IPv6 support in Java

Question

I am trying to test a java program for IPv6 support on my local system having Windows 7 OS. I have assigned an IPv6 address and have disabled IPv4 in Network Connection.

When I execute ipconfig command I get IPv6 address as output.

However, when I execute below java code I get 127.0.0.1 which is an IPv4 address

System.setProperty("java.net.preferIPv6Stack","true");

InetAddress addr = InetAddress.getLocalHost();
System.out.println(addr.getHostAddress());

As per my understanding the above code should print 0:0:0:0:0:0:0:1 .

Have I missed something?

Answer 1

Problem is resolved. I was setting wrong System property. Correct system property that needs to be set is

System.setProperty("java.net.preferIPv6Addresses","true")

After setting this property the IPv6 address assigned in Network Connection will be displayed.

IPv6 loopback address can be retrieved using below code.

InetAddress.getLoopbackAddress().getHostAddress()

Answer 2

You can use Inet6Address class.

java.net.Inet6Address.getHostAddress()

Refer this question. InetAddress.getHostAddress() ipv6 compliant?