用Java泛型實現快速排序

package ch10;public class QuickSort {/** * successfully-快速排序 * 使用了泛型-自然排序 * @param <T> * @param t */public static <T extends Comparable> void quikSort(T[] t){recursiveSort(t, 0, t.length-1);}/** * 快速排序-遞迴調用 * @param <T> * @param t * @param low * @param high */private static <T extends Comparable> void recursiveSort(T[] t, int low, int high){if(t == null || low >= high) return;int pivotLoc = partition(t, low, high);//先對長度較短的子序列進行快速排序，以使棧的最大深度在最壞情況下降為O(logn)if(pivotLoc-low > high-pivotLoc){recursiveSort(t, pivotLoc+1, high);recursiveSort(t, low, pivotLoc-1);}else{recursiveSort(t, low, pivotLoc-1);recursiveSort(t, pivotLoc+1, high);}}/** * 快速排序-一次劃分 * @param <T> * @param t * @param low * @param high * @return */private static <T extends Comparable> int partition(T[] t, int low, int high){selectPivotKey(t, low, high);//System.out.println("low---"+t[low]);T pivotKey = t[low];while(low < high){while(t[high].compareTo(pivotKey)>=0 && low<high){high--;}t[low] = t[high];while(t[low].compareTo(pivotKey)<=0 && low<high){low++;}t[high] = t[low];}t[low] = pivotKey;return low;}/** * 快速排序-三者取中來設定pivotKey * @param <T> * @param t * @param low * @param high * @return */private static <T extends Comparable> boolean selectPivotKey(T[] t, int low, int high) {if(t==null || low < 0 || high > t.length){throw new IllegalArgumentException("參數傳遞不正確");}T min = t[low];T mid = t[(low+high)/2];T max = t[high];if(min.compareTo(mid) > 0){T temp = min;min = mid;mid = temp;}if(max.compareTo(min) < 0) mid = min;else if(max.compareTo(mid) < 0) mid = max;if(mid.compareTo(t[low]) == 0) return true;else if(mid.compareTo(t[(low+high)/2]) == 0){return swap(t, low, (low+high)/2);}else{return swap(t, low, high);}}/** * 交換數組中的元素 * @param <T> * @param t * @param i * @param j */private static <T> boolean swap(T[] t, int i, int j){if(i<0 || i>=t.length || j<0 || j>=t.length) return false;if(t == null) return true;T temp = t[i];t[i] = t[j];t[j] = temp;return true;}public static void main(String[] args) {Integer[] arr = new Integer[]{1,2,5,4,5,6,7,8,9};QuickSort.<Integer>quikSort(arr);for(int i : arr){System.out.println(i);}}}