几种常见排序算法的Java代码实现

首先通过下面一张图了解排序算法的分类：

下面是八种排序算法的Java代码实现：

一.插入排序

简单插入排序

 public class InsertSort {


     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
        int a[]={12,32,4,11,54,33,75,44,8,10};
        insertSort(a);
        for(int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }
     }
     public static void insertSort(int[] a){
         int temp = 0;
         for(int i=1;i<a.length;i++){
             temp = a[i];
             int j;
             for(j=i-1;j>=0;j--){
                 if(temp<a[j]){
                     a[j+1] = a[j];
                     //a[j] =temp;
                 }else{
                     break;
                 }

             }
             a[j+1] =temp;
         }
     }


 }

二分插入排序

 public class ErfenSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int a[]={12,32,4,11,54,33,75,44,8,10};
            erfenSort(a);
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
     public static void erfenSort(int[] a){
         int temp=0;

         for(int i=1;i<a.length;i++){
             temp = a[i];
             int left=0;
             int right = i-1;
             int mid = 0;
             while(left<=right){
                 mid = (left+right)/2;
                 if(a[mid]>temp){
                     right = mid-1;
                 }else{
                     left = mid+1;
                 }
             }
             for(int j=i-1;j>=left;j--){
                 a[j+1] = a[j];
             }
             if(left!=i){
             a[left] = temp;
             }
         }
     }
 }

希尔排序

 public class ShellSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int a[]={12,32,4,11,54,33,75,44,8,10};
            shellSort(a);
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
    public static void shellSort(int[] a){
        int d = a.length;
        int temp = 0;
        while(d!=1){
            d = d/2;
            for(int x=0;x<d;x++){
                for(int i=x+d;i<a.length;i+=d){
                    temp = a[i];
                    int j;
                    for(j=i-d;j>=0;j-=d){
                        if(temp<a[j]){
                            a[j+d] = a[j];
                            //a[j] = temp;
                        }else{
                            break;
                        }
                    }
                    a[j+d] = temp;
                }
            }
        }
    }
 }

二.选择排序

简单选择排序

 public class SelectSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int a[]={12,32,4,11,54,33,75,44,8,10};
            selectSort(a);
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
     public static void selectSort(int[] a){
         int temp = 0;
         for(int i=0;i<a.length;i++){
             int p = i;
             temp = a[i];
             int j;
             for(j=i+1;j<a.length;j++){
                 if(temp>a[j]){
                     temp = a[j];
                     p = j;
                 }

             }
             a[p] = a[i];
             a[i] = temp;
         }
     }

 }

堆排序

 public class HeapSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int a[]={12,32,4,11,54,33,75,44,8,10};
            heapSort(a);
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
    private static void swap(int[] a,int i,int j){
        int temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }
    public static void heapSort(int[] a){
        for(int i=0;i<a.length;i++){
            buildMaxHeap(a,a.length-1-i);
            swap(a,0,a.length-1-i);
        }
    }
    private static void buildMaxHeap(int[]a,int lastIndex){
        for(int i=(lastIndex-1)/2;i>=0;i--){
            int k=i;
            while(2*k+1<=lastIndex){
                int biggerIndex = 2*k+1;
                if(biggerIndex<lastIndex){
                    if(a[biggerIndex]<a[biggerIndex+1]){
                        biggerIndex++;
                    }
                }
                if(a[k]<a[biggerIndex]){
                    swap(a,k,biggerIndex);
                    k = biggerIndex;
                }else{
                    break;
                }
            }
        }
    }
 }

三.交换排序

冒泡排序

 public class BubbleSort {
    public static void main(String[] args){
        int a[]={12,32,4,11,54,33,75,44,8,10};
        bubbleSort(a);
        for(int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }
    }
    public static void bubbleSort(int[] a){
        for(int i=0;i<a.length-1;i++){
            for(int j=0;j<a.length-1-i;j++){
                if(a[j]>a[j+1]){
                    int temp = a[j];
                    a[j] = a[j+1];
                    a[j+1] = temp;
                }

            }
        }
    }
 }

快速排序

 public class QuickSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         int a[]={12,32,4,11,54,33,75,44,8,10};
         if(a.length>0){
           quickSort(a,0,a.length-1);
         }
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
    public static int getMiddle(int[] a,int low,int high){
        int mid = a[low];
        while(low<high){
            //System.out.println(low+" "+high);
        while(low<high&&mid<=a[high]){

            high--;
        }
        a[low] = a[high];
        while(low<high&&mid>=a[low]){

            low++;

        }
        a[high] = a[low];
        }
        a[low] = mid;
        return low;

    }
    public static void quickSort(int[] a,int low,int high){
        if(low<high){
            int middle = getMiddle(a,low,high);
            quickSort(a,low,middle-1);
            quickSort(a,middle+1,high);
        }
    }
 }

四.归并排序

 public class MergingSort {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
           int a[]={12,32,4,11,54,33,75,44,8,10};
            mergingSort(a,0,a.length-1);
            for(int i=0;i<a.length;i++){
                System.out.print(a[i]+" ");
            }
     }
     public static void mergingSort(int[] a,int left,int right){
         if(left<right){
             int center = (left+right)/2;
             mergingSort(a,left,center);
             mergingSort(a,center+1,right);
             meging(a,left,center,right);
         }
     }
     public static void meging(int[] a,int left,int center,int right){
         int[] tmpArr = new int[a.length];
         int mid = center+1;
         int s = left;
         int temp = left;
         while(left<=center&&mid<=right){
             if(a[left]<=a[mid]){
                 tmpArr[temp++] = a[left++];
             }else{
                 tmpArr[temp++] = a[mid++];
             }
         }
         while(mid<=right){
             tmpArr[temp++] = a[mid++];
         }
         while(left<=center){
             tmpArr[temp++] = a[left++];
         }

         while(s<=right){
             a[s] = tmpArr[s++];
         }
     }
 }

五.基数排序

import java.util.ArrayList;  
import java.util.List;  
  
  
public class RadixSort {  

    public static void main(String[] args) {  
        // TODO Auto-generated method stub  
        int a[]={12,32,4,11,54,33,75,44,8,10};  
           radixSort(a);  
           for(int i=0;i<a.length;i++){  
               System.out.print(a[i]+" ");  
           }  
    }  
      
    public static void radixSort(int[] a){  
        int max = a[0];  
        for(int i=0;i<a.length;i++){  
            if(a[i]>max){  
                max = a[i];  
            }  
        }  
        int time = 0;  
        while(max>0){  
            max = max/10;  
            time++;  
        }  
        List<ArrayList> queue = new ArrayList<ArrayList>();  
        for(int i=0;i<10;i++){  
            ArrayList<Integer> queue1 = new ArrayList<Integer>();  
            queue.add(queue1);  
        }  
        for(int i=0;i<time;i++){  
            for(int j=0;j<a.length;j++){  
                int x = a[j]%(int)Math.pow(10, i+1)/(int)Math.pow(10, i);  
                ArrayList<Integer> queue2 = queue.get(x);  
                queue2.add(a[j]);  
                queue.set(x, queue2);  
            }  
            int count = 0;  
            for(int k=0;k<10;k++){  
                while(queue.get(k).size()>0){  
                 ArrayList<Integer> queue3 = queue.get(k);  
                    a[count++] = queue3.get(0);  
                    queue3.remove(0);  
                }  
            }  
        }  
    }  
  
}  

对于求职的应届生小伙伴们，必须熟记以上八种排序（当然重要是理解），面试的时候面试官可能会让你写一个你最拿手的排序算法（千万别写冒泡，丢不起那人！！！），本人建议，快排和堆排序选一个写，逼格瞬间提高，或者两个排序全都写，边写便介绍两种排序的优缺点和适用场景，绝对能让面试官刮目相看！！！！

面试的时候可能还会问及几种排序的时间复杂度和空间复杂度，再次不再多做介绍，网上大把大神写的资料等着你，本文只是讲八种排序算法的Java代码实现，方便初学的小伙伴编程的时候做个参考，以上代码都是本人亲自实现过的，可放心参考！！！