Attempt to invoke virtual method 'java.util.ArrayList com.example.news.ResponseModel.getArticles_lists()' on a null object reference
What is a NullPointerException, and how do I fix it?
How to build a single virtual machine on top of multiple computers? Is there a way to run Linux operating system on a virtual machine which aggregates the resources of physical machines on the local network and acts as a single super-computer? If possible, how?  Thanks. Pokemon Go: Can't log in? Are everyone unable to log in right now? 2016 July 16. Where I live none can log in to the servers at the moment, and it all happened after the sudden release of the game in my country.   As I understand the game was recently released in 26 countries, so I guess they have problems and had the servers go offline in order to fix the issues. CSS :after not adding content to certain elements Define a mathematical set How to change IP address to point to localhost? Solution for A/C Condensate Drain Line that doesn't require emptying a bucket of water every day? Is it possible to install an old version of Mac OS on a new Mac? Possible Duplicate:          Is there anywhere or anyone to complain to about the behaviour of moderators? I've been "spoken" to offensively by a moderator, and I'm unhappy about it. Why does println(array) have strange output? ("[Ljava.lang.String;@3e25a5") My account has been temporarily suspended; what does that mean? My account has been , besides the following restrictions:  an account will be locked at 1 reputation the user page will have a visual indication that the account is in timed suspension, and for how long the account holder will be unable to vote, ask, answer or comment  What else does timed suspension prevent me doing? For example, can I still edit my own posts or delete content? And what is a network-wide suspension? Scenario: I have a custom button on a standard layout, which will call an apex class to do some validation on a record. If not validated, it needs to throw out some errors on that page. What are the best UX options to achieve this?  I am not too sure how to achieve this. Within a trigger, you can use the addError method to add the custom errors.  Can my Apex class reference the fields of a standard object? The ideal approach would be to do the following:  Contact.Email.addError('Please enter the right format here');   How can I achieve this via an apex class that the custom button will call?  What I have thought: Having a VF Page popup on the screen so that user can see all the errors, but that's not the best approach as UX is a big deal for this application  Thanks. What is the volatile keyword useful for? At work today, I came across the volatile keyword in Java. Not being very familiar with it, I found . Given the detail in which that article explains the keyword in question, do you ever use it or could you ever see a case in which you could use this keyword in the correct manner? Capturing URL parameters in request.GET I am currently defining regular expressions in order to capture parameters in a URL, as described in the tutorial. How do I access parameters from the URL as part the HttpRequest object? My HttpRequest.GET currently returns an empty QueryDict object. I'd like to learn how to do this without a library, so I can get to know Django better. How quickly is antibiotic resistance lost? Honestly, navigation through Area 51 is a bit confusing and seems to be much different from the other SE sites.    The feature that is very lacking is the footer with all the sites you are subscribed to so that a user can easily return to a different SE site. This one really bugs me.  Can this be easily fixed?  Also, unlike all the other sites there is no "meta" site to add comments specifically about that site.    Again Area 51 seems out of sync with the other SE sites. Why does Beamer not change the itemize symbol when using \setbeamertemplate? This code:  \documentclass[10pt]{beamer} \setbeamertemplate{itemize item}[circle] \setbeamertemplate{itemize subitem}[triangle] \setbeamertemplate{itemize subsubitem}[square]   \begin{document} \begin{frame} \begin{itemize} \item first level     \begin{itemize}     \item second level         \begin{itemize}         \item third level         \end{itemize}     \end{itemize} \end{itemize} \end{frame} \end{document}    produces this output:    I expected the symbol of the first level item to be a circle, not a square. Is there an error in my code? The log file was too long to include in the question, so I . Is it possible to use Boot Camp with Windows 10 from an external HDD? I need to run Visual Studio on my MacBook Pro and I need Windows to do that. The easiest and well known way to install Windows on a Mac is by running the Boot Camp app on the Mac and let it do what's necessary. The problem is that I don't want to partition the Internal SSD so the remaining option is to install Boot Camp Windows 10 on an External Drive and boot it every time I need it by plugging in my external USB 3.0 HDD. Is this achievable? How to set default style for arrow tips in TikZ? How does Java's PreparedStatement work? I am planning to replace repeatedly executed Statement objects with PreparedStatement objects to improve performance. I am using arguments like the MySQL function now(), and string variables.   Most of the PreparedStatement queries I have seen contained constant values (like 10, and strings like "New York") as arguments used for the ? in the queries. How would I go about using functions like now(), and variables as arguments? Is it necessary to use the ?s in the queries instead of actual values? I am quite confounded. Pre-generate Review audits to avoid the lag?