Question

我正在Java中实现一个基于其键排序的MaxHeap。每个键也与一个值相关联。当我尝试运行我的程序时，我得到一个异常：Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [LMaxHeap$Obj;

编辑此行引发异常：o = (Obj[])new Object[n+1];

如何解决我的问题？

这是我的代码：

public class MaxHeap<Key,Value> {

    Obj [] o;
    int N;
    int size;
    private Comparator<Key> comparator;

    public MaxHeap(int n){
        o = (Obj[])new Object[n+1];
        size =0;
        N = n;
    }

    public class Obj{
        Key k;
        Value v;

        public Obj(Key k, Value v){
            this.k = k;
            this.v = v;
        }
    }


void push(Key k, Value v) {
        Obj temp = new Obj(k,v);
        o[++size] = temp;
        swim(size);
    }

Obj pop() {
    Obj del = o[1];

    Obj temp = o[1];
    o[1] = o[size];
    o[size--] = temp;

    sink(1);
    return del;
}

boolean isLess(int i, int j){
    return ((Comparable<Key>) o[i].k).compareTo(o[j].k) < 0;
    }

void swim(int index){
    Obj temp;
    while(index > 1 && isLess(index/2,index)){
            temp = o[index];
            o[index] = o[index/2];
            o[index/2] = temp;

            index = index/2;
        }
    }

void sink(int index){
    int i;
    Obj temp;
    while(2*index <= size){
        i = 2*index;
        if(i < size && isLess(i, i+1))
            i++;
        if(!isLess(index,i))
            break;  
        temp = o[index];
        o[index] = o[i];
        o[i] = temp;

        index = i;
        }
    }

}

Answer 1

查看它将给出行号的异常。看看你要投掷什么。您可以在转换之前使用instanceof运算符进行测试。

使用键，值对实现MaxHeap

1 个答案: