java.lang.NullPointerException: Attempt to invoke virtual method 'android.graphics.Bitmap android.graphics.drawable.BitmapDrawable.getBitmap()' on a null object refe app/xmpp/recv/handle_unavailable 0166@s.whatsapp.net null last:0
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?
How to use z-index in svg elements? Scenario  I created a journey with a Contact Data entry event that is triggered via the API. A subscriber should be able to be injected multiple times and the values in the data extension are updated while the subscriber is in the journey. The updated values should determine the path the subscriber follows.  Setup  As changed data needs to be evaluated and the contactkey cannot be used as primary key, I added a random id as primary key and created an attribute group for the data extension in Data Designer. The data extension is linked to the contact's contactkey using a one-to-many relationship as a contact should be able to enter the journey multiple times.  In the journey I'm using a decision split that is configured to use contact data from the created attribute group and has two branches (as it checks a boolean value).  Problem  For multiple entries the decision split doesn't evaluate correctly and always leads to same branch (value equals false). I suppose the problem is that journey builder doesn't use the primary key to identify the correct row in the data extension. Is there any way to make sure the row is matched using this id and not the contactkey as this leads to some strange behaviour as described here: Pokemon Go Supported Devices Arduino Negative Voltage Reading with Positive Ground I am trying to measure voltage &amp; current off a solar charge controller from panel, battery &amp; load simultaneously with my arduino. I have managed to achieve this by tying all the negatives together and using it as GND, however, when I do that the charge controller doesn't function properly and when I switch to off-mode the loads still run. After checking the instruction manual further, I found out that the positives are shared common between Pan, Bat, Load. This was confirmed with a multimeter.   So now what I am thinking of doing is using the positive from the battery as the GND reference and then measuring all other voltages (through voltage dividers with respect to the GND). The voltages should then range between -17V to 0V.   However, I have read that the analog input pins are not able to read negative voltages, and with respect to the positive GND, the Analog inputs will all be negative.   EDIT: I was thinking of using an amplifier to invert positive ground to a negative ground, meaning I could measure all the positive sides of the voltages. But after getting answers from you guys it seems I may not have to use an amplifier and a voltage divider may suffice. I have currently included a 2 resistor voltage divider between each analog input, +5V source, Vmeasure which you can see in the diagram below.  According to my calculations, if this works, @-17V I should see 0.6V @ analog input. @0V I should see 4V at analog input.   I'd appreciate feedback on this circuit, and below in the second image I've also included a piece of another method suggested by @jonk (thanks), and would be interested in knowing what the benefits are of method B) over method A)  Thanks!  Ps. the ameters are there in place of ACS712 current sensors which also go into analog input pins.   Method A)        &ndash; Schematic created using   Method B (EDIT: This method has worked, I am still yet to test method A) thanks @Jonk)) Using Ubuntu 12.04. is there any way to hide a running process ?  That process shouldn't' display in system monitor,top,htop . There is no problem to remember the process id (PID) so observation of the process can be done easily .but i want to hide the process completely . is there any way ? Is there a way to choose a beginning and ending edge and auto select all the edges in between? I have been using Blender for quite a long time and I just want to make sure that there isn't a better way of selecting edges, that I might not be aware of. It is so cumbersome to have to click every single edge when I don't want to select an entire edge loop but a portion of one instead. I was wondering if there is some way in to specify a start edge and an end edge and then be able to auto select every edge in between? How do malloc() and free() work? How to measure GPU usage? How can I install a Nautilus script? Command-line to switch between profiles in gnome-terminal I created a new profile for gnome-terminal and I can switch between &quot;Implicit&quot; profile and the new created profile as you can see in the below image:  Now I wonder how can I switch between profiles using a command-line/script or maybe using a shortcut for this.  Note: Solutions like: gnome-terminal --tab-with-profile=Implicit &amp;&amp; exit   are excluded because I prefer not to close and open another terminal or get another terminal window in this process of changing the profile. How can I communicate with a Unix domain socket via the shell on Debian Squeeze? I’m running a Debian Squeeze web server. I’ve installed memcached on it, and configured memcached to listen on a Unix domain socket (at /tmp/memcached.sock), as it only needs to receive messages from the website, which lives on the same server.  It seems to be working fine, but I’d also like to communicate with memcached via the shell, to check that it’s doing what I think it’s doing.  memcached accepts messages via a simple ASCII protocol (if I understand correctly). If it was listening on TCP/IP, I could send messages to it via e.g. nc:  $ echo "stats settings" | nc localhost 11211   But I can’t figure out how to send that text to the domain socket instead.  On my laptop (which runs OS X Lion), both nc and telnet have options (-U and -u respectively) to use domain sockets. However, on my Debian Squeeze web server, these options aren’t present. I have always heard the term used in referring to a single word. When browsing questions on this site, I've seen it used applied to entire phrases, and have suppressed the compulsion to edit them and replace the term with origin. Normality of dependent variable = normality of residuals? This issue seems to rear its ugly head all the time, and I'm trying to decapitate it for my own understanding of statistics (and sanity!).   The assumptions of general linear models (t-test, ANOVA, regression etc.) include the "assumption of normality", but I have found this is rarely described clearly.   I often come across statistics textbooks / manuals / etc. simply stating that the "assumption of normality" applies to each group (i.e., categorical X variables), and we should we examining departures from normality for each group.   Questions:     does the assumption refer to the values of Y or the residuals of Y?  for a particular group, is it possible to have a strongly non-normal distribution of Y values (e.g., skewed) BUT an approximately (or at least more normal) distribution of residuals of Y?   Other sources describe that the assumption pertains to the residuals of the model (in cases where there are groups, e.g. t-tests / ANOVA), and we should be examining departures of normality of these residuals (i.e., only one Q-Q plot/test to run).  does normality of residuals for the model imply normality of residuals for the groups? In other words, should we just examine the model residuals (contrary to instructions in many texts)?  To put this in a context, consider this hypothetical example:   I want to compare tree height (Y) between two populations (X).   In one population the distribution of Y is strongly right-skewed (i.e., most trees short, very few tall), while the other is virtually normal  Height is higher overall in the normally distributed population (suggesting there may be a 'real' difference). Transformation of the data does not substantially improve the distribution of the first    population.  Firstly, is it valid to compare the groups given the radically different height distributions? How do I approach the "assumption of normality" here? Recall height in one population is not normally distributed. Do I examine residuals for both populations separately OR residuals for the model (t-test)?     Please refer to questions by number in replies, experience has shown me people get lost or sidetracked easily (especially me!). Keep in mind I am not a statistician; though I have a reasonably conceptual (i.e., not technical!) understanding of statistics.  P.S., I have searched the archives and read the following threads which have not cemented my understanding: How to get the Duke O' Death? I was watching some videos on YouTube showing how to get the Duke O' Death in GTA 5, however what I have seen is sort of unclear.  Some people say you must be a returning player on GTA 5 to get it (what does this mean too BTW?), some people don't say that. Some people say you have to be Trevor, some people don't. Some say the time of day matters, some don't. And apparently you can buy it from Warstock website (I can't).   Can someone please tell me how to get it?! GTA 5 came with my PS4 (I didn't play it on PS3) if that helps. If $A|B$ and $B|A$ then prove $A=\pm B$ If $A|B$ and $B|A$ then prove $A=\pm B$   So far I have $A|B \iff AX=B$ and $B|A \iff BY=A$ with $X,Y \in \mathbb{Z}$  Not sure how to finish, any help. What is the appropriate public key encryption for secure coin flipping? I quote Bobby's question here since I encountered the same one...    Consider the following protocol for two parties to flip a fair coin.   Trusted party $T$ publishes her public key $K_{pub}$ $A$ chooses a random bit $b_A$, encrypts it under $K_{pub}$, and announces the ciphertext $c_A$ to $B$ and $T$ $B$ does the same and announces a ciphertext $c_B$ (where $c_B \neq c_A$) $T$ decrypts $c_A$ and $c_B$, and announces the results. Both parties $XOR$ the results to obtain the random value $b_A\oplus b_B$.   It was shown that  was not appropriate for the encryption scheme.  seems to fail to work also. Since $c_A=m^e \mod N$. Then if $m=1$, $c=1$. If $B$ receives $A$'s cipher he will know the exact value of $m$.   So what should the appropriate encryption scheme be? Will Determinism be ever possible? What is the difference between “say” and “tell”? I really get confused when to use say and when to use tell. Which is appropriate in the following:   What did he tell? / What did he say? What are you saying? / What are you telling? Install Headers on Kali apt-get install linux-headers-`uname -r` Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package linux-headers-4.9.0-kali3-amd64 E: Couldn't find any package by glob 'linux-headers-4.9.0-kali3-amd64' E: Couldn't find any package by regex 'linux-headers-4.9.0-kali3-amd64' I have a quite wide monitor and it's quite annoying to see the login dialog in the login screen on the far left side of my screen. I literally have to turn my head around to look at it!  Is there a way to center the login dialog?