Developer Tech Blog

 When just running some program which downloaded from site or just click applications I got, sometimes we face an error window with 'java.lang.NullPointerException'. This error window caused by 3 kinds of reason. First, Application needs Configuration File to run with.  Many Program has configuration file to run the application. Configuration file extensions are variable like '.ini', '.yaml', '.config', '.txt', etc... Somehow if you erase the configuration file or copied the application.exe to other folder without the configuration file. This could cause NullPointerException. Second, Application Needs Parameter(s) to run.  Some application needs parameter to run. When your program start or do something with UI, there could be selection to do. But without selection, your program could throw NullPointerException. So, you can check application guide what should you missed to check in checkbox or select files or other things in application. Third, Ap...

 When we programming with java, we can see 'java.lang.NullPointerException' error often. NullPointerException is kinds of RuntimeException.  This error occurs as a Java program attempts to use a null when an object is required. Let's see what this means.          Integer   invalid_intObject  =  null ;          System . out . println ( invalid_intObject . intValue ());  This codes makes NullPointerException because invalid_intObject is object but it's null. Below is valid code.            Integer   invalid_intObject  =  0 ;          System . out . println ( invalid_intObject . intValue ());  But in real programming world, this is not that simple to debug. So, what's in real programming world? we always call functions that we did not make...

It was released in May 2020 release and updated in September 2020 release. Eclipse doesn't have this functionality at this time.   When I program something with many files, I really need this function. Most editors has 'close Others', 'close to the right' options. But with this pin file and 'close All', I could manage opened files easily. See below Introduce on September 2020 release. Pinned tabs also show a new "pinned" icon to allow you to unpin with one click. This icon will also appear in the "Open Editors" view. Theme:  GitHub Light Also they added compact options for editor tabs. A new setting  workbench.editor.pinnedTabSizing  allows you to configure how large a pinned tab should appear: normal : a pinned tab inherits the look of other tabs (new default) shrink : a pinned tab shrinks to a fixed size showing parts of the editor label compact : a pinned tab will only show as icon or first letter of the ed...

    There are two famous beautify code plugins for Front-end developers in Visual Studio Code. So, I'd like to compare what plugin is better to use for me.   The plugins are First, Prettier Second, Beautify. As you can see, Prettier is more popular than Beautify and Prettier supports more languages than Beautify.  Prettier  Install count: 8,628,031 language support:  JavaScript · TypeScript · Flow · JSX · JSON CSS · SCSS · Less HTML · Vue · Angular GraphQL · Markdown · YAML Beautify  Install count: 5,510,943 language support:  javascript, JSON, CSS, Sass, and HTML Prettier has more strict options users should use while Beautify let users do more free way. But I'd like to use Prettier for now because I don't need free style and Prettier supports more langua...

   Visual Studio Code is very popular for developers and Java is the most popular programming language in present world.  So in this article, I will show how to set up Visual Studio Code for java in Windows 10 very easily.  VS Code Team released Visual Studio Code with JDK. This is very cool because installing JDK need some configurations but in this download link that kinds of uncomfortable process removed. (downlaod jdk and install / configure environment / configure visual studio code) Let's see how comfortable it is. Download and Install Visual Studio Code for Java Click  Download and Install the Coding Pack for Java - Windows via this link Install Coding Pack for Java Installing Components Finished Setup Wizard Now you can see Lau...

   When installing Eclipse and spring tools for plugin, you can see there's no auto completion for annotations  like @Autowired.. Problem: By default, eclipse doen't auto complete for annotations like @Autowired, @PostMapping...   Resolution: Eclipse java has only auto complete (activate) for  '.' we should add '@' character for auto completion How To Solve Windows > Preferences > Java > Editor > Content Assist  Check Enable auto activation Add @ to triggers Auto activation triggers for Java: .@  Click Apply and Close Let's see If Auto Activation works or not. Done! If you have other languages like php, javascript, etc in eclipse, same process applies for triggering activation in editor. Reference: https://www.eclipse.org/pdt/help/html/using_javascript_content_assist.htm ...

   Sometimes eclipse cannot connect to marketplace or plugin sites for installing plugins because of security validator exception Problem: sun.security.validator.ValidatorException or sun.security.validator.ValidatorException: PKIX path building failed   Resolution: tuststore does not contain the certificate of the SSL service you're connecting to This is due to corporate environments where your workstation is intercepted by proxy, firewall or something that inspects https traffic. or the jdk version does not include the SSL service you're connecting to. jdk release with certificates in the jre/lib/security/cacerts file. the certificates are increase while jdk version goes up How To Solve Download  Keystore Explorer  and Install Open the application (Run as administrator) Examine > Examine SSL > Co...