I'm writing a code to check for balanced brackets but I'm having a problem, probably with Java syntax. In the following code:  String s0 = "{{[[(()[])]{()}]}}}"; String[] s1 = s0.split(""); if (s1[0] == "{")     System.out.println("Ok"); else     System.out.println("Nope");   Why the comparison   s1[0] == "{"   is not true?
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?
So I was thinking about something for the past while  Consider a large spherical foam-ball with homogeneous density. Where a foam ball is defined as an object that can absorb matter with 0 friction (example: a gravitational well without an object inside). This is a purely theoretical construct.  If the foam-ball has a radius R and a charge Q. What charge must the foam-ball have, such that there is well defined sphere or horizon such that any object with a negative charge (even if it is the slightest bit) must travel faster than C in order to escape the field of the ball.  Aka what charge would turn this into a black-hole for all objects with opposite sign on their charge?  Once again I assume the foam-ball is a single particle, that doesn't repel itself... its just a very large homogenous 'thing' with charge. Using shell's read command with live editing functionality (readline like) Is there a standard (POSIX) way of asking the user some data from within a shell script, with  for example, while allowing live edition of the text being typed (what readline does)?   I know bash has read -e varname that allows for the person launching the script to use keyboard arrows for exemple, to edit or correct what has just been typed without deleting the last entered characters with backspace.   However, read -e is . And still, it is pretty cumbersome to delete all that has been wrote if you realise you made a mistake at the beginning of your long sentence... I've been trying to work out what generic means but I'm not making much progress.   You can find an example of the usage of the word generic for example : "School on Generic Singularities in Geometry" or :  "Rigidity of generic singularities of mean curvature flow"  Here is what I have so far:  I found  which mentions   "... "generic" singularities, i.e., singularities that appear for almost all maps ..."  Just after that he mentions "generic maps" but does not elaborate on what it means. He mentions it later (kind of) by saying  "...The precise definition of a generic map is very delicate; for the moment, we say only that any map may be approached by a generic map (up to an approximation on the derivatives of order r), and that any map that is sufficiently close to a generic map, in the preceding sense, is itself generic. ..."  and later  on he gives a definition of "generic singularity of a singular set":  "... A critical point $x$ of $S_r$ will be called transversally critical, or, furthermore, generic, if the tangent planes to $ \overline{f}(\mathbb R^n) $ and $F_r$ are in general position at the point $\overline{f} (x)$ of the Grassmannian, which is assumed to be ordinary on $F_r$ . ..."  Does this mean that generic and transversally critical are synonyms?  I feel I still don't understand what generic means even after reading this definition and part of the article.      Please could someone help me understand what generic means? Name of component on output side cable of a DC power adapter? What is the name of this component (circled in red) of a charger?    What are the uses of this component? What are the differences between "su", "sudo -s", "sudo -i", "sudo su"? What is different about the Mac ISO image? Proof of the duality of the dominance order on partitions Could anyone provide me with a nice proof that the  $\leq$ on partitions of an integer $n$ satisfies the following: if $\lambda, \tau$ are 2 partitions of $n$, then $\lambda \leq \tau \Longleftrightarrow \tau &#39; \leq \lambda &#39;$, where $\lambda&#39;$ is the conjugate partition of $\lambda$ (i.e. the transpose of the set of 'dots' which $\lambda$ represents).   I feel like there must be a nice clever and concise/intuitive proof of this, but all I can come up with is an ugly brute force approach based on the definition of sums of the components $\lambda_i$. Could anyone suggest a particularly nice way to obtain this result? Many thanks. How do I remove hidden backup files? I have files ending in ~ in my home directory, and I want to delete them. How do I do that? How do I prevent this backup functionality? Revision history suggests that I edited the post body, whereas I didn't I was doing some re-tagging and I noticed that the automatically generated revision comment says that I edited the post body where I only edited the tags. If two coins are flipped and one gets head, what is the probability that both get head? "Calling dibs" - what does it imply? The term "to have dibs on something" or "to call dibs on something" plays a recurring role in American film and television (e.g. ), so it gets exported a lot.   describes "dibs" as     [...] a common, "informal" convention to reserve or declare full or partial ownership of a community resource, such as a chair [...]   From the usages in the media I have seen, this convention also seems to contain some moral concept which is not described in dictionaries. For me, it looks like by calling dibs (or ), the caller actually receives the (implicit, moral) right to that resource, and this typically goes undisputed by their rivals.  Can you confirm the existence of this concept? Is this something that varies between groups of people (or maybe between regions), or is there a concensus on how to respond to this? On the iPod Touch/iPhone, since it is tied to your iTunes account, I am quite sure you can have your bought apps on multiple devices you own (can't test though, iPod Touch was stolen).  However, now I have the Motorola Droid, and am waiting for a tablet, and am considering getting a Nook and rooting it to run my own apps.  Question is, if you buy an app on the marketplace, how is the security done:   Is it tied to your Gmail account so you can share it between devices you own? Is it tied to the device? (Don't break/replace your phone!) As long as it's installed, you're OK? (If you uninstall, or wipe your device, it's gone).   I assume 3 is highly unlikely, though a possibility, so leaving it here as a potential answer to my question. What does ':' (colon) do in JavaScript? I'm learning JavaScript and while browsing through the jQuery library I see : (colon) being used a lot. What is this used for in JavaScript?   // Return an array of filtered elements (r) // and the modified expression string (t)    return { r: r, t: t }; How do I setup keyboard macros? In my daily life I'm always typing &lt;kbd&gt;Keyboard Character&lt;/kbd&gt; and I'd like to set up a macro in Ubuntu to automatically enter &lt;kbd&gt; &lt;/kbd&gt;.  I'd like to assign it to say Shift+Control+K or whatever keyboard control character combination isn't assigned and already used by Ubuntu.  Back in the day of TSR (Terminate and Stay Resident) MS-DOS programs this was possible. Certainly it must be in Ubuntu too?  Do I have to write a daemon to accomplish this?    I found other questions with no answers: ,   I found a similar question with an answer: . However that question stipulated the answer could not be AutoKey. In Microsoft Word, the following sentence is flagged.  It tells me to use "was" instead of "were"     There were half a dozen books strewn about the floor.   I would think that you would use "were" since it's a quantity more than one.  You wouldn't say, "There was twelve books strewn about the floor."  Does the use of the "half" modify it somehow? A natural number multiplied by some integer results in a number with only ones and zeros I recently solved a , which says that,     A positive integer can be multiplied with another integer resulting in   a positive integer that is composed only of one and zero as digits.   How can I prove that this is true(currently I assume that it is). Also, is it possible to establish an upper bound on the length(number of digits) of the number generated? Complex number question on proving an inequality. If $|z_1|=1,|z_2|=1$, how can one prove $|1+z_1|+|1+z_2|+|1+z_1z_2|\ge2$ Help me understand adjusted odds ratio in logistic regression I've been having a hard time trying to understand the use of logistic regression in a paper. The paper available  uses logistic regression to predict probability of complications during cataract surgery.   What is confusing me is that the paper presents a model that assigns odds ratio of 1 to baseline described as follows:     A patient whose risk profile was in the reference group for all risk indicators (ie adjusted OR=1.00 for all in Table 1) may be regarded as having a ‘baseline risk profile’, and the logistic regression model indicates a ‘baseline predicted probability’ for PCR or VL or both=0.736%.   So the probability of 0.00736 is presented with odds ratio of 1. Based on the transformation from probabilities to odds ratios: $o=\frac{p}{1-p}$, this can't be equal to 1:  $0.00741=\frac{0.00736}{1-0.00736}$.  It gets even more confusing. The composite odds ratios that represents multiple covariates having values different than the baseline is used to calculate predicted risk.      ...the composite OR from Table 1 would be 1.28 X 1.58 X 2.99 X 2.46 X   1.45 X 1.60 = 34.5, and from the graph in Figure 1, we see that this OR corresponds with a predicted probability of PCR or VL or both of around 20%   The only way to arrive at the values the paper is giving as examples is to multiply the baseline probability with composite odds like this: $0.2025=\frac{(34.50\ \times\ 0.00736)}{1\ +\ (34.50\ \times\ 0.00736)}$.  So what is going on here? What is the logic for assigning odds ratio 1 to a baseline probability that is not 0.5? The update formula I've came up with above comes up with the right probabilities for examples in the paper but this is not the direct multiplication of odds ratio I'd expect. What is it then? how to add a custom lock for the recovery and/or bootloader? Unlocking the bootloader and/or the recovery is very popular discussion across many devices. But doing so exposes a very obvious and inevitable issue with security!  An unlocked recovery means that no matter how secure you make your android lock screen, someone can easily reset phone to restore the phone to a fully functional (and lockless/insecure) state and the worst part, they don't have to erase your data(meaning they can access all your personal files and folders)!  It is almost hilarious! In fact if the phone supports insertion of external SD cards, you can even flash your own software into the phone and maybe bypass the lock screen without wiping any data.  For example: One possible loophole is using the 'Tasker' app which has a feature that can temporarily disable the keyguard. And the best part is that Tasker can be flashed using the recovery!  So is there any method by which I could add a security measure that prevents complete access to my recovery and/or boot loader that will make my phone less insecure?!  Expected answer: Method by which a custom pin/password must be entered before entering the bootloader/recovery. So that my bootloader/recovery is still technically unlocked but simply requires authentication to use (this also ensures that conventional unlocking methods won't work as the phone is not really locked!). This also means that one does not have to lose root access to ensure security! Change files with Editor that need sudo permissions I want to change files with KomodoEdit that need sudo permissions. I can't start KomodoEdit with sudo, though (for whatever reason). Can I somehow grant Komodo permission to edit those files (in particular I am talking about apache2 files and /etc/hosts)?