So I need to compare my string with string that user inputs in EditText. I input same string but Java thinks that this is two different strings. I checked on spaces and didn't find them.  private void checkEditTexts(){     ...     String userAnswer = editTextAnswer.getText().toString().toLowerCase();     String rightAnswer = getResources().getString(R.string.question3_answer1).toLowerCase();      Log.v("checkET.userAnswer", "userAnswer = [" + userAnswer + "] rightAnswer = [" + rightAnswer + "]"  );      if(userAnswer == rightAnswer) {         points++;         Log.v("checkEditTexts()", "POINTS++: " + points);     }else{         points--;         Log.v("checkEditTexts()", "POINTS--: " + points);      }     ... }   Logcat:  08-29 16:47:27.494 16583-16583/....V/checkET.userAnswer: userAnswer = [song 2] rightAnswer = [song 2]  08-29 16:47:27.494 16583-16583/... V/checkEditTexts(): POINTS--: 2  08-29 16:47:27.494 16583-16583/....V/checkEditTexts(): POINTS--: 1  08-29 16:47:27.494 16583-16583/....V/checkEditTexts(): POINTS: 1   You can see that userAnswer and rightAnswer are equal and it should perform points++, but instead it does points--  Sorry for bad English.
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?
I'm using Ubuntu 12.04 &amp; everything about it is great except that it just won't resume after suspend. I've tried the suggestions listed in this thread  but none worked. I'm using Lenovo Y510P. I'm new to Ubuntu, or unix for that matter, so please let me know if there's anymore  information that I should be posting. Thanks.  update  I tried the suggestion by Dima on this post . The machine wakes up from hibernation but immediately the screen gives a screen like this     Wondering if this is an issue with the graphics card or something. How to block specific notifications from an app? A certain app I use gives me crucial notifications that I need, but also notifies me almost daily that over 80% of my RAM is used. I would like to allow this app to send me all notifications except those that contain the string "80% of your RAM" in the text of the notification.  Obviously, there is no way to filter a certain app's notifications in stock Android (other than blocking all of a certain app's notifications, but that's not what I want!), but is there a way that I can block notifications if they contain a certain string of text?  Nexus 6P running Android Marshmallow 6.0.1, if you're curious the app in question is . Good Number Theory books to start with? No space following macro without argument With a macro such as:  \def\naive{na\"{\i}ve}   I find that the space which I would hope to follow it, is absent. So, with  the \naive approach   I get     the naïveapproach   in the output. How do I bring back the space? What are good learning resources for a LaTeX beginner? Prove that $f(X)$ and $g(Y)$ are independent if $X$ and $Y$ are independent Let $X$ and $Y$ be independent random variables. Prove that $f(X)$ and $g(Y)$ are independent for any choice of measurable functions $f$ and $g$.   This sounds very obvious, but I have no idea how to approach it.  EDIT: Two random variables are independent if $\Pr\{X = x \text{ and } Y = y\} = \Pr\{X = x\} \cdot \Pr\{Y = y\}$ To show that $2$ | $x^{2n} - x^n$, $n \in \mathbb{Z^+}$ is the following adequate? Create model from XYZ data points How can I pin a program to the Windows 7 Taskbar, with parameters? How can a function with a hole (removable discontinuity) equal a function with no hole? I've done some research, and I'm hoping someone can check me. My question was this:  Assume I have the function $f(x) = \frac{(x-3)(x+2)}{(x-3)}$, so it has removable discontinuity at $x = 3$. We remove that discontinuity with algebra: $f(x) = \frac{(x-3)(x+2)}{(x-3)} = (x+2)$. BUT, the graph of the first function has a hole at $x = 3$, and the graph of the second function is continuous everywhere. How can they be "equal" if one has a hole and the other does not?  I think that this is the answer:   Because the original function is undefined at the point $x = 3$, we have to restrict the domain to $\mathbb{R} \setminus 3$. And when we manipulate that function with algebra, the final result, $f(x) = (x + 2)$ is still using this restricted domain. So even though the function $f(x) = (x+2)$ would not have a hole if the domain were all of $\mathbb{R}$, we are sort of "imposing" a hole at $x = 3$ by continuing to throw that point out of the domain.   And then just to close the loop: Removing the removable discontinuity is useful because it allows us to "pretend" that we're working with a function that is everywhere continuous, which helps us easily find the limit. But the reality is that the function $f(x) = (x +2)$ is actually NOT continuous everywhere when we restrict the domain by throwing out the point 3. Or am I now taking things too far?   Thanks in advance!  EDIT: For anyone coming across this in the future, in addition to the excellent answers below, I also found this other question about the  helpful. Inertial forces and centre of mass Is inertial force always attached to the centre of mass of the object? Why? What rules cause this to happen?  See the  below of the leaned bike in a corner.    The force $m\frac{v^2}{r}$ pointing to the right is the centrifugal force (inertial force - because it's a rotating reference frame, therefore a non-inertial reference frame). It is attached to the centre of gravity of the bike.  I'm thinking that inertial force is attached to the centre of mass because of the fact that it should simply avoid creating a torque on the object. That's intuitive, but there must be a general rule that allows us to conclude that. Is there a formula for $\sin(xy)$ Can we express a trigonometric function for the product of two angles as a function of trigonometric functions of its factors?  For example: Is there a formula for $\sin(xy)$ as a function of $\sin x$ and $\sin y$ or other trigonometric functions of $x$ and $y$. For each $y \in \mathbb{R}$ either no $x$ with $f(x) = y$ or two such values of $x$. Show that $f$ is discontinuous. This is from Apostol's Mathematical Analysis.  Let $f$ be a function defined in $[0, 1]$ such that for each real number $y$ either there is no value of $x \in [0, 1]$ such that $f(x) = y$ or there are exactly two such values of $x$. Prove that a) $f$ must be discontinuous on $[0, 1]$. b) $f$ has an infinite number of discontinuities in $[0, 1]$.  Long back I had tried to solve the problem. I reasoned for a) as follows: Suppose that $f$ is continuous and let $m, M$ be its minimum and maximum values on $[0, 1]$. Clearly if $m = M$ then $f$ is constant and clearly for every $x \in [0, 1]$ we have $f(x) = m = M$ which contradicts given property of $f$. So we must have $m &lt; M$. Clearly there are now four distinct points $a, b, c, d$ in $[0, 1]$ such that $f(a) = f(b) = m, f(c) = f(d) = M$. By checking possible linear orderings of $a, b, c, d$ I could find a find a value of $y \in (m, M)$ for which there exist more than 2 values of $x$ such that $f(x) = y$. However this approach looks very clumsy and I suspect much simpler and easier proof is possible. Part b) seemed bit complex and my only guess was that probably $f$ was discontinuous on each subinterval of $[0, 1]$ but I could not prove this claim (may be the claim is wrong!). Perhaps there is a simpler solution to this part of the problem. Apostol's also asks to provide an example of such a function. Any hints on the overall problem will be appreciated.  Update: After looking at Marc's answer, I think I have found a way to show that there are infinitely many discontinuities. Earlier the solution was a part of the question itself but it made the question look quite lengthy hence I moved it to a separate answer. In MySql's interpreter, it's very easy to dump a table to the screen along with its field names.   There seems to be no simple way to export a table to a tab-delimted or CSV outfile including its column headers.  I'm trying to do this using only SQL or the Linux command line, without writing a program in another language.  Thank you Correlation coefficient between a (non-dichotomous) nominal variable and a numeric (interval) or an ordinal variable I've already read all the pages in this site trying to find the answer to my problem but no one seems to be the right one form me...  First I explain you the kind of data I'm working with...  Let's say that I have an array vector with several names of city, one for each of 300 users. I also have another array vector with scores response to a survey of each user or a continuous value for each user.  I would like to know if exist a correlation coefficient that compute the correlation between these two variables so, between a nominal and a numeric/continuous or ordinal variables.  I've searched on the Internet and in some pages they suggest to use the contingency coefficient or Cramer's V or Lambda coefficient or Eta . For each of this measure the just say that they could be applied for such data in which we have a nominal variable and interval or numerical variable. The thing is that searching and searching, trying to understand every one of them, sometime is written or watching the examples that they are reasonable to use them if you have dichotomous nominal variable, except for Cramer's V, other time is not written any requirement for the type of data. A lot of other pages say that is right to apply regression instead, that is right, but I would just simply like to know if there is a coefficient like pearson/spearman for this kind of data.  I also think that is no so properly to use Spearman Correlation coeff since the cities are not sortable.  I have also built the function of Cramer'sV and Eta by myself (I'm working with Matlab) but for Eta they don't talk about any p-value to see if the coefficient is statistically significant...  In the matlabWorks site there is also a nice toolbox that says to compute eta^2 but the kind of input it needs is not understandable.  Is here someone that have done a test like mine? If you need more detail to understand the kind of data I'm using just ask me and I'll try to explain you better. I have a Canon XTI which I've been using for a few years now. Most of the time I'm been shooting in one of the "semi-manual" modes like aperture priority or shutter priority, but now I'd like to try using full manual mode. I should have a new EF-S 17-55 f/2.8 delivered when I get home today. Before I was using a variable aperture Sigma 17-70 which made manual mode more difficult with the aperture changing arbitrarily.  I understand the effect of changing aperture and shutter speed, but right now I'm accustomed  to only controlling one at a time. The camera is usually setting the other to get the right exposure automatically for me. So if I'm controlling both how do I know I have the correct exposure? I understand I need to use the metering in my camera but I'm not sure exactly how do do that.   First when should I be using each of the metering modes (Evaluative, Partial, Center weighted, or Spot)? These just change the area of the scene which is metered correct?  How do I know what the meter should read off a specific object? Obviously if I just happen to be shooting a 18% gray wall then it should be at zero, but that can't apply to everything? If I'm shooting a black cat and take a spot meter reading off of the cat then the meter should read less then zero right? But how do I know how much less then zero? Are there rules of thumb I can follow? I've ordered a couple gray cards with my new lens. So experimenting with those should help.  How often should I be changing these settings? Say I'm at a party indoors which is consistently lit. I should be able to set the aperture, shutter speed, and ISO and just forget about it unless the lighting changes correct? Does the same apply to outdoor scenes? I've been hesitant to use manual mode in the past because I felt like I was spending a lot of times messing with settings before each shot. But not I'm realizing that this is really only the case when the lighting changes, or I want a different style of photo such as a different depth of field.  Finally, does exposure change with distance to the subject? For example say I want to take a picture of a statue with correct exposure using a gray card. I'd place the card on the statue, and while being careful not the block the light on the card find the correct exposure by spot metering the card. If I were then to step back 20' to get the whole statue in frame would I still have the correct exposure? OpenGL GLX context is not using direct rendering, which may cause performance problems. (steam) AMD DRIVER When I start steam in a terminal, I get the following error messages   charlie@SteamMPL:~$ steam rm: no se puede borrar «/home/charlie/.steam/steam»: Es un directorio rm: no se puede borrar «/home/charlie/.steam/bin»: Es un directorio Running Steam on ubuntu 14.04 64-bit STEAM_RUNTIME is enabled automatically [2014-08-03 11:50:13] Startup - updater built Jul 15 2014 18:14:26 Installing breakpad exception handler for appid(steam)/version(1405474565_client) libGL error: failed to load driver: swrast Looks like steam didn't shutdown cleanly, scheduling immediate update check Installing breakpad exception handler for appid(steam)/version(1405474565_client) [2014-08-03 11:50:14] Checking for update on startup [2014-08-03 11:50:14] Buscando actualizaciones disponibles... Installing breakpad exception handler for appid(steam)/version(1405474565_client) [2014-08-03 11:50:14] Download skipped: /client/steam_client_ubuntu12 version 1405474565, installed version 1405474565 [2014-08-03 11:50:14] Nothing to do [2014-08-03 11:50:14] Verificando instalación... [2014-08-03 11:50:14] Performing checksum verification of executable files [2014-08-03 11:50:15] Verification complete Gtk-Message: Failed to load module "overlay-scrollbar" Gtk-Message: Failed to load module "unity-gtk-module" Installing breakpad exception handler for appid(steam)/version(1405474565_client) Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number [0803/115015:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation libGL error: failed to load driver: swrast Error: OpenGL GLX context is not using direct rendering, which may cause performance problems.   Hardware information:   CPU: AMD Athlon x4 760k  GPU: AMD Radeon R7 250 1 GB GDDR5 (Driver: Catalyst 14.4) RAM: 8 GB DDR3 1600   What can I do to circumvent this issue? Consider a block cipher with a key of size 128 bits but a small block size, say 32 bits.  Is this kind of block cipher secure?  I would like to know to what extent I can use a small block cipher, like a 32 bit block cipher. What are the constraints so that the use is acceptable in a real life application.  For instance, if we use a one-time key, that is, to encrypt only one message. Besides, the message could be small.  Suppose that when we want so send one file, we perform a key agreement so that we use the key for one message. This scenario is not efficient, but the CPA find-then-guess game is not adequate in this case. Increasing Letterspace for words in caps or small caps Some typographers say it's a good habit to increase the letterspace when writing words in caps or small caps. So my question is, how to do it with pdflatex and/or xelatex? And while we're at it, which words would you alter this way? Acronyms like USA, NATO, IBM, GNU, etc.? How about words like PCs, UdSSR, FreeBSD or TV-Station? I am having a problem understanding displacement maps. I'm starting to think that I don't understand them at all.  Clarifying My Understanding  My understanding (which might be completely wrong), is that a displacement map is a gray-scale image whereby a value of 0.5 produces no displacement, >0.5 produces displacement in the positive direction, and &lt;0.5 produces displacement in the negative direction. This, however, does not seem to match my actual observations in Blender.  I am using a displacement map within Cycles, plugging it into the Displacement socket on the Material Output node (I am also using the new experimental adaptive subdivision and micro-vertex displacement). I note that a value of 0.5 actually produces a displacement in the positive direction, causing the whole mesh to jump up slightly, as well as creating the peaks and valleys that you would expect for >0.5 and &lt;0.5 values respectively.  This affects my entire understanding of displacement maps. Why is this happening? Why is a value of exactly 0.5 creating displacement? Further, how are you supposed to arrange and line up objects in your scene when, in rendered view, the displacement maps will push them out of position, even if those maps are only supposed to create displacement in specific areas.  The Problem in Practice  This is the problem I am having at the moment. I have a plane which is supposed to be a snowy field, and I am using a displacement map to give some depth to the snow. In rendered view, my plane jumps up significantly. This is what lead me to investigate my understanding of displacement maps, and to this question.  Additionally, what is the correct way to increase and decrease the strength of a displacement map? At the moment, I will run them through a Math node set to multiply, however, as you might imagine, this exaggerates the issue that I am complaining about above.  To be clear, however, I am not using a math node when experiencing the "jump up" for 0.5 values. This is not the source of my problem, but another aspect to it.