i work in NetBeans and my code does no working.Reason in description/
What is a NullPointerException, and how do I fix it?
Evaluation of $\displaystyle \int_{0}^{1}\frac{x\ln (x)}{\sqrt{1-x^2}}dx$   $\bf{My\; Try::}$ Let $\displaystyle I = \int_{0}^{1}\frac{x\ln x}{\sqrt{1-x^2}}dx\;,$ Put $x=\cos \phi\;,$ Then $dx = -\sin \phi d\phi$  and Changing Limit, We get  $$\displaystyle I = -\int_{\frac{\pi}{2}}^{0}\cos \phi \cdot \ln(\cos \phi )d\phi = \int_{0}^{\frac{\pi}{2}} \ln(\cos \phi)\cdot \cos \phi d\phi$$  Now Using Integration by parts, We get  $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\frac{\sin^2 \phi}{\cos \phi}d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\frac{(1-\cos^2 \phi)}{\cos \phi}d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\int_{0}^{\frac{\pi}{2}}\sec \phi d\phi-\int_{0}^{\frac{\pi}{2}}\cos \phi d\phi$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\left[\ln\left|\sec \phi+\tan \phi\right|\right]_{0}^{\frac{\pi}{2}}-\left[\sin \phi\right]_{0}^{\frac{\pi}{2}}$$  So $$\displaystyle I = \left[\ln(\cos \phi)\cdot \sin \phi\right]_{0}^{\frac{\pi}{2}}+\left[\ln\left|\sec \phi+\tan \phi\right|\right]_{0}^{\frac{\pi}{2}}-1$$  Now How can I solve after that, Help Required, Thanks How to install Metasploit and Armitage I want to install metasploit and armitage on my ubuntu 16.04 LTS laptop running kernel 4.6  I've read blogs and posts on how to install it but the problem is is that they are outdated. The packages are not there anymore and or the commands dont work.  If anyone can give me an updated tutorial on how to install it that would be great. I also think other users that see this post and want to install it will also be thankful. Thanks. Subfiles failing with custom class How to center a listing? I'm trying to get some console output in my homework. I put it in a listings environment but I want it to be centered horizontally on the page.  The only thing I get centered is the caption ;-/  \begin{minipage}{1\textwidth} \begin{center} \begin{lstlisting}[caption={Ausgabe des C-Programms},label={ggt_c_ausgabe}] a  |  b  |  q  |  u  |  s  |  v  |  t   ---------------------------------------- 78 |  21 |   1 |     |   1 |   1 |  -1  21 |  15 |   3 |   1 |  -3 |  -1 |   4  15 |   6 |   1 |  -3 |   4 |   4 |  -5   6 |   3 |   2 |   4 | -11 |  -5 |  14   3 |     |   2 | -11 |  26 |  14 | -33  ---------------------------------------- \end{lstlisting} \end{center} \end{minipage} I will try to be as explanatory as possible with my question. Please also note that I have done my share of googling and I am looking for simple language preferable with some example so that I can get some insight in this subject.  My question is what is so special about $c$? Why only $c$. Its like chicken and egg puzzle for me. Does Einstein reached to $c$ observing light or does he got to light using some number which turned out equal to $c$.   Why is $c$ not relative. If something has zero rest mass like a photon why they only travel at $c$ in vacuum and not with $c+1$ or $c-1$? Programmatically obtaining Big-O efficiency of code I wonder whether there is any automatic way of determining (at least roughly) the Big-O time complexity of a given function?  If I graphed an O(n) function vs. an O(n lg n) function I think I would be able to visually ascertain which is which; I'm thinking there must be some heuristic solution which enables this to be done automatically.  Any ideas?  Edit: I am happy to find a semi-automated solution, just wondering whether there is some way of avoiding doing a fully manual analysis. How do I  prevent .xsession-errors from eating disk space? Is there any way to completely disable the .xsession-errors file?  I have it as a symlink to /tmp so that my laptop hard disk can (hopefully) go to sleep for once, but at least 95% of the stuff in the file (it fills up at about 500k an hour) is...  (nautilus:1618): GLib-GObject-CRITICAL **: g_value_get_object: assertion `G_VALUE_HOLDS_OBJECT (value)' failed  which is total garbage to me.  I have tried doing a symlink to /dev/null but that does not work (the resulting link is overwritten), and I also do not want the activity so that hopefully my laptop can go to sleep for once.  I am using Ubuntu 11.04, with no special add-ons to Nautilus. Flattening iterator Which characters played the parts of the lineup discussed by Rusty and Daniel? In planning the heist, Rusty names a number of roles that are going to be needed to pull off the job.      Off the top of my head, I'd say you're looking at a Boesky, a Jim Brown, a Miss Daisy, two Jethros, and a Leon Spinks. Not to mention the biggest Ella Fitzgerald ever.   Which characters in the film lined up with these named roles? Can I install Python 3.x and 2.x on the same Windows computer? Restarting Mathematica causes an animation to fail to run Update SQL Server table with local data How to discover USB storage devices and writable CD/DVD drives (C#) How can I discover any USB storage devices and/or CD/DVD writers available at a given time (using C# .Net2.0).  I would like to present users with a choice of devices onto which a file can be stored for physically removal - i.e. not the hard drive. Choosing GeoCoding service? I'm looking for a web service providing a full address based on coordinates (and reverse).  I'm ready to pay for that service.  I don't want to use Google's API. Wulfgar won't teach me Unrelenting Force's final word after Arngeir accepts the Horn of Jurgen Windcaller What does = +_ mean in JavaScript Example 4.21 in Baby Rudin: Why is the inverse of this function not continuous at this point? Here's Theorem 4.17 in the book Principles of Mathematical Analysis by Walter Rudin, 3rd edition:      Suppose $f$ is a continuous 1-1 mapping of a compact metric space $X$ onto a metric space $Y$. Then the inverse mapping $f^{-1}$ defined on $Y$ by $$ f^{-1}( f(x) ) = x \ \ \ \ \ \ \ ( x \in X ) $$ is a continuous mapping of $Y$ onto $X$.    Now in Example 4.21 Rudin illustrates that compactness of $X$ is essential in Theorem 4.17.   So here is Example 4.21:   Let $X$ be the half open interval $[0, 2 \pi )$ on the real line, and let $\mathbf{f}$ be the mapping of $X$ onto the circle $Y$ consisting of all points whose distance from the origin is $1$, given by $$ \mathbf{f}(t) = ( \cos t, \sin t ) \ \ \ \ \ \ ( 0 \leq t &lt; 2 \pi). $$ Then this function $\mathbf{f}$ is of course continuous and injective. But Rudin asserts that the inverse function is discontinuous at the point $(1, 0) = \mathbf{f}(0)$. How to demonstrate this fact rigorously?  So far in the book, Rudin has not discussed the functions $\cos$ and $\sin$. So can we come up with an example that uses only what Rudin has discussed? How to create a rounded cone What is the difference between <%# and <%= in ASP.NET MVC? In my assignment I have to prove that the following function doesn't have a limit:  $$f(x)=\frac{x}{x-\lfloor{\sin x}\rfloor}$$ when $${x \to 0}$$  In other words, I have to prove that for every $\delta$ such that $0&lt;|x-{x_0}|&lt;\delta,$ $|f(x)-L|&gt;\epsilon$.  In fact, I don't even know how to start. Do I choose my $\delta$? I know that the sin function has certain values that's supposed to help me. How do I use it?  I have to prove this by definition, so I can't use limit arithmetic for example  Thanks.