Error NoSuchMethodError: com.example.new.MainActivity.getActionBar
NoSuchMethodError error for getActionBar() (API-8)
How to get past a forgotten iPhone passcode? What is the population of the Star Wars Galaxy? Do I need to have antivirus software installed? Kernel of composition of linear transformations Let $f : U \to V$ and $g : V \to W$ be linear transformations on the vector spaces $U$, $V$, and $W$. Supposedly,  $$ \dim(\ker(g \circ f)) = \dim(\ker(f)) + \dim(\ker(g) \cap \operatorname{im}(f)). $$  How might I go about proving that?    (Attempt:) The $\dim(\ker(g)\cap\operatorname{im}(f))$ term suggests to me that I should define a vector space $V' = \ker(g) + \operatorname{im}(f)$ to invoke the theorem that  $$ \dim(V') = \dim(\ker(g)) + \dim(\operatorname{im}(f)) - \dim(\ker(g) \cap \operatorname{im}(f)), $$  but I don't really see where to go from there. Why is apt-get always using proxy, although no proxy is configured? I'm passing through Canada, on my way to somewhere else. I'm staying only a short time.   Is there a website, or some other way of find out out if I need a visa? Novel about alien conquerers who conduct games to select servants I read this maybe 10-15 years ago.   Aliens have conquered earth. Possibly quite some time before the time then novel is set in. They have built their own cities. They conduct periodic athletic competitions for humans similar to the current olympics. The winners are take into the city to act as servants to the masters. The protagonist is part of a human resistance movement who is competing in the games. The plan is to infiltrate the city, gather intel and escape. He wins, get in, finally has to kill his master and escape down a waste disposal system which ends up outside the city.   Anybody knows which one I am talking about? I just installed a fresh install of 32-bit 12.04 LTS Pangolin today. When I tried to install a few applications, it was really slow. But when I download a .deb or .tar.gz file from on my web browser, it is a lot faster.  Computer specs:  HP Pavilion Slimline s7700n PC  [Memory]         873.7 MiB  [Processor]      AMD Athlon(tm) 64 X2 Dual Core Provessor 3800+ x 2  [Graphics]       GeForce 6105 LE/integrated/SSE2/3DNOW!  [Disk Size] 638.5 GB  I normally get 200-400 kbps.  This is the comparison. Tags in spoilers are always visible Automating the appearance of email addresses as images Publishing pdf manuscripts on the web with emails embedded in the file results in spam.  More generally, I am looking for a way to automate the conversion of a string to an image.  It's quite easy to solve this old problem using  (more ). The trouble is that you need a distinct file and typesetting run, and you end up with unnecessary image files that you cannot delete carelessly lest you also delete non-generated images.  Can you think of a way to do this on the fly? It's understood that people will have to type the email addresses if they need to message you, but that's the point.  More briefly/concretely...  With what can one replace #1  \documentclass{article} \newcommand\showasimage[1]{#1} \begin{document} \showasimage{joe@foo.bar} \end{document}   such that #1 appears as an image?  Edit  It would be really nice if the pdf file remains vectorial. What are best practices for blocking UI when application is busy I'm writing a web app using Twitter Bootstrap with PHP on server side. My app makes regular ajax requests via jQuery and i want to disable certain parts of the UI until the server completes processing and hands back the control to Client-Side.  I wonder what would be best practices for the same? Show $4x^2+6x+3$ is a unit in $\mathbb{Z}_8[x]$ (inverting unit + nilpotent) Show that $4x^2+6x+3$ is a unit in $\mathbb{Z}_8[x]$.  Once you have found the inverse like , the verification is trivial. But how do you come up with such an inverse. Do I just try with general polynomials of all degrees and see what restrictions RHS = $1$ imposes on the coefficients until I get lucky? Also is there a general method to show an element in a ring is a unit? Alright, when I run certain commands the wrong way, (misspelled, etc.) The terminal outputs this: &gt; instead of computername:workingfolder username$, and when I type enter it goes like this:  &gt;  &gt;  &gt;   That would be if I pressed enter 3 times. How to center window title text? Does anyone know the name of travel posters from the 1930s? Is there a name for this design style - use of flat colours for dimension and shading - that was so prevalent in UK travel posters of the 1930s? Automatically rename files when they are placed in a specific directory Is it possible to automatically rename a file when it's placed in a specific directory?  For example I have a directory named "dir0".I move or copy a file named "file1" to "dir0".then "file1" should rename to "file1_{current timestamp}" Could a ship equipped with Alcubierre drive theoretically escape from a black hole? Could a ship equipped with Alcubierre drive theoretically escape from a black hole?  Also, could it reach parts of the universe that are receding faster than the speed of light from us? I've been looking around and I can't seem to find an automatic (i.e. buzz- or Twitter-like) way to follow users inside Stack Exchange. Why haven't the developers added such a feature? It could help beginner users follow other beginners with the same interests. We would be able to learn from each others' questions and pitfalls. Also, it would reduce double posting. How do I pick a part that goes into a breadboard when I order it? I have just bought some 555 timers and they are timers for microelectronic circuits...could anyone tell me what I need to search for in order to get larger ones which will fit a breadboard? Thanks Book recommendations