InetAddress :无法初始化

Question

由于某些原因，我似乎无法初始化InetAddress对象，我查看了文档，它与我使用它的方式完全一样。

 InetAddress firstMachineAddress = InetAddress.getByName("129.26.70.95");
 InetAddress secondMachineAddress = InetAddress.getByName("129.26.70.108");

Eclipse说：

Default constructor cannot handle exception type UnknownHostException thrown by implicit super constructor. Must define an explicit constructor

到底是怎么回事？

Answer 1

您的代码似乎位于由另一个类扩展的类的构造函数中，如下所示：

import java.net.*;

class SuperclassWithUnknownHostException {
    public SuperclassWithUnknownHostException() throws UnknownHostException {
        InetAddress firstMachineAddress = InetAddress.getByName("129.26.70.95");
        InetAddress secondMachineAddress = InetAddress.getByName("129.26.70.108");
    }
}

class SubclassCannotHandleException extends SuperclassWithUnknownHostException {

}

您需要向引发异常的子类添加一个默认构造函数：

class SubclassCannotHandleException extends SuperclassWithUnknownHostException {
    public SubclassCannotHandleException() throws UnknownHostException {

    }
}

Answer 2

您正在处理调用的方法引发的UnknownHostException吗？

InetAddress firstMachineAddress;
try {
    firstMachineAddress = InetAddress.getByName("129.26.70.95");
} catch (UnknownHostException e) {
    // print exception, throw error,
    // try something else etc.
}

Answer 3

inetAddress对象为一个异常抛出一个异常，因此您需要在它周围包装一个尝试捕获，或者让您的方法也抛出一个异常。此外，我相信您正在得到错误，因为有一个异常回来，您没有处理。getByName()方法使用www.google.com或www.amazon.com等and地址名称的字符串参数。

try{
        InetAddress Address = InetAddress.getByName("www.google.com"); 
        System.out.println(Address);
    }catch(UnknownHostException e){
        e.printStackTrace();
    }

这显示www.google.com/64.233.177.147