How to check the JDK version of a class file
When running a Java application it is mandatory that the JRE version to match or to be higher that the JDK version used to compile the application.
You will get the "Unsupported major.minor version 52.0" error when trying to run an Java 1.8 application using a lower version of Java.
Abstract keyword in Java
The abstract keyword is used in Java for abstraction. The abstraction is the process of selecting data and displaying only the relevant details to the object. If helps to reduce the programing complexity and the efort.
All keywords in Java
Keywords are special words in the programing language which have reserved use in the language. Keywords may not be used as identifiers in Java; for example you cannot declare a field whose name is a keyword.
How to fix apt lock-frontend error in Ubuntu
How to fix the E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable) error.
How to delete the Windows.old folder from Windows 10
If you recently update your OS to Windows 10, you might notice that you are running out of space. If this is happening it might be because the old version of the Windows is not yet deleted from the disk, it is stored into "Windows.old" folder. And depending on the size of that version, it could be taking a lot of precious space.
How to change DNS settings from command line
The command line tool used to change the DNS settings is netsh which allows you to configure just about any aspect of your network connections in Windows. In order to use the tool the command line needs to be started as Administrator.
