Java 8 lambda expression for list/array conversion
1). Convert List
List<Integer>
// 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)
String[] stringArray = Arrays.stream(intArray).mapToObj(Integer::toString).toArray(String[]::new);
7). Convert 2D int[][] to List
- > ( 2D int array to nested Integer List)
List<Integer> list = Arrays.stream(dataSet).map(Arrays::asList).collect(Collectors.toList());
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