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Showing posts from August, 2017

Java 8 lambda expression for list/array conversion

1). Convert List to List ( List of Strings to List of Integers)

List<Integer>  integerList = stringList.stream().map(Integer::parseInt).collect(Collectors.toList()); 

// the longer full lambda version:  List<Integer>  integerList  = stringList.stream().map(s -> Integer.parseInt(s)).collect(Collectors.toList());

2). Convert List to int[](List of Strings to int array)
int[] intArray = stringList.stream().mapToInt(Integer::parseInt).toArray();

3). Convert String[] to List ( String array to List of Integers)
List<Integer>  integerList = Stream.of(array).map(Integer::parseInt).collect(Collectors.toList());

4). Convert String[] to int[] (String array to int array)
int[] intArray = Stream.of(stringArray).mapToInt(Integer::parseInt).toArray();
5). Convert String[] to List (String array to Double List)
List<Double> doubleList = Stream.of(stringArray).map(Double::parseDouble).collect(Collectors.toList());
6). Convert int[] to String[] (int array to String array)
Strin…