Occasionally in the development process needs to be int [] turn into a List <Integer>, using a traverse way too many to write code.
1 List<Integer> list = new ArrayList<>(); 2 for(int i : ints1){ 3 list.add(i); 4 }
Jdk1.8 using new features can get line of code, code simple
1 int[] ints = {1, 4, 5, 6}; 2 List<Integer> collect = Arrays.stream(ints).boxed().collect(Collectors.toList());
Compiled under jdk1.8 list <Integer>, Integer [], int [] conversions between the three
1 List<Integer> list = new ArrayList<>(); 2 list.add(111); 3 // List<Integer> -> int[] 4 int[] ints = list.stream().mapToInt(Integer::valueOf).toArray(); 5 System.out.println(ints.length); 6 7 // List<Integer> -> Integer[] 8 Integer[] integers1 = list.toArray(new Integer[0]); 9 10 // int[] -> List<Integer> 11 List<Integer> collect = Arrays.stream(ints).boxed().collect(Collectors.toList()); 12 System.out.println(collect.size()); 13 14 // int[] -> Integer[] 15 Integer[] integers = Arrays.stream(ints).boxed().toArray(Integer[]::new); 16 17 //Integer[] -> int[] 18 int[] ints1 = Arrays.stream(integers1).mapToInt(Integer::valueOf).toArray(); 19 20 //Integer[] -> list<Integer> 21 List<Integer> integers2 = new ArrayList<>(Arrays.asList(integers1));
Similarly, other similar package type
We hope to help readers see this blog post.