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...

   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...