title: Using Java Decompiler (JD-GUI) on a .class file gives me multiple errors on src file, but it runs fine within a .jar? How does it work?
body: <p>I'm new to Java and I'm trying to understand something. I managed to get a .jar file for a local device to communicate with my laptop. It works fine, but I would like to do an upgrade and scoop around the codes and change some details. I used a Java Decompiler on the .jar file and managed to take a look at the class files. However, whenever I decompile them into source codes, errors will occur in my IDE, and I'm unable to build them. What exactly happened? If it's working fine in the .jar why does it produce errors?</p>