\}\right)$$ Let $E$ be the set of all subsequential limits of $\{a_n\}$. Then $$\limsup_{n\rightarrow\infty} a_n = \sup E$$   I'm curious as to which one people usually learn first, or which one people find more intuitive. Baby Rudin only has the second definition, but doesn't mention the first as far as I know.  As far as intuition, I think of the second definition as "the biggest limit point." I'm not sure how to think of the first definition though. I can see that $u_n \ge u_{n+1}$ for all $n$, but I'm not sure how to interpret the limit of those $u_n$ conceptually.  Are there any other ways to conceptualize $\limsup$? Let $x = (a, b), y = (c, d) \in \mathbb{Z}^2$. What is the condition on $a, b, c, d$ so that ${x, y}$ is a basis?   My answer: $ad\neq bc$ and $gcd(a, c) = gcd(b, d) = 1$.  The first condition ensures that they aren't the same vector; the second ensures that we can actually "get" all of the integer values/lattice points.  Is this correct?  Thanks. How can I share an iCloud photo album? Why isn't dark matter just ordinary matter? There's more gravitational force in our galaxy (and others) than can be explained by counting stars made of ordinary matter. So why not lots of dark planetary systems (i.e., without stars) made of ordinary matter? Why must we assume some undiscovered and unexplained form of matter?