NullPointerException: Attempt to read from field 'java.lang.String com.salmanibrahim.firebasechat.model.User.name' on a null object reference
What is a NullPointerException, and how do I fix it?
I just installed Call of Duty 4 and when I try to run the single player mode nothing happens. I just see a quick flicker on the desktop but the game doesn't launch. When I try to run it again, it gives me this message:      It appears that cod4 did not quit properly the last time it ran. Do you want to run the game in safe mode?    Multiplayer seems to work fine and when I try to switch to single player from the multiplayer menu the same thing happens, it just goes back to my desktop and that message shows up again I know this issue has been addressed before with different software, but how do I do it with Shapely?  I have a polygon with a very small gap on the interior of the shape:    Here is a close up:    The polygon is valid so I can't use the buffer trick, and simplifying the polygon also doesn't work. $ a+b+c+d=6 , a^2+b^2+c^2+d^2=12$ $\implies$ $ 36 \leq 4(a^3+b^3+c^3+d^3)-(a^4+b^4+c^4+d^4) \leq48 $ Let $a , b, c, d$ be real numbers such that $$ a+b+c+d=6 \\ a^2+b^2+c^2+d^2=12$$  How do we prove that $$ 36 \space \leq\space 4(a^3+b^3+c^3+d^3)-(a^4+b^4+c^4+d^4) \space\leq48\space$$ ? What laptop specs are important for intensive image editing work? How important is the following in purchasing a laptop that will be used for image editing:   processor speed amount of RAM integrated vs. dedicated graphics card HD speed (SSD; or 5400/7200/10000 rpm) The 10th and last round of negotiations between Iran and the six world powers was held in Vienna in a bid to strike a final deal. However, after the sides failed to agree on a final deal they decided to extend the negotiations until / by July 1, 2015.   In the original text the preposition until has been written. I am, however, wondering if we could use by instead, if so, is there any difference semantically?  Any help would be greatly appreciated Proof that $S_3$ isomorphic to $D_3$ What is the difference between these two:     Suzuki was nearly close to go out of business just after the World War period.   Vs.     Suzuki was nearly close to going out of business just after the World War period.(from a video)   When talking about the past, do these two sentences different from each other? Like, if you use verbing(going) with infinitive(to) in the past, does it mean that there is another event happening? Or none. I am trying to setup a dual screen configuration on debian 8 jessie with Gnome.  My computer has 3 graphical outputs : 2 displayport and 1 HDMI. I can't manage to have two of this 3 outputs to work simultaneously.  output of xrandr is (with the other display on displayport):  xrandr: Failed to get size of gamma for output default Screen 0: minimum 1680 x 1050, current 1680 x 1050, maximum 1680 x 1050 default connected primary 1680x1050+0+0 0mm x 0mm 1680x1050      0.00* `   output of xrandr is (with hdmi working):  xrandr: Failed to get size of gamma for output default Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080 default connected primary 1920x1080+0+0 0mm x 0mm 1920x1080      0.00*   I also tried to use both displayport but it does not work either.  output of lshw -c videò:  *-display UNCLAIMED         description: VGA compatible controller    product: Intel Corporation    vendor: Intel Corporation    physical id: 2    bus info: pci@0000:00:02.0    version: 06    width: 64 bits    clock: 33MHz    capabilities: pciexpress msi pm vga_controller bus_master cap_list    configuration: latency=0    resources: memory:f6000000-f6ffffff memory:e0000000-efffffff  ioport:f000(size=64)   (with both screens connected via displayport)  output of lspci -v -s0:0:2.0  00:02.0 VGA compatible controller: Intel Corporation Device 1912 (rev 06) (prog-if 00 [VGA controller]) Subsystem: Dell Device 06b9 Flags: bus master, fast devsel, latency 0, IRQ 255 Memory at f6000000 (64-bit, non-prefetchable) [size=16M] Memory at e0000000 (64-bit, prefetchable) [size=256M] I/O ports at f000 [size=64] Expansion ROM at &lt;unassigned&gt; [disabled] Capabilities: &lt;access denied&gt; Comparing two Lists and returning the distinct values and the differences Deleting a comment (mine) shouldn't count as a comment vote Filtered Questions Asked By Accepted Answer/ No Accepted Answer I think it's helpful if we can go to a page and view all our own questions that   Does not have an accepted answer, and/or Does not have an answer yet.   The reason I asked for them is because, I sometimes need to review through all the questions, and pick those that don't have proper answers so that I can perform further operations on them ( such as offering a bounty, or accept an existing answer). Switching between windows with scroll wheel on Ubuntu Dock In the previous version the logout button is under your username, which it can be found by clicking the down arrow. However, in the new version, after a couple minutes of searching, it is under the "site-switcher" button:        This is really illogical since the logout button is usually under your username, including Google and Yahoo! services.  I suggest bringing back the  which will definitely benefit new users and even old users. Duplicate notifications I receive every push notification from the iOS app twice on iPhone. The second comes immediately after the first. This happens every single time.   I also have the app installed on an iPad and signed in to the same account - could this be a possible cause?   App Version: 1.4.0 Device: iPhone7,2 OS Version: Version 9.1 (Build 13B143) TeXnicCenter & Adobe Reader DC How to configure TeXnicCenter to work with Adobe Reader DC? When I building and view current file .tex the following error "Can not execute the command" shows up and the PDF is not generated.    If there are any related post, could help. Thanks a lot! In what order should the Star Wars movies be watched? Please don't lynch me, but I've never sat through an entire Star Wars film. I'm aware that the 3 (new) films are technically prequels, but I feel strange watching 3 new films then 3 old films?  Do I need to watch the new ones then the old ones? Who was/were the first Jedi? Force "portrait" orientation mode Redirect to SSL only if browser supports SNI I want to mount the device /dev/sda3 to the directory /foo/bar/baz. After mounting the directory should have the uid of user johndoe. So I did:  sudo -u johndoe mkdir /foo/bar/baz stat -c %U /foo/bar/baz johndoe   and added the following line to my /etc/fstab:  /dev/sda3 /foo/bar/baz ext4 noexec,noatime,auto,owner,nodev,nosuid,user 0 1   When I do now sudo -u johndoe mount /dev/sda3 the command stat -c %U /foo/bar/baz results in root rather than johndoe. What is the best way to mount this ext4-filesystem with uid johndoe set?