main中未定义的方法，使用双端队列

Question

I am working with a deque

MyDeque theQueue = new MyDeque(queElm);

in main MyDequeApp that calls a method

theQueue = insertFront(10);

the method is in a class called MyDeque

public void insertFront(Item x)
{
    if(front==maxSize)
        front=0;
    queArray[front++]=x;
    nItems++;
}

I am getting an error in main when calling insertFront saying

The method insertFront() is undefined for type MyDequeApp

I don't understand this error as I believe the method is defined in MyDeque , if someone could shed some light it would help me out.

Answer 1

You are passing int value, but it requires Item object.

 public void insertFront(Item x)

If you look at method signature, this method with name insertFront accepts values of type Item

Answer 2

You're calling the method incorrectly. insertFront is a method on the MyDeque class. So to call it you need to call it from your instance of MyDeque . The error is saying you're calling it from MyDequeApp , not MyDeque .

Replace:

theQueue = insertFront(10);

With:

theQueue.insertFront(10);

As Nambari mentioned, you're also passing the wrong kind of value. It's expecting an Item but you're passing an int . Instead, create an instance of Item and pass that to the method.

I'd personally also change the name of the variable since it's a deque, not a queue.