如何使用收集器而不是手动放入java 8中的ConcurrentHashMap

Question

How can I Use Collectors to collect in a ConcurrentHashMap instread of putting manually into ConcurrentHashMap

ConcurrentHashMap<String, String> configurationMap = new ConcurrentHashMap<>();
List<Result> results = result.getResults();
results.stream().forEach(res -> {
     res.getSeries().stream().forEach(series -> {
         series.getValues().stream().forEach(vals ->{
                 configurationMap.put(vals.get(1).toString(),vals.get(2).toString());
         });
     });
});

//Note: vals is List<List<Object>> type

Help will be appreciated.

Answer 1

You can use Collectors.toConcurrentMap

results.stream()
           .flatMap(res -> res.getSeries().stream())
           .flatMap(series -> series.getValues().stream())
           .collect(Collectors.toConcurrentMap(
                                  vals -> vals.get(1).toString(),
                                  vals -> vals.get(2).toString()));

Answer 2

We can do this as follows also:

results.stream()
       .flatMap(res -> res.getSeries().stream())
       .flatMap(series -> series.getValues().stream())
       .collect(Collectors.toMap(
                              vals -> vals.get(1).toString(),
                              vals -> vals.get(2).toString(),
                              (vals1,vals2) -> vals2,
                              ConcurrentHashMap::new);