InetAddress类中的getAddress()方法的返回值为什么直接是null？

问题描述：

正在学习java的socket编程。在看源码时候发现，InetAddress类中的getAddress()方法的返回值为null；
表示很蒙圈，望大神能解答

答

public static void main(String[] args) throws UnknownHostException {
InetAddress address = InetAddress.getLocalHost();
System.out.println("this is address:" + address);

    String hostName = address.getHostName();
    String hostAddress = address.getHostAddress();
    System.out.println("this is host name:" + hostName);
    System.out.println("this is host address:" + hostAddress);

    byte[] address4Byte = address.getAddress();
    System.out.println("this is address4Byte len:" + address4Byte.length);
    for (int i = 0; i < address4Byte.length; i++) {
        System.out.print(address4Byte[i]);
    }
}

这是楼主写的测试方法。我用byte[] address4Byte指向了address.getAddress();这个方法，但是address.getAddress();返回值是null；
但还是能获取到我的主机地址，这是为什么呢？

答

import java.net.InetAddress;
import java.net.UnknownHostException;

public class AA {

/**
 * @param args
 */
public static void main(String[] args) {
    InetAddress address = null;
    try {
        address = InetAddress.getLocalHost();
    } catch (UnknownHostException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    System.out.println("this is address:" + address);

        String hostName = address.getHostName();
        String hostAddress = address.getHostAddress();
        System.out.println("this is host name:" + hostName);
        System.out.println("this is host address:" + hostAddress);

        byte[] address4Byte = address.getAddress();
        System.out.println("this is address4Byte len:" + address4Byte.length);
        for (int i = 0; i < address4Byte.length; i++) {
            System.out.print(address4Byte[i]);
        }

}

}

我运行没有错误的

InetAddress类中的getAddress()方法的返回值为什么直接是null？

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