How to prevent my app from crashing when handling any error? I use a OnClickListener to execute a method this way :      b= (Button) findViewById(R.id.b);     b.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View v) {             if (on){                 try {sendData("b");} catch (IOException e) {e.printStackTrace();}             }             else {Toast.makeText(getApplicationContext(), "You should turn bluetooth on!", Toast.LENGTH_SHORT).show();}         }     });   sendData method :  public void sendData(String s) throws IOException {     try {         byte[] byteString = s.getBytes();         outputStream.write(byteString);         outputStream.flush();         Toast.makeText(getApplicationContext(), s + "sent", Toast.LENGTH_SHORT).show();     }catch (IOException e) {         Toast.makeText(getApplicationContext(), s + "not sent", Toast.LENGTH_SHORT).show();         e.printStackTrace();} }   this makes my app crashes if on = true     03-28 08:37:09.733 28841-28841/com.android.map.brasrobotique   E/AndroidRuntime: FATAL EXCEPTION: main                                                                                  Process: com.android.map.brasrobotique, PID: 28841                                                                                  java.lang.NullPointerException                                                                                      at   com.android.map.brasrobotique.MainActivity.sendData(MainActivity.java:221)                                                                                      at   com.android.map.brasrobotique.MainActivity$2.onClick(MainActivity.java:77)                                                                                      at android.view.View.performClick(View.java:4633)                                                                                      at android.view.View$PerformClick.run(View.java:19270)                                                                                      at android.os.Handler.handleCallback(Handler.java:733)                                                                                      at android.os.Handler.dispatchMessage(Handler.java:95)                                                                                      at android.os.Looper.loop(Looper.java:146)                                                                                      at android.app.ActivityThread.main(ActivityThread.java:5602)                                                                                      at java.lang.reflect.Method.invokeNative(Native Method)                                                                                      at java.lang.reflect.Method.invoke(Method.java:515)                                                                                      at   com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)                                                                                      at dalvik.system.NativeStart.main(Native Method)   how to prevent it from exiting?  thank you!
What is a NullPointerException, and how do I fix it? What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
Never delete entries? Good idea? Usual? Displaying mysql data in html table PHP A Basic Question about Gravity, Inertia or Momentum or something along those lines Distant aliens receive signal with instructions on how to construct humans, long after Earth is extinct In-universe explanation for single line of planetary entry/departure in Star Wars Why are planetary blockades confined to a single point of a planet instead of being sphere shell shaped around the planet? (I know, it would take an awful lot of spaceships.)  Also, when a rebel ship wants to escape from a planet and there is a single star destroyer hovering in the atmosphere (or some more of them further up, like in the Empire Strikes Back) how come it's not a viable maneuver to fly low altitude for a couple of hundred kilometers horizontally (they would be out of the single-point blockade), then make a vertical dash upwards? I would really love to play wizard/warlock multiclass with low charisma (just 13 for mutliclass). The handbook says that I can use Pact Magic slots to cast wizard spells, but doesn't specify which ability I use for spellcasting.     Pact Magic.   If you have both the Spellcasting class feature and the Pact Magic class feature from the warlock class, you can use the spell slots you gain from the Pact Magic feature to cast spells you know or have prepared from classes with the Spellcasting class feature, and [vice versa].   When I cast wizard spells using Pact Magic slots (or warlock spells using wizard's "Spellcasting" slots) do I use spellcasting ability of the slot, or do I get to choose? How do I reboot a Ubuntu Server from the command line? sudo reboot now never seems to work for me. Because its a server, I don't have a window manager installed, so I can't do it from a GUI (which always seems to work).    I've had the problem for years on different versions of the operating system. It happens in virtual machines and on real metal. The same problem exists with sudo shutdown now, too.  I've lived with it in the past. The difference now is I don't want to just hit the power button because I might lose data. Almost half of disk space unaccounted for on Windows 7 computer I'm trying to determine what's eating almost half of disk on my Windows 7 Lenovo laptop but haven't been able to determine what.  I read some of the answers on this site but none of the causes seems to be the cause of my problem.  What I've done so far:   Checked Windows' System Restore points but only minimum use, either way I deleted around 2GB if usage from there Used WinDirStat and it came back with a total of 71.3GB usage at the root level C Drives properties says 135GB being used out of 138 GB total, ie, 135 GB - 71.3GB = 63.7GB missing somewhere No "Unknown" files reported by WinDirStat Windows Disk Management utility doesn't report any unused partitions or unclaimed space chkdsk comes out clean Windows disk cleanup tool doesn't report anything big, just small stuff in the lower MB range Lenovo backup tool hasn't been used nor there is a folder for the backup images   Any idea on what to look at and/or do?  EDIT: some additional info... Why is cold fusion considered bogus? Cold fusion is being mentioned a lot lately because of some new setup that apparently works. This is an unverified claim.  See for example:         ( of that last link in the Wayback Machine, given frequent  from that page.)   While we should give the scientific community time to evaluate the set up and eventually replicate the results, there is undoubtedly some skepticism that cold fusion would work at all, because the claim is quite extraordinary.  In the past, after Fleischmann and Pons announced their cold fusion results, in perfectly good faith, they were proven wrong by subsequent experiments.  What are the experimental realities that make Fleischmann and Pons style cold fusions experiments easy to get wrong?  Would the same risks apply to this new set up? Aside from the repetitive appearance of the black cat, I can't remember seeing any living animals, either inside the Matrix simulation or in Zion.  How come? Is there an in-universe explanation? How to close entire application when application has more than 2 forms without showing messagebox more than once I am attempting to return an integer (itemcount) of the items within a SP2013 list. I have done this easily using the stock standard json method. However I have a need of counting the splist items which contain a certain value. My silly knowledge immediately lead me to try and use filtering with the ItemCount parameter only to find out that it will always still return the count for all items and it will completely ignore the filter. I have searched for a way of doing this but have found absolutely nothing other than a single page with a comment stating that it is not possible with the REST api and that it can ONLY be done using CSOM.  My question is, firstly, is it true that there is NO way to filter itemcount with REST? If so, how else can I obtain my item count using this type of filtering? (Examples or sources will help vastly) Thanks.  Below is my attempted request:  var itemid = item.id;           MyService.ensureFormDigest(function (fDigest) {               $http.get(                   MyService.appWebUrl + '/_api/web/Lists/getbytitle(\'Items\')/ItemCount?$filter=SubjectsID eq' + itemid,                   {                       headers: {                           'Accept': 'application/json; odata=verbose',                           'X-RequestDigest': fDigest                       }                   }).success(function (d) {                       item.itemcode = d.d.ItemCount;                       alert(item.itemcode);                       callback();                   }).error(function (er) {                       alert("Error getting List Item Count: " + er);                   });           });       }   On another note, I was advised to try it as such: /Items?$filter=SubjectsID eq 3&amp;$select=Id  Then in the JS, in my success method:  data.d.results.length How to find and delete identical points? I recently performed  on a merged point feature class in ArcGIS 10.1.  I specified "1 meter" XY tolerance for the Integrate command.  The resulting point feature appears to be what I want except points that were integrated are now stacked on top of each other, which will be problematic in future processing steps.  The attributes for my dataset consist of an OID, Shape, x, y, z.  Where x and y = UTM coordinates and z = buffer distance.  The command  does not appear to work for my dataset (i.e based on Fields: OID, Shape, x, y, z and XY tolerance = 1m) as the output still has stacked points.  I am also working with big data--the integrate output has 37 million points.    There is a related thread, titled , although I would like to open the question up to python solutions too.  What is the best way to find and delete (spatially) duplicate points?  Is there a better solution to integrating such that the output does not contain overlapping points? Attribute field names truncation when creating shapefiles I am wondering what is the expression that truncate a given name to the 10 characters name used in ESRI shapefiles when an object is saved as shapefile with the function writeOGR in R. For example, the attribute field from a spatial dataframe "Ablepharus kitaibelii" is converted to "Ablphrk" when saved as shapefile, how the truncation is done? Why do I need to type `./` before executing a program in the current directory? While executing a C program, a.out, using the Ubuntu terminal, why do I always need to type ./ before a.out, instead of just writing a.out? Is there solution for this? How to find "file-release" in OS X El Capitan 10.11.6? I can not find file-release through command line on OS X El Capitan Version 10.11.6. On my virtual machine in Ubuntu I can do "ls /etc/*release" and it shows me two files with all needed information:  $ cat /etc/redhat-release  Red Hat Enterprise Linux Server release 7.0 (Maipo)  $ cat /etc/os-release  NAME="Red Hat Enterprise Linux Server" VERSION="7.0 (Maipo)" ID="rhel" ID_LIKE="fedora" VERSION_ID="7.0" PRETTY_NAME="Red Hat Enterprise Linux Server 7.0 (Maipo)"   No idea how to find the file with release information on Mac. Please give me a hint or a hint how to search it? I am new to this and not sure what to make of all the options available. I am interested in putting a machine-learning-related preprint, which will potentially be submitted to places like NIPS/ICLR/ICML in the future.   arXiv.org perpetual, non-exclusive license to distribute this article (Minimal rights required by arXiv.org)  Creative Commons Attribution license (CC BY 4.0)  Creative Commons Attribution-ShareAlike license (CC BY-SA 4.0)  Creative Commons Attribution-Noncommercial-ShareAlike license (CC BY-NC-SA 4.0)  Creative Commons Public Domain Declaration (CC0 1.0) I need to start by stating that I have read through every single problem on here relating to mine, but all of them seem to have access somehow to their server's files. I do not, so here is my question.  I'm on centOS 6.5 and ssh closes connection right after a successful login. I am using mac and windows/putty to access my server with the same results. Is there anyway I can access my server now without having access to its files?   Below is the readout from ssh -vvv right after a successful login:  debug1: Authentication succeeded (password). Authenticated to 4X.5X.XX.2 ([4X.5X.XX.2]:82). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting no-more-sessions@openssh.com debug1: Entering interactive session. debug2: callback start debug2: fd 3 setting TCP_NODELAY debug3: ssh_packet_set_tos: set IP_TOS 0x10 debug2: client_session2_setup: id 0 debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env TERM_PROGRAM debug3: Ignored env SHELL debug3: Ignored env TERM debug3: Ignored env TMPDIR debug3: Ignored env Apple_PubSub_Socket_Render debug3: Ignored env TERM_PROGRAM_VERSION debug3: Ignored env TERM_SESSION_ID debug3: Ignored env USER debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env __CF_USER_TEXT_ENCODING debug3: Ignored env PATH debug3: Ignored env PWD debug1: Sending env LANG = en_US.UTF-8 debug2: channel 0: request env confirm 0 debug3: Ignored env XPC_FLAGS debug3: Ignored env XPC_SERVICE_NAME debug3: Ignored env SHLVL debug3: Ignored env HOME debug3: Ignored env LOGNAME debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 debug2: channel_input_status_confirm: type 99 id 0 debug2: PTY allocation request accepted on channel 0 debug2: channel 0: rcvd adjust 2097152 debug2: channel_input_status_confirm: type 99 id 0 debug2: shell request accepted on channel 0 Last login: Wed Oct  7 06:23:21 2015 from 1XX.XXX.X1.185 debug1: client_input_channel_req: channel 0 rtype exit-status reply 0 debug1: client_input_channel_req: channel 0 rtype eow@openssh.com reply 0 debug2: channel 0: rcvd eow debug2: channel 0: close_read debug2: channel 0: input open -&gt; closed debug2: channel 0: rcvd eof debug2: channel 0: output open -&gt; drain debug2: channel 0: obuf empty debug2: channel 0: close_write debug2: channel 0: output drain -&gt; closed debug2: channel 0: rcvd close debug3: channel 0: will not send data after close debug2: channel 0: almost dead debug2: channel 0: gc: notify user debug2: channel 0: gc: user detached debug2: channel 0: send close debug2: channel 0: is dead debug2: channel 0: garbage collecting debug1: channel 0: free: client-session, nchannels 1 debug3: channel 0: status: The following connections are open:   #0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cc -1)  Connection to 4X.5X.XX.2 closed. Transferred: sent 3176, received 2640 bytes, in 0.3 seconds Bytes per second: sent 10370.6, received 8620.4 debug1: Exit status 254 $P(\limsup A_n)=1 $ if $\forall A \in \mathfrak{F}$ s.t. $\sum_{n=1}^{\infty} P(A \cap A_n) = \infty$ Let $\mathfrak{F} = (A_n)_{n \in \mathbb{N}}$. Prove that $P(\limsup A_n)=1$ if $\forall A \in \mathfrak{F}$ s.t. $P(A) &gt; 0, \sum_{n=1}^{\infty} P(A \cap A_n) = \infty$. (Side question 1 Is second Borel-Cantelli out because we don't know if the $A_n$'s are independent?)  Suppose $\forall A \in \mathfrak{F}$ s.t. $P(A) &gt; 0, \sum_{n=1}^{\infty} P(A \cap A_n) = \infty$, but $P(\limsup A_n)&lt;1$. My prof gave us this convenient hint: Show $\exists M &gt; 0$ s.t. $P(\bigcap_{j=M}^{\infty} A_j^{c}) &gt; 0$.  $1 &gt; P(\limsup A_n)$  $1 - P(\limsup A_n) &gt; 0$  $P(\liminf A_n^{c}) &gt; 0$  By definition of $\liminf A_n^{c}$, $\exists M &gt; 0 $ s.t. $P(\bigcap_{j=M}^{\infty} A_j^{c}) &gt; 0$. (Side questions 2 and 3 Isn't this =1? ...Wait, is that what we're trying to prove? Haha)  $\to 1 - P(\bigcup_{j=M}^{\infty} A_j) &gt; 0$  $\to 1 &gt; P(\bigcup_{j=M}^{\infty} A_j)$  Main question: Now I guess we have to come up with some A s.t.  $\to 1 &gt; P(\bigcup_{j=M}^{\infty} A_j) \geq \sum_{n=1}^{\infty} P(A \cap A_n)$, or is there something else to do? How to measure capacitance without LC meter? I would like to use capacitors salvaged from old electronics, but I currently don't have an LC meter.    What would be some really simple circuits, that would convert capacitance to something I can measure (voltage, current, frequency)?