找出某个数组范围内的值/元素

Question

I would like to find out if there is a java function that can check the values from index 0-5? For example. Without using a loop Is there a function that identifies the elements in sub Array1 [0-5] as { 1,2,3,4,5} int Array1[]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 } . Thanks for your help.

Answer 1

You can use Arrays.copyOfRange(arr, start, end) this will return you an array containing the specified range from the original arr array.

start is inclusive, end is exclusive

eg for your case

int[] arr = new int[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
int[] subArr = Arrays.copyOfRange(arr, 0, 5);

Answer 2

I would not use arrays. Lists are easier to use. Especially if you want to work with sub arrays since there is no copying using lists. The sublist is a constrained view of the original list (it's the same list with modified start and ending indices).

List<Integer> intList = List.of(1,2,3,4,5,6,7);
List<Integer> intSublist = list.subList(0,5);

System.out.println(intSublist.equals(List.of(1,2,3,4,5)));

prints

true

Answer 3

There are more then one way to do this but this could be one of it:

int[] arr = new int[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};

//starts everytime by element 0
int[] subArr = Arrays.copyOf(arr, 5);

or this

int[] arr = new int[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
int[] subArr = Arrays.copyOfRange(arr, 0,5);

but end the end they use System.arraycopy(...) so you can use this directly:

int[] arr = new int[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
int[] subArr = new int[5];

//starts at the specified index here 0
System.arraycopy(arr, 0, subArr, 0, subArr.length);