Gangmax Blog


Jigsaw: The Java Standard Module System

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Jigsaw is the Java standard module system released with JDK 9. The whole JDK 9 is reorganized with Jigsaw. That means after JDK 9, you will not find the huge “rt.jar” file in the JDK directory, instead a “$JDK_PATH/jmods” directory full of “*.jmob” files is introduced and all the files in it are the module files.

eBook Format Mobi to Epub

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If you have a “mobi” format eBook file and want to convert it to “epub” format like me, you can use the software “Calibre” to do it, which is available on Linux/Mac/Windows.

For Ubuntu, run the following commands to install Calibre and convert the format.

sudo apt-get intall calibre
ebook-convert your_ebook.epub

There are also online services which can do the same thing like here. You can use such services if you don’t want to install a software to do it.

VirtualBox Error ‘NS_ERROR_FAILURE (0x80004005)’

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Yesterday I got the “NS_ERROR_FAILURE (0x80004005)” error when starting a VM instance in VirtualBox. Reinstalling didn’t work and the error was still there. The real problem is the security permission. Go to “System Preferences -> Security & Privacy”, confirm the permission needed by VirtualBox, then the problem is solved.