Is there a better functional way of converting an array of Strings in the form of "key:value" to a Map
using the Java 8 lambda syntax?
Arrays.asList("a:1.0", "b:2.0", "c:3.0") .stream() .map(elem -> elem.split(":") .collect(Collectors.toMap(keyMapper?, valueMapper?));
The solution I have right now does not seem really functional:
Map<String, Double> kvs = new HashMap<>(); Arrays.asList("a:1.0", "b:2.0", "c:3.0") .stream() .map(elem -> elem.split(":")) .forEach(elem -> kvs.put(elem[0], Double.parseDouble(elem[1])));
You can modify your solution to collect the Stream
of String
arrays into a Map
(instead of using forEach
) :
Map<String, Double> kvs = Arrays.asList("a:1.0", "b:2.0", "c:3.0") .stream() .map(elem -> elem.split(":")) .collect(Collectors.toMap(e -> e[0], e -> Double.parseDouble(e[1])));
Of course this solution has no protection against invalid input. Perhaps you should add a filter just in case the split String has no separator :
Map<String, Double> kvs = Arrays.asList("a:1.0", "b:2.0", "c:3.0") .stream() .map(elem -> elem.split(":")) .filter(elem -> elem.length==2) .collect(Collectors.toMap(e -> e[0], e -> Double.parseDouble(e[1])));
This still doesn't protect you against all invalid inputs (for example "c:3r"
would cause NumberFormatException
to be thrown by parseDouble
).
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