So problem file requests to "populate the properties map with data from the file. You can read about .properties here:". However, after done reading wiki page, all I know is that `.properties` is a file suffix .properties with key, value pairs, and even the key, value pairs can be various :
Several formats are possible for each line, including key=value, key = value, key:value, and key value
It seems that I need to create a FileInputStream reading console input and that input should be key-value pairs to construct .properties ? but where is this .properties from ? Totally lost. Thank you guys!