I am doing the exercises in the Cracking The Coding Interview book and I am trying to determine if there is a duplicate character in a string. I am using the ArrayList data structure. My method is of return type Boolean, which returns true if there is a duplicate and returns false if there is no duplicate character. I added a third return statement so the program would compile but it always returns false.  import java.util.*;  public class QuestionOneCrackingCode {      public static void main(String[] args) {         String s = "abcdefga";         ArrayList&lt;String&gt; c = new ArrayList&lt;String&gt;();         c.add(s);          System.out.print(check(c));     }      public static boolean check(ArrayList&lt;String&gt; g) {         for (int i = 0; i &lt; g.size(); i++) {             for (int j = i + 1; j &lt; g.size(); j++) {                 if (g.get(i) == g.get(j)) {                     return true;                 } else {                     return false;                 }             }         }         return 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?
Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$ A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called even if $f(-x) = f(x)$ $ \forall x \in \mathbb{R}  $   A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called odd if $f(-x) = -f(x)$ $ \forall x \in \mathbb{R}  $   Let $U_{e}$ denote the set of real-valued even functions on $\mathbb{R}$ and let $U_{o}$ denote the set of real valued odd functions on $\mathbb{R}$.   Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$   This question from Q24 of "Linear Algebra Done Right" 3rd Edition - Chp 1.4 (Subspaces). The author of the book does minimal work with functions during the chapter. I have no idea how to approach the question. There is a way to use my Galaxy tab s like a wacom table, on linux? When initiating a battle it starts off in AR mode, but then warns me saying my phone's orientation is not detected. I am then forced to turn off AR mode. Has anybody experienced this? If so, what are the solutions?    Per comments, I am unsure this is a permissions issue. I have everything turned on. Squaring pixels of GeoTIFF using GDAL I have a GeoTiff that has been supplied to me with non square pixels (I suspect due to reprojection to lat lon at some point). However the next step in my processing chain requires a Arc ASCII grid as input and so I need square pixels.   To save me trying to guess the original projection can any one tell me how to use GDAL to resample my image so the pixels become square? What makes a good entry level road bike? I've been riding a mountain bike for years, but I prefer to go longer distances on paved ground, so I think a road bike would be better. When I ask what is a good bike, I don't need brands or models - more like what components of the bike should I look for, and what should I avoid? Additionally, is it necessary to "go big or don't go at all" as far as spending - getting a real good quality road bike for $500 to a few thousand, or should I cheap out on a $100-200 road bike, as it is my first, then get a better one when I'm more experienced? IP address of host of Wi-Fi ad-hoc network? I often create a wireless ad-hoc network on my laptop running Windows 7. Now I'd like to connect to it using standard HTTP from my . I've tried 192.168.1.1 and that doesn't work. What should the address be so I can connect? Can fresh pasta sheets be used to assemble a lasagne, then left in the fridge overnight before baking? Or will this make them mushy or otherwise degrade them?  I have recently gotten into making fresh pasta, and I want to prep a lasagne the night before. I have done this before with store-bough dried noodles, but I'm not sure if doing this will have a negative effect on fresh, more delicate pasta. (p.236)  has a proof that the equation $e^z-z=0$ has infinitely many complex solutions:    I'm curious if there are any particularly elegant ways to see this, other than that given in the text. How to boot Ubuntu persistent live USB on Android? I'm discovering the possibilities offered by persistent live USB using Ubuntu 19.10 and I was wondering if it would be possible to boot with Ubuntu on Android (i.e. using your computer capabilities through your smartphone) using those multi-plug USB sticks which have both USB3 and micro-USB2.  In other way: can I get some kind of a boot menu on an Android device in order to boot with a persistent live USB in order to access my Linux computer tools and setup from a wider range of devices? So, Can linking verbs be used with "continuous tenses"? How can I String.Format a TimeSpan object with a custom format in .NET? What is the recommended way of formatting TimeSpan objects into  a string with a custom format? Take the following C# class:  c1 {  event EventHandler someEvent; }   If there are a lot of subscriptions to c1's someEvent event and I want to clear them all, what is the best way to achieve this? Also consider that subscriptions to this event could be/are lambdas/anonymous delegates.  Currently my solution is to add a ResetSubscriptions() method to c1 that sets someEvent to null. I don't know if this has any unseen consequences. What is the best way to clean lenses and filters? After removing dust with an air pomp and a brush, what are you using to remove stains from the lens and filters?  So far I'm using the liquid from a Giotto's CL 1002 cleaning kit for the lens, but I'm not sure what should I use for the filters, and if there is some better alternative.  Also, what kind of brushes are recommended? What is the typical orbital life of an artificial satellite? The orbit of satellites around Earth eventually decays, or so I read. This is typically caused either by atmospheric drag, or by tides. I would assume most satellites have a limited service life in orbit. Hence the question - What is the typical orbital life of a satellite? How long before it's successor must be launched into orbit ?  EDIT: For instance, a weather satellite How are "related" questions selected? Creating all possible line segments between all points using QGIS I want to connect all points in a point feature with every possible line segment using QGIS. For example, how a pentagon has five points with ten line segments connecting them all to form a pentagram inside. Alternatively phrased: How do I make spokes when all the points are hubs? I don't care about the order, I just want every connection between two points as one line each. Is there a tool or script that can do this in QGIS? This topic () is the closest to what I want but the plugins are no longer supported. Let $A$ be a ring that is not a field and $M$, $N$ modules over $A$. What conditions on $M,N$ (and maybe also on $A$) guarantee that $\operatorname{Hom}_A(M,N)$ is finitely generated? Is it enough to assume $M,N$ finitely generated? A white number inside a black circle. How to make a white number inside a black circle (the picture below)? I want to change numbers inside the black circle, of course.  I use Share LaTeX. I have read some articles here but anyone are not what I would like to get. I would like to get this  (the picture below) - the sixth answer.   Thanks for help. Which stats / gear can get the best our of wasteland exploration? Trying to get the best out of wasteland exploration here! I get it that you'd obviously need a big gun for survival out there, but apart from that, I'm wondering which stats / gear can get the best out of exploration.    How would you choose who to send out exploring from your dwellers. Which stat is the most important to choose explorers? Strength or endurance maybe? Does it make much of a difference equipping combat outfits? If so, whats the most important stat to boost through outfits? Using induction to prove that $\sum_{r=1}^n r\cdot r! =(n+1)! -1$ Use induction to prove that    $\displaystyle\sum_{r=1}^n r\cdot r! =(n+1)! -1$   I first showed that the formula holds true for $n=1$.  Then I put n as $k$ and got an expression for the sum in terms of $k$.  I then found the sum till the $(k+1)$th term by adding the $(k+1)$th term to both sides of the equation and compared it to the sum expression I get by plugging $k+1$ into the sum expression given in the question - they don't match.