java中的接口,类和构造函数

Question

这是关于接口和类的困扰我的东西.

我正在尝试通过名为IPAddressString的类对名为IPAddress的接口进行实现.Ipadress包含四个部分.

我正在编写一个名为mask的方法,该方法使用给定的掩码屏蔽当前地址.屏蔽操作是对地址的所有四个部分的按位'和'操作.你通过我写的名为getOc​​tet的方法获得了所有这四个部分.(你可以在下面看到).

好的,所以我需要屏蔽我的this.IpAdress用它我用新的通用IPAddress编写了我的类.

在写掩码时,我遇到了问题.我计算了4个整数,我想要返回一个新的IPAddress类型.为了做到这一点,我需要使用我的constructer返回IPAddressString类型,而且我不能将IPAddressString转换为IPAddress.

我迷路了.我该怎么办？为什么我的结构不适合这个？IPAddressString不是IPAddress的子类型吗？

这是使代码更简单的代码:

这是界面:

public interface IPAddress {

    /**
     * Returns a string representation of the IP address, e.g. "192.168.0.1"
     */
    public String toString();

    /**
     * Compares this IPAddress to the specified object
     * 
     * @param other
     *            the IPAddress to compare this string against
     * @return <code>true</code> if both IPAddress objects represent the same IP
     *         address, <code>false</code> otherwise.
     */
    public boolean equals(IPAddress other);

    /**
     * Returns one of the four parts of the IP address. The parts are indexed
     * from left to right. For example, in the IP address 192.168.0.1 part 0 is
     * 192, part 1 is 168, part 2 is 0 and part 3 is 1.
     * 
     * @param index
     *            The index of the IP address part (0, 1, 2 or 3)
     * @return The value of the specified part.
     */
    public int getOctet(int index);

    /**
     * Returns whether this address is a private network address. There are
     * three ranges of addresses reserved for 'private networks' 10.0.0.0 -
     * 10.255.255.255, 172.16.0.0 - 172.31.255.255 and 192.168.0.0 -
     * 192.168.255.255
     * 
     * @return <code>true</code> if this address is in one of the private
     *         network address ranges, <code>false</code> otherwise.
     * @see <a href="http://en.wikipedia.org/wiki/IPv4#Private_networks">Private Networks</a>
     */
    public boolean isPrivateNetwork();

    /**
     * Mask the current address with the given one. The masking operation is a
     * bitwise 'and' operation on all four parts of the address.
     * 
     * @param mask
     *            the IP address with which to mask
     * @return A new IP address representing the result of the mask operation.
     *         The current address is not modified.
     */
    public IPAddress mask(IPAddress mask);
}

这是我的班级:

public class IPAddressString {

    private String IpAdress;

    public IPAddressString(int num1, int num2, int num3, int num4) {
        this.IpAdress = num1 + "." + num2 + "." + num3 + "." + num4;

    }


    public String toString() {
        return this.IpAdress;

    }

    public boolean equals(IPAddress other) {
        return ((other.toString()).equals(IpAdress));
    }

    public int getOctet(int index) {

        StringBuffer buf = new StringBuffer();
        int point = index;
        int countPoints = 0;

        for (int i = 0; i <= IpAdress.length() - 1; i++) {
            if ((IpAdress.charAt(i)) == '.') {
                countPoints++;

            }
            if ((countPoints == point) && IpAdress.charAt(i) != '.') {
                buf.append(IpAdress.charAt(i));
            }

        }
        String result = buf.toString();
        return Integer.parseInt(result);
    }

    public boolean isPrivateNetwork() {

        if (getOctet(0) == 10) {
            return true;
        }

        if (getOctet(0) == 172) {
            if (getOctet(1) >= 16 && getOctet(1) <= 31) {
                return true;
            }
        }

        if (getOctet(0) == 192) {
            if (getOctet(1) == 168) {
                return true;
            }
        }

        return false;

    }


    public IPAddress mask(IPAddress mask){
        int n0= mask.getOctet(0) & getOctet(0);
        int n1= mask.getOctet(1) & getOctet(1);
        int n2=mask.getOctet(2) & getOctet(2);
        int n3=mask.getOctet(3) & getOctet(3);



         IPAddress n1= new IPAddressString (n0,n1,n2,n3);
    }

}

问题再次出现在方法掩码上.我需要返回一个新的IPAddress,但我应该使用我的结构.我错过了什么？

谢谢.

Answer 1

您可以实现IPAddress在IPAddressString.虽然您正在实现类中的所有IPAddress接口方法IPAddressString,但您并没有告诉编译器[显然无法猜测您的意图].

将类的定义更改为:

class IPAddressString implements IPAddress

这应该解决转换中的问题.

现在这一行:

IPAddress n1= new IPAddressString (n0,n1,n2,n3);

自建立层次结构以来,不会给您带来任何问题.你可以安静地回来n1.