Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
What is the easiest way in Java 6 to determine whether a given address is a valid net mask? I have found one solution which basically creates an array of valid IPs to use in a comparison (i.e. “255.255.255.255”, “255.255.255.254”, “255.255.255.252”, etc…). Is there an easier way or is this the best way?
If you’re happy to include an external dependency, then Apache’s commons.net may have what you’re looking for.
Have a look at SubnetUtils and its SubnetInfo nested class. You can construct a
SubnetUtilswith an IP address and a mask. The constructor throws an exception if your mask is invalid, and SubnetInfo.html#isInRange can tell you if an IP is in a mask’s range.