Java编写程序：用泛型写​数组元素倒置，数组元素分拆，数组元素合并

在Java中，可以利用泛型（Generics）来编写一些通用的函数，例如倒置数组、分拆数组和合并数组。这里简单提供一个示例：

import java.util.Arrays;

public class ArrayUtils<T> {
    // 数组元素倒置
    public static T[] reverseArray(T[] arr) {
        int start = 0;
        int end = arr.length - 1;
        while (start < end) {
            T temp = arr[start];
            arr[start] = arr[end];
            arr[end] = temp;
            start++;
            end--;
        }
        return arr;
    }

    // 数组元素分拆成两部分
    public static T[][] splitArray(T[] arr, int partitionIndex) {
        if (partitionIndex > arr.length) {
            throw new IllegalArgumentException("Partition index is out of bounds");
        }
        T[] firstPart = Arrays.copyOfRange(arr, 0, partitionIndex);
        T[] secondPart = Arrays.copyOfRange(arr, partitionIndex, arr.length);
        return new T[][] {firstPart, secondPart};
    }

    // 合并两个已排序的数组
    public static <T extends Comparable<T>> T[] mergeSortedArrays(T[] array1, T[] array2) {
        T[] mergedArray = Arrays.copyOf(array1, array1.length + array2.length);
        mergeSort(mergedArray, 0, array1.length - 1);
        mergeSort(mergedArray, array1.length, mergedArray.length - 1);
        merge(mergedArray, array1.length, array2.length - 1);
        return mergedArray;
    }

    private static void merge(T[] arr, int left, int right) {
        int i = left, j = right, k = left;

        while (i <= j) {
            if (arr[i].compareTo(arr[j]) <= 0) {
                arr[k++] = arr[i++];
            } else {
                arr[k++] = arr[j--];
            }
        }
    }

    private static void mergeSort(T[] arr, int low, int high) {
        if (low < high) {
            int mid = low + (high - low) / 2;
            mergeSort(arr, low, mid);
            mergeSort(arr, mid + 1, high);
            merge(arr, low, mid, high);
        }
    }
}

// 使用示例：
Integer[] numbers = {1, 3, 5, 7, 9};
Integer[] reversedNumbers = ArrayUtils.reverseArray(numbers); // [9, 7, 5, 3, 1]
Integer[][] splitNumbers = ArrayUtils.splitArray(numbers, 3); // [[1, 3, 5], [7, 9]]
Integer[] mergedNumbers = ArrayUtils.mergeSortedArrays(numbers, new Integer[]{4, 6, 8}); // [1, 3, 4, 5, 6, 7, 8, 9]