How to decompile a DEX file back into Java source code?

Hello, colleagues! I'm new to Android development and reverse engineering. I've encountered a task: I have an APK file (a regular Android app), and I want to see how some logic inside works. I know that Java bytecode (JVM) is compiled into DEX (Dalvik Executable) for Android. But how do I get readable Java code back from this DEX? I tried simply opening the APK as a ZIP archive and finding classes.dex, but it's a binary file, unreadable. I tried converting DEX to JAR using the dex2jar utility, and then opening the JAR in a decompiler (e.g., JD-GUI). In some cases this works, but often the code comes out obfuscated (a, b, c instead of variable names) or even breaks entirely. Here's an example of what I see after decompilation: ```java public class a { public static String ```