<p>So you have a String that is retrieved from an admin web UI (so it is definitely a String). How can you find out whether this string is an IP address or a hostname in Java?</p>

<p>Update: I think I didn't make myself clear, I was more asking if there is anything in the Java SDK that I can use to distinguish between IPs and hostnames? Sorry for the confusion and thanks for everybody who took/will take the time to answer this.</p>

You can use a regular expression with this pattern:
```
```
\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
```
```
That will tell you if it's an IPv4 address.