Some Memos - tenji/ks GitHub Wiki

备忘录

Java 16 之前：

int[] ints = {1, 2, 3};
List<Integer> list = Arrays.stream(ints).boxed().collect(Collectors.toList());

Java 16 之后：

List<Integer> list = Arrays.stream(ints).boxed().toList();

List<Integer> list = Arrays.asList(1, 2);
int[] ints = list.stream().mapToInt(Integer::intValue).toArray();

List<Integer> list = new ArrayList<Integer>(){{
    add(1);
    add(2);
}};

List<Integer> list = Arrays.asList(1, 2);

int[] ints = {1, 2, 3};
System.out.println(Arrays.toString(ints));

int[] ints = {1, 2, 3};
Arrays.stream(ints).sum();

int[] matrix = {{1, 2, 3}, {4, 5, 6}};
Arrays.deepToString(matrix);

使用 System 类：

int[] array = {23, 43, 55};
int[] copiedArray = new int[3];

System.arraycopy(array, 0, copiedArray, 0, 3);

或者使用 Arrays 类：

int[] array = {23, 43, 55, 12};
int newLength = array.length;

int[] copiedArray = Arrays.copyOf(array, newLength);