I want to convert some file format into Java Map.
My team uses some specific file format like below.
[[("name", "Mike"), ("age", 10), ("gender", "M")], [("name", Mary), ... ]]
First, I'll say that the data file format would probably have been better off in XML, which is intended for structured data. That doesn't exactly solve your problem with this data file, though it might be helpful for the future; JSON is another option as that's also a well-known data format.
As far as for this file, Files.lines() breaks an input file into a Stream, but then you'd have to process the Stream by groups of four items. Streams are supposed to be parallelizable, and your particular need doesn't lend itself well to that.
If you're intending to use this file as a flat-file database, it would probably be better in the long run to write one program to permanently translate it to a structured format like XML or JSON, and another module to access the XML or JSON data via streams.