Convert List of List into list in java

superlist.forEach(e -> result.addAll(e));

Now after some reasarch, I found this way.

Try like this using flatMap:

List<List<Object>> list = 
List<Object> lst = list.stream()
        .flatMap(Collection::stream)
        .collect(Collectors.toList());

If you're on Java < 8 (and cannot use Streams), you can do this in a one-liner with Guava's Iterables.concat:

List<String> merged = Lists.newArrayList(Iterables.concat(superList));

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