java五种排序算法汇总工具类

这个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。

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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 ; } 更多最佳实践技术文章