将项添加到数组中的特定位置

function insertItem(array, item, index) {
  array.splice(index, 0, item);
  return array;
}

var array = [1, 2, 3, 4];
var item = 5;
var index = 2;
var newArray = insertItem(array, item, index);
console.log(newArray); // [1, 2, 5, 3, 4]

def insert_item(array, item, index):
  array.insert(index, item)
  return array

array = [1, 2, 3, 4]
item = 5
index = 2
new_array = insert_item(array, item, index)
print(new_array) # [1, 2, 5, 3, 4]

import java.util.Arrays;

public class InsertItem {
  public static void main(String[] args) {
    int[] array = {1, 2, 3, 4};
    int item = 5;
    int index = 2;
    int[] newArray = insertItem(array, item, index);
    System.out.println(Arrays.toString(newArray)); // [1, 2, 5, 3, 4]
  }

  public static int[] insertItem(int[] array, int item, int index) {
    int[] newArray = new int[array.length + 1];
    System.arraycopy(array, 0, newArray, 0, index);
    newArray[index] = item;
    System.arraycopy(array, index, newArray, index + 1, array.length - index);
    return newArray;
  }
}