Java programming assignment newly learned stuff

1) Hashmap:

Simple example: https://beginnersbook.com/2013/12/hashmap-in-java-with-example/

Best way to iterate items: https://stackoverflow.com/questions/1066589/iterate-through-a-hashmap

Convert a string to 8-bit ascii: https://stackoverflow.com/questions/33864306/how-to-convert-a-string-into-8-bit-ascii-in-java

最后用的直接查表。。很直观也很简洁，是好方法。

小编程题练了字符串解析和ha sh ma p