C ++模板和多态性？

Question

I am trying to make the java Queue interface in C++. I cannot get it to compile correctly when inheriting from it.

This is QueueInterface.h

#ifndef QUEUEINTERFACE_H_
#define QUEUEINTERFACE_H_
/**
 * Java like interface
 */
template<class E>
class QueueInterface {
public:
    virtual bool add(E e);
    virtual E element();
    virtual bool offer(E e);
    virtual E peek();
    virtual E poll();
    virtual E remove();
    virtual int size();
    virtual bool isEmpty();
    virtual ~QueueInterface();
};

#endif /* QUEUEINTERFACE_H_ */

This is LinkedQueue.h

#ifndef QUEUE_H_
#define QUEUE_H_
#include "QueueInterface.h"
#include "LinkedList.h"
template<class T>
class LinkedQueue: public QueueInterface<T> {
private:
    LinkedList<T> linkedList;
public:
//DOES NOT COMPILEE
//  virtual bool QueueInterface<T>::add(T t) {
//      return false;
//  }
//  virtual T QueueInterface<T>::element() {
//      T t;
//      return T;
//  }
//  virtual bool QueueInterface::offer(T e) {
//      return false;
//  }
//  virtual T QueueInterface::peek() {
//      T t;
//      return t;
//  }
//  virtual T QueueInterface::poll() {
//      T t;
//      return t;
//  }
//  virtual T QueueInterface::remove() {
//      T t;
//      return t;
//  }
//  virtual int QueueInterface::size() {
//      return -1;
//  }
//  virtual bool QueueInterface::isEmpty() {
//      return false;
//  }
//  virtual QueueInterface::~QueueInterface() {
//  }

};

#endif /* QUEUE_H_ */

How do I use templates and polymorphism to emulate the Queue interface?

Edit:Things I had to change

Interface: //=0 added to functions

   #ifndef QUEUEINTERFACE_H_
    #define QUEUEINTERFACE_H_
    /**
     * Java like interface
     */
    template<class E>
class QueueInterface {
public:
    QueueInterface() {

    }
    virtual bool add(E e)=0;
    virtual E element()=0;
    virtual bool offer(E e)=0;
    virtual E peek()=0;
    virtual E poll()=0;
    virtual E remove()=0;
    virtual int size()=0;
    virtual bool isEmpty()=0;
    virtual ~QueueInterface() {
    }
    ;
};
#endif /* QUEUEINTERFACE_H_ */

LinkedQueue Implementation (not working was just trying to get inheritance to work):

#ifndef QUEUE_H_
#define QUEUE_H_
#include "QueueInterface.h"
#include "LinkedList.h"
template<class T>
class LinkedQueue: public QueueInterface<T> {
private:
    LinkedList<T> linkedList;
public:
     LinkedQueue() {

    }
    virtual bool add(T t) {
        std::cout << "entering add";
        return false;
    }
    virtual T element() {
        T t;
        return t;
    }
    virtual bool offer(T e) {
        return false;
    }
    virtual T peek() {
        T t;
        return t;
    }
    virtual T poll() {
        T t;
        return t;
    }
    virtual T remove() {
        T t;
        return t;
    }
    virtual int size() {
        return -1;
    }
    virtual bool isEmpty() {
        return false;
    }
    virtual ~LinkedQueue() {

    }

};

#endif /* QUEUE_H_ */

If you are transitioning from java to c++ remember that when printing a boolean yields 0 or 1 in c++ compared to true or false in java.

Answer 1

You should implement the operations defined in your queue interface using your LinkedList member:

#ifndef QUEUE_H_
#define QUEUE_H_
#include "QueueInterface.h"
#include "LinkedList.h"

template<class T>
class LinkedQueue: public QueueInterface<T> {
private:
    LinkedList<T> linkedList;
public:

    virtual ~LinkedQueue() {
    }


    virtual bool add(T t) {
        linkedList.push_back(t);
    }
    virtual T element() {
        return linkedList.front();
    }
    virtual size() {
        return linkedList.size();
    }
    virtual isEmpty() {
        return linkedList.empty();
    }
// etc...
// you may need to do some blocking operations
// for some of the members like poll

};

Obviously I don't have the interface for LinkedList, so the list member function calls are based on std::list