You'll want the OptionManager object on the ServiceInstance.

ServiceInstance -> setting ['VirtualCenter.InstanceName']

Thank you very much, but i still have a problem.

This is my code:

ServiceInstance si = new ServiceInstance(url, username, password, ignoreCert);

OptionManager om = si.getOptionManager();

OptionValue[] ovs =om.queryOptions("VirtualCenter.InstanceName");

It returns this error on the third line:

Exception in thread "main" com.vmware.vim25.NoPermission

Also, this instruction:

OptionValue[] ovs =om.getSetting();

returns a NullPointerException...

Where is the problem?

You'll need to login.  If you are logging in, you also need permissions:

This method might require any of the following privileges depending on where the property fits in the inventory tree.

• System.View on the root folder, if this is used to read settings in the "client" subtree.
• System.Read on the root folder, if this is used to read all settings or any settings beside those in the "client" subtree.
• System.Read on the host, if this is used to read the advanced options for a host configuration.