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If I have a List<List<Object>>, how can I turn that into a List<Object> that contains all the objects in the same iteration order by using the features of Java 8?
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Given below is the simplest way to create a list of lists in Java: For String: List<List<String>> listOfLists = new ArrayList<>(); That's it.
Another approach to copying elements is using the addAll method: List<Integer> copy = new ArrayList<>(); copy. addAll(list); It's important to keep in mind whenever using this method that, as with the constructor, the contents of both lists will reference the same objects.
Using List.You can declare a List of Lists in Java, using the following syntax. It uses the new operator to instantiate the list by allocating memory and returning a reference to that memory. To add elements to it, call the add() method.
flatMap() method. The standard solution is to use the Stream. flatMap() method to flatten a List of Lists. The flatMap() method applies the specified mapping function to each element of the stream and flattens it.
You can use flatMap to flatten the internal lists (after converting them to Streams) into a single Stream, and then collect the result into a list:
List<List<Object>> list = ... List<Object> flat = list.stream() .flatMap(List::stream) .collect(Collectors.toList()); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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