选择排序算法的JAVA实现

public class SelectionSortArray {
    /*
     * Task:将数组中前n个对象按升序排列
     * @param a Comparable 对象的数组
     * @param n 大于0的整数，表示数组的长度
     */
    public static <T extends Comparable<? super T>> void selectionSort(T[] a, int n){
        for(int index = 0; index < n-1; index++){
            int indexOfNextSmallest = getIndexOfSmallest(a, index, n-1);
            swap(a, index, indexOfNextSmallest);
        }
    }
    
    //返回索引first 至 索引last 之间的最小值的索引
    private static <T extends Comparable<? super T>> int getIndexOfSmallest(T[] a, int first, int last){
        T min = a[first];
        int indexOfMin = first;
        for(int index = first + 1; index <= last; index++){
            if(a[index].compareTo(min) < 0){
                min = a[index];
                indexOfMin = index;
            }//end if
        }
        return indexOfMin;
    }
    
    //交换数组元素不涉及compareTo方法，因而使用Object作为元素类型
    private static void swap(Object[] a, int i, int j){
        Object temp = a[i];//交换的并不是引用，而是具体的元素的值
        a[i] = a[j];
        a[j] = temp;
    }
    
    //选择排序的递归方法
    public static <T extends Comparable<? super T>> void selectionSort_Recursive(T[] a, int n){
        selectionSort(a, 0, n - 1);
    } 
    
    private static <T extends Comparable<? super T>> void selectionSort(T[] a, int first, int last){
        if(first < last)
        {
            int indexOfNextSmallest = getIndexOfSmallest(a, first, last);
            swap(a, first, indexOfNextSmallest);
            selectionSort(a, first + 1, last);
        }
    }
}