Question

我有一个HeapInterface和一个带有基于数组的实现的Heap类。我试图制作整数类的堆，但我收到以下错误：

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Comparable;
at HeapArray.<init>(HeapArray.java:16)
at HeapArray.<init>(HeapArray.java:10)
at Test.main(Test.java:5)

我将提供每个类的声明，构造函数和产生错误的测试方法，希望有人可以解释我的错误......

public interface HeapInterface<T extends Comparable<? super T>> {...}

public class HeapArray<T extends Comparable<? super T>> implements HeapInterface<T> {
   private T[] heap;
   private static final int DEFAULT_CAPACITY = 10;
   private int numberOfEntries;

   public HeapArray() {
      this(DEFAULT_CAPACITY);
   }//end default constructor

   public HeapArray(int capacity) {
      numberOfEntries = 0;
      @SuppressWarnings("unchecked")
      T[] tempHeap = (T[]) new Object[capacity];
      heap = tempHeap;
   }//end alternative constructor

   ...
}

public class Test {

   public static void main(String[] args) {
      HeapInterface<Integer> h = new HeapArray<Integer>();

      for(int i = 0; i < 16; i++)
         h.add(i);

      System.out.println(h);
   }
}

有什么想法吗？

Answer 1

你不能将一个Object []强制转换为T []，同时断言T是可比较的，因为一个对象不具有可比性。尝试创建Comparable[]并将其投射到T[]：

  T[] tempHeap = (T[]) new Comparable[capacity];

问题<t extends =“”可比<？=“”super =“”t =“”>＆gt; </t>

1 个答案: