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]);
        }
    }

}