how to understand NetworkInterface and InetAddress concept?

Question

I think in java, NetworkInterface is abstraction of network card . If this is right , why one NetworkInterface contains more than one InetAddress ?

for example this code in my macbook :

NetworkInterface en0 = NetworkInterface.getByName("en0");
Enumeration<InetAddress> adrs = en0.getInetAddresses() ;
while(adrs.hasMoreElements()){
    InetAddress adr = adrs.nextElement();
    System.out.println(adr.getHostAddress());
}

Output:

fe80:0:0:0:7a31:c1ff:feb7:a3a2%4
192.168.1.100

There are two address, but I didn't use IPv6.

My question is that, how to understand this two concepts? What's their relationship?

Answer 1

why one NetworkInterface contains more than one InetAddress?

Because you can configure an NIC with multiple addresses. This has been the case for about twenty years.

I didn't use IPv6

Somebody did. Maybe you're using DHCP and it came from there.