求给定数据中最小的K个数

public class MinHeap {
    /*
     *
     * Top K个问题，求给定数据中最小的K个数
     *
     * 最小堆解决：堆顶元素为堆中最大元素
     *
     *
     *
     */
    private int MAX_DATA = 10;//最小10个数
    private int[] data;//存储数据
    private int len;//当前存储长度，考虑到元素个数可能没有10个，这个时候全部输出
    private MinHeap() {
        data = new int[MAX_DATA];
        len=0;
    }
    private MinHeap(int max) {
        this.MAX_DATA = max;
        data = new int[MAX_DATA];
        len=0;
    }

    public void setRoot(int root) {
        this.data[0] = root;
    }

    public void addData(int da) {
        if (this.len < this.MAX_DATA)
        {
            this.data[this.len] = da;
            len++;
            if(len==this.MAX_DATA)
                this.adjust(0);
        }
        else if(da<this.getRoot())
        {
            this.setRoot(da);
            this.adjust(0);
        }
    }
    private void adjust(int index)
    {
        int left=index*2+1;
        int right=index*2+2;

        if(left<this.len&&right<(this.len)&&data[index]>=data[left]&&data[index]>=data[right])
            return;
        if(left<this.len&&data[index]<data[left])
        {
            data[index]^=data[left];//两个数交换
            data[left]^=data[index];
            data[index]^=data[left];
            this.adjust(left);
        }
        if(right<(this.len)&&data[index]<data[right])
        {
            data[index]^=data[right];
            data[right]^=data[index];
            data[index]^=data[right];
            this.adjust(right);
        }
    }
    private int getRoot()
    {
        return this.data[0];
    }
    public String toString()
    {
        for(int i=0;i<this.len;i++)
            System.out.print(data[i]+"/");
        return null;
    }

    public static void main(String args[])
    {
        MinHeap min=new MinHeap();
        for(int i=200;i>0;i--)
        {
            min.addData(i);
            min.toString();
            System.out.print("\n");
        }
    }
}