5种java排序算法汇总工具类

工具类简单明了地总结了java的快速排序，希尔排序，插入排序，堆排序，归并排序五种排序算法，代码中并没有对这几种排序算法的一个说明，关于思想部分希望在自行查阅相关说明，这里只是对这几种算法进行一个概括，以供大家使用。

public class Sort { public static <AnyType extends Comparable<? super AnyType>> void insertionSort(AnyType[] a) {  insertionSort(a, 0, a.length - 1); }  private static <AnyType extends Comparable<? super AnyType>> void insertionSort(AnyType[] a, int left, int right) {  int j; // 记录第一个比tmp小的元素的后边一位的位置   for (int p = left; p <= right; p++) {   AnyType tmp = a[p];   for (j = p; j > left && tmp.compareTo(a[j - 1]) < 0; j--) {    a[j] = a[j - 1];   }   a[j] = tmp;  } }  public static <AnyType extends Comparable<? super AnyType>> void shellSort(AnyType[] arr) {  int j;   for (int gap = arr.length / 2; gap > 0; gap /= 2) {   for (int i = gap; i < arr.length; i++) {    AnyType tmp = arr[i];    for (j = i; j >= gap && tmp.compareTo(arr[j - gap]) < 0; j -= gap) {     arr[j] = arr[j - gap];    }    arr[j] = tmp;   }  } }  private static int leftChild(int i) {  return i * 2 + 1; }  private static <AnyType extends Comparable<? super AnyType>> void perculateDown(AnyType[] arr, int i, int size) {  AnyType tmp = arr[i];   for (int child; (child = leftChild(i)) < size; i = child) {   if (child != size - 1 && arr[child].compareTo(arr[child + 1]) < 0) {    child++;   }   if (tmp.compareTo(arr[child]) < 0) {    arr[i] = arr[child];   } else {    break;   }  }  arr[i] = tmp; }  public static <AnyType extends Comparable<? super AnyType>> void heapSort(AnyType[] arr) {  for (int i = arr.length / 2; i >= 0; i--) {   perculateDown(arr, i, arr.length);  }  for (int i = arr.length - 1; i >= 0; i--) {   swapReferences(arr, 0, i);   perculateDown(arr, 0, i);  } }  private static <AnyType extends Comparable<? super AnyType>> void swapReferences(AnyType[] arr, int i, int j) {  AnyType tmp = arr[i];  arr[i] = arr[j];  arr[j] = tmp; }  public static <AnyType extends Comparable<? super AnyType>> void mergeSort(AnyType[] arr) {  AnyType[] tmp = ((AnyType[]) new Comparable[arr.length]);  mergeSort(arr, 0, arr.length - 1, tmp); }  private static <AnyType extends Comparable<? super AnyType>> void mergeSort(AnyType[] arr, int start, int end, AnyType[] tmp) {  if (start < end) {   int mid = (start + end) >> 1;   mergeSort(arr, start, mid, tmp);   mergeSort(arr, mid + 1, end, tmp);   merge(arr, start, mid, end, tmp);  } }  private static <AnyType extends Comparable<? super AnyType>> void merge(AnyType[] arr, int start, int mid, int end, AnyType[] tmp) {  int i = start, j = mid + 1, k = start;  while (i <= mid && j <= end) {   if (arr[i].compareTo(arr[j]) < 0) {    tmp[k++] = arr[i++];   } else {    tmp[k++] = arr[j++];   }  }   while (i <= mid) {   tmp[k++] = arr[i++];  }   while (j <= end) {   tmp[k++] = arr[j++];  }   for (int m = start; m <= end; m++) {   arr[m] = tmp[m];  } }  public static <AnyType extends Comparable<? super AnyType>> void quickSort(AnyType[] arr) {  quickSort(arr, 0, arr.length - 1); }  private static <AnyType extends Comparable<? super AnyType>> void quickSort(AnyType[] arr, int left, int right) {  if (left + LENGTH_DIFF <= right) {    AnyType pivot = medium(arr, left, right);    int i = left, j = right;   while (true) {    while (arr[++i].compareTo(pivot) < 0);    while (arr[--j].compareTo(pivot) > 0);     if (i < j) {     swapReferences(arr, i, j);    } else {     break;    }   }    swapReferences(arr, i, right);   quickSort(arr, left, i - 1);   quickSort(arr, i + 1, right);  } else {   insertionSort(arr, left, right);  } }  private static <AnyType extends Comparable<? super AnyType>> AnyType medium(AnyType[] arr, int left,   int right) {  int center = (left + right) / 2;  if (arr[center].compareTo(arr[left]) < 0) {   swapReferences(arr, center, left);  }  if (arr[left].compareTo(arr[right]) > 0) {   swapReferences(arr, left, right);  }  if (arr[center].compareTo(arr[right]) < 0) {   swapReferences(arr, center, right);  }     return arr[right]; }  private final static int LENGTH_DIFF = 20;}

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