Java Streams

Streams in java are somewhat like iterators, in that they provide an-element-at-a-time interface.

However, they can also be processed in parallel.

And operations like filter, map, reduce, collect can be applied.

Below is a example of how the code can be really succinct.
We read a text file, and group by the first column, producing counts per group in a few lines:

Map mresult = Files.readAllLines( Paths.get("/home/test/testaccess.log")).stream()
            .map( line-> line.substring(0, line.indexOf(" ") ) )
            .collect( Collectors.groupingBy( line->line, Collectors.counting()) );
        System.out.println( mresult);