Since java 8 you can just do
Set<String[]> collect = Files.lines(Paths.get("/Users/me/file.txt"))
.map(line -> line.split(" ", 2))
.collect(Collectors.toSet());
if you want a map, you can just replace the Collectors.toSet by Collectors.toMap()
Map<String, String> result = Files.lines(Paths.get("/Users/me/file.txt"))
.map(line -> line.split(" ", 2))
.map(Arrays::asList)
.collect(Collectors.toMap(list -> list.get(0), list -> list.get(1)));