堆的数据结构java

public class MaxHeap {
    private int[] data;
    private int count;
 private int capacity;


 public MaxHeap(int capacity){
 this.capacity=capacity;
 data=new int[capacity+1];
 count=0;
 }
 public void insert(int n)
 {
 data[++count]=n;
 shiftUp(count);
 }

 private void shiftUp(int n) {


 while(n>1&&data[n/2]<data[n])
 {
 swap(data,n/2,n);
 n=n/2;
 }
 }
 public int size(){
 return count;
 }
 public boolean isEmpty(){
 return count==0;
 }
 public int getMax()//复制一个最大值
 {
 assert (count>0);
 return data[1];
 }
 public int extractMax()//直接将最大值取出来了，堆里面没有了
 {
 assert(count-1>0);
 int max=data[1];
 swap(data,count,1);
 count--;
 shiftDown(1);
 return max;
 }

 private void shiftDown(int i) {
 int j=i*2; //找出左节点
 while(j<=count) //如果存在子节点，就要继续往下走，不论是否存在右节点
 {
 if(j+1<=count&&data[j+1]>data[j]) //如果存在右节点，比较左右节点
 {
 if(data[j+1]>data[i])
 {
 swap(data, i, j + 1);
 i = j + 1;
 j = 2 * i;
 }
 else
 break;
 }
 else
 {
 if(data[j]>data[i])
 {
 swap(data,i,j);
 i=j;
 j=2*i;
 }
 else
 break;
 }
 }

 }

 public void swap(int[] arr,int l,int r)
 {
 int temp=arr[l];
 arr[l]=arr[r];
 arr[r]=temp;
 }

 public static void main(String[] args) {
 MaxHeap maxHeap=new MaxHeap(100);
 int N=100;
 int M=100;
 for(int i=1;i<=100;i++)
 {
 maxHeap.insert((int) (Math.random()*M));
 }
 int[] arr=new int[N];
 for(int i=0;i<N;i++)
 {
 arr[i]=maxHeap.extractMax();
 }
 for (int i = 0; i <N ; i++) {
 System.out.println(arr[i]);
 }
 }

}