On http://java.sun.com/j2se/1.5.0/docs/api/java/net/URL.html it states that:

Compares this URL for equality with another object.

If the given object is not a URL then this method immediately returns false.

Two URL objects are equal if they have the same protocol, reference equivalent hosts, have the same port number on the host, and the same file and fragment of the file.

Two hosts are considered equivalent if both host names can be resolved into the same IP addresses; else if either host name can't be resolved, the host names must be equal without regard to case; or both host names equal to null.

Since hosts comparison requires name resolution, this operation is a blocking operation.

Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP.

According to this, equals will only work if name resolution is possible. Since I can't be sure that a computer has internet access at a given time, should I just use Strings to store addresses instead? Also, how do I go about testing if access is available when requested?