java中的泛型二进制搜索树

Question

我想实现泛型类型二叉搜索树.声明如下:

public BTNode<T> {}

public class BinaryTree<T extends Comparable<T>> {}

public class BinarySearchTree <T extends Comparable<T>> extends BinaryTree<T> {}

现在我编写了一个名为Entry的类,并希望将该类的实例存储在BinarySearchTree中.

public class Entry implements Comparable{
private String firstName, lastName, address, phoneNumber;

public Entry(String fName, String lName, String address, String phoneNum) {
    this.firstName = fName;
    this.lastName = lName;
    this.address = address;
    this.phoneNumber = phoneNum;
}

public int compareTo(Object arg0) {
    // TODO Auto-generated method stub
    return 0;
}
}

但是当我声明时BinarySearchTree<Entry> bst,总会出现编译错误:

"绑定不匹配:类型Entry不是BinarySearchTree类型的有界参数的有效替代"

我仍然是Java中泛型类型的新手.任何人都可以帮我解决问题吗？谢谢

Answer 1

您的Entry类需要实现Comparable<Entry>而不是raw Comparable,因为raw Comparable不匹配Comparable<T>.

public class Entry implements Comparable<Entry> { ... }

Answer 2

使您的Entry类实现Comparable<Entry>,使其符合BinaryTree的合约.

合同说"所有类型T扩展(或实现)类型Comparable <T>".你用"Entry"替换"T",你会发现这是必需的:Entry extends Comparable<Entry>