用Java实现几种常用排序算法（先实现一个org.rut.util.algorithm.SortUtil）

先实现org.rut.util.algorithm.SortUtil这个类（以后每个排序都会用到）：

package org.rut.util.algorithm; import org.rut.util.algorithm.support.BubbleSort; import org.rut.util.algorithm.support.HeapSort; import org.rut.util.algorithm.support.ImprovedMergeSort; import org.rut.util.algorithm.support.ImprovedQuickSort; import org.rut.util.algorithm.support.InsertSort; import org.rut.util.algorithm.support.MergeSort; import org.rut.util.algorithm.support.QuickSort; import org.rut.util.algorithm.support.SelectionSort; import org.rut.util.algorithm.support.ShellSort; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class SortUtil { public final static int INSERT = 1; public final static int BUBBLE = 2; public final static int SELECTION = 3; public final static int SHELL = 4; public final static int QUICK = 5; public final static int IMPROVED_QUICK = 6; public final static int MERGE = 7; public final static int IMPROVED_MERGE = 8; public final static int HEAP = 9; public static void sort(int[] data) { sort(data, IMPROVED_QUICK); } private static String[] name={ "insert", "bubble", "selection", "shell", "quick", "improved_quick", "merge", "improved_merge", "heap" }; private static Sort[] impl=new Sort[]{ new InsertSort(), new BubbleSort(), new SelectionSort(), new ShellSort(), new QuickSort(), new ImprovedQuickSort(), new MergeSort(), new ImprovedMergeSort(), new HeapSort() }; public static String toString(int algorithm){ return name[algorithm-1]; } public static void sort(int[] data, int algorithm) { impl[algorithm-1].sort(data); } public static interface Sort { public void sort(int[] data); } public static void swap(int[] data, int i, int j) { int temp = data[i]; data[i] = data[j]; data[j] = temp; } } 

OK,下面开始我们的排序实现；

1. 插入排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class InsertSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int temp; for(int i=1;i<data.length;i++){ for(int j=i;(j>0)&&(data[j]<data[j-1]);j--){ SortUtil.swap(data,j,j-1); } } } } 

2. 冒泡排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class BubbleSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int temp; for(int i=0;i<data.length;i++){ for(int j=data.length-1;j>i;j--){ if(data[j]<data[j-1]){ SortUtil.swap(data,j,j-1); } } } } } 

3.  选择排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class SelectionSort implements SortUtil.Sort { /* * (non-Javadoc) * * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int temp; for (int i = 0; i < data.length; i++) { int lowIndex = i; for (int j = data.length - 1; j > i; j--) { if (data[j] < data[lowIndex]) { lowIndex = j; } } SortUtil.swap(data,i,lowIndex); } } } 

4. Shell排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class ShellSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { for(int i=data.length/2;i>2;i/=2){ for(int j=0;j<i;j++){ insertSort(data,j,i); } } insertSort(data,0,1); } /** * @param data * @param j * @param i */ private void insertSort(int[] data, int start, int inc) { int temp; for(int i=start+inc;i<data.length;i+=inc){ for(int j=i;(j>=inc)&&(data[j]<data[j-inc]);j-=inc){ SortUtil.swap(data,j,j-inc); } } } } 

5. 快速排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class QuickSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { quickSort(data,0,data.length-1); } private void quickSort(int[] data,int i,int j){ int pivotIndex=(i+j)/2; //swap SortUtil.swap(data,pivotIndex,j); int k=partition(data,i-1,j,data[j]); SortUtil.swap(data,k,j); if((k-i)>1) quickSort(data,i,k-1); if((j-k)>1) quickSort(data,k+1,j); } /** * @param data * @param i * @param j * @return */ private int partition(int[] data, int l, int r,int pivot) { do{ while(data[++l]<pivot); while((r!=0)&&data[--r]>pivot); SortUtil.swap(data,l,r); } while(l<r); SortUtil.swap(data,l,r); return l; } } 

6. 改进后的快速排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class ImprovedQuickSort implements SortUtil.Sort { private static int MAX_STACK_SIZE=4096; private static int THRESHOLD=10; /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int[] stack=new int[MAX_STACK_SIZE]; int top=-1; int pivot; int pivotIndex,l,r; stack[++top]=0; stack[++top]=data.length-1; while(top>0){ int j=stack[top--]; int i=stack[top--]; pivotIndex=(i+j)/2; pivot=data[pivotIndex]; SortUtil.swap(data,pivotIndex,j); //partition l=i-1; r=j; do{ while(data[++l]<pivot); while((r!=0)&&(data[--r]>pivot)); SortUtil.swap(data,l,r); } while(l<r); SortUtil.swap(data,l,r); SortUtil.swap(data,l,j); if((l-i)>THRESHOLD){ stack[++top]=i; stack[++top]=l-1; } if((j-l)>THRESHOLD){ stack[++top]=l+1; stack[++top]=j; } } //new InsertSort().sort(data); insertSort(data); } /** * @param data */ private void insertSort(int[] data) { int temp; for(int i=1;i<data.length;i++){ for(int j=i;(j>0)&&(data[j]<data[j-1]);j--){ SortUtil.swap(data,j,j-1); } } } } 

7. 归并排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class MergeSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int[] temp=new int[data.length]; mergeSort(data,temp,0,data.length-1); } private void mergeSort(int[] data,int[] temp,int l,int r){ int mid=(l+r)/2; if(l==r) return ; mergeSort(data,temp,l,mid); mergeSort(data,temp,mid+1,r); for(int i=l;i<=r;i++){ temp[i]=data[i]; } int i1=l; int i2=mid+1; for(int cur=l;cur<=r;cur++){ if(i1==mid+1) data[cur]=temp[i2++]; else if(i2>r) data[cur]=temp[i1++]; else if(temp[i1]<temp[i2]) data[cur]=temp[i1++]; else data[cur]=temp[i2++]; } } }  

8. 改进后的归并排序:

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class ImprovedMergeSort implements SortUtil.Sort { private static final int THRESHOLD = 10; /* * (non-Javadoc) * * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { int[] temp=new int[data.length]; mergeSort(data,temp,0,data.length-1); } private void mergeSort(int[] data, int[] temp, int l, int r) { int i, j, k; int mid = (l + r) / 2; if (l == r) return; if ((mid - l) >= THRESHOLD) mergeSort(data, temp, l, mid); else insertSort(data, l, mid - l + 1); if ((r - mid) > THRESHOLD) mergeSort(data, temp, mid + 1, r); else insertSort(data, mid + 1, r - mid); for (i = l; i <= mid; i++) { temp[i] = data[i]; } for (j = 1; j <= r - mid; j++) { temp[r - j + 1] = data[j + mid]; } int a = temp[l]; int b = temp[r]; for (i = l, j = r, k = l; k <= r; k++) { if (a < b) { data[k] = temp[i++]; a = temp[i]; } else { data[k] = temp[j--]; b = temp[j]; } } } /** * @param data * @param l * @param i */ private void insertSort(int[] data, int start, int len) { for(int i=start+1;i<start+len;i++){ for(int j=i;(j>start) && data[j]<data[j-1];j--){ SortUtil.swap(data,j,j-1); } } } } 

9. 堆排序：

package org.rut.util.algorithm.support; import org.rut.util.algorithm.SortUtil; /** * @author treeroot * @since 2006-2-2 * @version 1.0 */ public class HeapSort implements SortUtil.Sort{ /* (non-Javadoc) * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[]) */ public void sort(int[] data) { MaxHeap h=new MaxHeap(); h.init(data); for(int i=0;i<data.length;i++) h.remove(); System.arraycopy(h.queue,1,data,0,data.length); } private static class MaxHeap{ void init(int[] data){ this.queue=new int[data.length+1]; for(int i=0;i<data.length;i++){ queue[++size]=data[i]; fixUp(size); } } private int size=0; private int[] queue; public int get() { return queue[1]; } public void remove() { SortUtil.swap(queue,1,size--); fixDown(1); } //fixdown private void fixDown(int k) { int j; while ((j = k << 1) <= size) { if (j < size && queue[j]<queue[j+1]) j++; if (queue[k]>queue[j]) //不用交换 break; SortUtil.swap(queue,j,k); k = j; } } private void fixUp(int k) { while (k > 1) { int j = k >> 1; if (queue[j]>queue[k]) break; SortUtil.swap(queue,j,k); k = j; } } } } 

若大家还有好的排序方法，可留言告知在下，谢谢了！