一点点最简单的java排序算法

public class NumberSort2 {

   public static void main(String[] args){

   

   int[] b ={2, 4, 6, 7, 3, 5, 1, 9, 8};

   print(b);

   selectionSort(b);

   //selectionSort2(b);

   //bubbleSort(b);

   print(b);

    }

   

//冒泡法是一格一格的走，就是说每次只和相邻的格子交换。相当于每次外层循环把最大的数，放到当前循环能接触位置的最下面

   private static void bubbleSort (int[] a){

       int len = a.length;

       int temp;

       for(int i=len-1; i>=0; i--){

           for(int j=0;j < i;j++){

                if (a[j]>a[i]){

                    temp = a[i];

                    a[i] = a[j];

                    a[j] = temp;

                }            

           }

       }

    }

   

         //最基本的排序算法，每次外层循环有可能有很多次交换

   private static void selectionSort(int[] a){

       int temp = 0;

       for(int i = 0; i <a.length;i++){

           for (int j = i+1; j<a.length; j++){

                if (a[j] < a[i]){

                temp = a[i];

                a[i] = a[j];

                a[j] = temp;

                }

           }

       }

    }

   

 

 

 

         //在以上算法上改进，先比较，找到本次外层循环的最小数字，再进行交换

   private static void selectionSort2(int[] a){

       int k,temp = 0;

       for(int i = 0; i <a.length;i++){

           k = i;

           for (int j = k+1; j<a.length; j++){

                if (a[j] < a[k]){

                    k = j ;

                }

           }

           if (k != i){

                temp = a[i];

                a[i] = a[k];

                a[k] = temp;

           }

        }

    }

   

   private static void print(int[] a){

       for (int i =0; i<a.length; i++){

           System.out.print(a[i] + " ");

       }

       System.out.println();

    }

}