JAVAは小根の並び替えを実現

import java.util.Arrays;
public class solution {
     public static void main(String []args){
       int a[]={5,3,6,4,1,11,9,21,4,5,-5};
       heapSort(a);
       System.out.println(Arrays.toString(a));
    }


    public static void heapAdjust(int arr[],int start,int end){
         int tem=arr[start];
         for (int i=2*start+1;i<=end;i*=2){
             if (iarr[i+1])
                 i++;
             if (tem<=arr[i])
                 break;
             arr[start]=arr[i];
             arr[i]=tem;
             start=i;
         }
    }
    public static void heapSort(int []arr){
         if (arr==null||arr.length==0)
             return;
         for(int i=arr.length/2;i>=0;i--)
             heapAdjust(arr,i,arr.length-1);
         System.out.println(arr[0]);

         for (int i=arr.length-1 ;i>=0;i--){
             swap(arr,0,i);  //                                    
             heapAdjust(arr,0,i-1);
         }
    }
    public static void swap(int arr[],int i,int j){
         int t=arr[i];
         arr[i]=arr[j];
         arr[j]=t;
    }