Java 堆排序 Java实现堆排序(Heapsort)实例代码

public class HeapSort {

    public static void heapSort(DataWraper[] data){
        System.out.println("开始排序");
        int arrayLength=data.length;
        //循环建堆
        for(int i=0;i<arrayLength-1;i++){
            //建堆
            buildMaxHeap(data,arrayLength-1-i);
            //交换堆顶和最后一个元素
            swap(data,0,arrayLength-1-i);
            System.out.println(Arrays.toString(data));
        }
    }

    private static void swap(DataWraper[] data, int i, int j) {
        // TODO Auto-generated method stub
        DataWraper tmp=data[i];
        data[i]=data[j];
        data[j]=tmp;
    }
    //对data数组从0到lastIndex建大顶堆
    private static void buildMaxHeap(DataWraper[] data, int lastIndex) {
        // TODO Auto-generated method stub
        //从lastIndex处节点（最后一个节点）的父节点开始
        for(int i=(lastIndex-1)/2;i>=0;i--){
            //k保存正在判断的节点
            int k=i;
            //如果当前k节点的子节点存在
            while(k*2+1<=lastIndex){
                //k节点的左子节点的索引
                int biggerIndex=2*k+1;
                //如果biggerIndex小于lastIndex，即biggerIndex+1代表的k节点的右子节点存在
                if(biggerIndex<lastIndex){
                    //若果右子节点的值较大
                    if(data[biggerIndex].compareTo(data[biggerIndex+1])<0){
                        //biggerIndex总是记录较大子节点的索引
                        biggerIndex++;
                    }
                }
                //如果k节点的值小于其较大的子节点的值
                if(data[k].compareTo(data[biggerIndex])<0){
                    //交换他们
                    swap(data,k,biggerIndex);
                    //将biggerIndex赋予k，开始while循环的下一次循环，重新保证k节点的值大于其左右子节点的值
                    k=biggerIndex;
                }else{
                    break;
                }
            }
        }
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        DataWraper [] data={
                new DataWraper(21, ""),
                new DataWraper(30, ""),
                new DataWraper(49, ""),
                new DataWraper(30, "*"),
                new DataWraper(16, ""),
                new DataWraper(9, ""),

        };
        System.out.println("排序之前：\n"+Arrays.toString(data));
        heapSort(data);
        System.out.println("排序之后：\n"+Arrays.toString(data));
    }

}