2011-04-26 : init helloworld 2013-04-24 : add Java Inversion of Control (a.k.a IOC)demo. project test : this is for illustration purposes should not be treated as a best practice. project HelloSpring : an IOC demo by STS. 2013-05-14 : review the codes, modify the code structure, add new project: project : exuberant_ctags_test. instruction: compile : javac -d . Test.java run : java yummy.test.Test 2018-01-24 : start ML. 2018-01-25 : change /usr/local/lib/python3.5/site-packages/matplotlib/mpl-data/matplotlibrc 's line 40, "backend : agg" -> "backend : TkAgg" , so we can see image immediately.