I want to hide the links to my server address in my Android app. When my app is decompiled, the links are clearly showing. Even with the proguard enabled I am not able to hide links. How can I protect these links?
This is a fool's errand. Even if you you could obfuscate them sufficiently in the source code, it would still be child's play to hook the device up to a proxy like Fiddler or Burp Suite, and see the raw URLs plain as day when the app is running. No need to look at your source code at all, and there is absolutely nothing you can do about protecting HTTP requests, and even HTTPS requests in this case, for several reasons.
So, was suggested in the comment, you need to protect the endpoints exposed by your server via authentication and authorization. Disguising the address is simply not a viable option.