从另一个类的构造函数获取价值

Question

I am sure this is a very easy question for many, but I am struggling with it. I am trying to get a value from the following constructor and place it in a vector.

Each time I add the object to the vector though, the value that is placed inside the vector is null. How can I get the number to be the value that is placed into the vector?

The CInteger class:

public class CInteger  
{
    private int i;
    CInteger(int ii)
    {
        i = ii;
    }
}

And in my A1 class, the constructor and my attempt at getting the value:

    Object enqueue(Object o) 
    {
        CInteger ci = new CInteger(88);
        Object d = ??
        add(tailIndex, d);// add the item at the tail
    }

Thank you all for any insight and help, I am still learning.

EDIT: SOLVED

CInteger class:

public class CInteger implements Cloneable // Cloneable Integer 
{
    int i;
     CInteger(int ii)
    {
        this.i = ii;
    }

public int getValue()
    {
        return i;
    }

}

Both enqueue methods:

public void enqueue(CInteger i)  // enqueue() for the CInteger
{
    add(tailIndex, new Integer(i.getValue())); get int value and cast to Int object
}
public void enqueue(Date d)  // enqueue() for the Date object
{
    add(tailIndex, d);
}

Thank you very much everyone. :D

Answer 1

You can simply overload the enqueue class to take both Dates and Integers. In either case, it sounds like you need a method getValue() in CInteger that lets you access the int value.

public class CInteger
{
    //constructors, data

    public void getValue()
    {
        return i;
    }
}

and then you can have two enqueue() methods in your other class:

public void enqueue(Date d)
{
    add(tailIndex, d);
}

public void enqueue(CInteger i)
{
    add(tailIndex, new Integer(i.getValue()); //access the int value and cast to Integer object
}

And Java will know which one you are calling automatically based on the parameters.

Answer 2

It is not entirely clear what you are actually trying to do, but I think that this will suffice:

Object enqueue() {
    CInteger ci = new CInteger(88);
    add(tailIndex, ci);// add the item at the tail
    return ci;  // this will automatically upcast ci as an Object
}

Answer 3

Try this.

public class CInteger {
    private int i;

    CInteger(int ii) {
       this.i = ii;
    }
}

Using the this Keyword

Answer 4

Wouldn't it just be:

void main(string[] args)
{
    CInteger ci = new CInteger(88);

    encqueue(ci.i);
}

Object enqueue(Object o) 
{
    add(tailIndex, o);
}

Or am I missing something?

Answer 5

First of all, Constructors never return any value. You have to access the value through its objects or you have to use getter methods.

In your case, " private int i; " can not be accessed directly. So try make either it as public or have some getter method.

So try it:

    CInteger ci = new CInteger(88);
    Object d = ci.i; // if i is public member
    add(tailIndex, d);

or

    ...
    private int i;
    ...
    public int getI() {
        return  this.i;
    }
    ...
    CInteger ci = new CInteger(88);
    Object d = ci.getI(); 
    add(tailIndex, d);