FULL PRODUCT VERSION :
1.8.0_20-b26

ADDITIONAL OS VERSION INFORMATION :
2.6.32-431.11.2.el6.x86_64

EXTRA RELEVANT SYSTEM CONFIGURATION :
/etc/hosts contains as first line:

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 <actual computer name as seen on local network>

Java is run with option -Djava.net.preferIPv4Stack=true

A DESCRIPTION OF THE PROBLEM :
InetAddress.getLocalhost().getHostName() returns "localhost" when using java8, while it returns the actual computer name as seen on local network with java 7.

If I change my /etc/hosts file to have the actual computer name as seen on local network as first alias (before localhost) for address 127.0.0.1 then the problem doesn't occur any more (e.g. I get the actual computer name, not localhost, on either java versions)

REGRESSION. Last worked in version 7u51

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run java with option -Djava.net.preferIPv4Stack=true

use a /etc/hosts file that contains localhost as first alias for 127.0.0.1 and the actual computer name as last alias on the line.

run a program that prints the result of InetAddress.getLocalhost().getHostName();

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
actual computer name as seen on network
ACTUAL -
localhost

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.concurrent.TimeUnit;

import org.junit.Test;

public class ShowInetAddress {

public void main(String[] args) {
try {
System.out.println(InetAddress.getLocalHost());
} catch (UnknownHostException ex) {
ex.printStackTrace();
}

}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
put the actual computer name as first alias for 127.0.0.1 (e.g. write it before localhost) in the /etc/hosts file