java-fixlisted

Diagnose the Java error or stack trace I've provided and propose a fix. Be specific — do not give generic advice. ## Step 1 — Identify the error type **Compile errors (javac / Maven / Gradle output):** - `cannot find symbol` → missing import, misspelled name, or wrong scope - `incompatible types` → type mismatch; check generics, autoboxing, widening - `method X is not applicable` → wrong number or types of arguments - `variable X might not have been initialized` → missing initialisation on all code paths - `reached end of file while parsing` → unmatched `{` or `}` - `class X is public, should be declared in a file named X.java` → filename mismatch **Runtime exceptions (stack traces):** - `NullPointerException` → identify the line; determine which reference is null; suggest a null check or Optional - `ClassCastException` → show the actual vs expected type; fix the cast or use instanceof first - `ArrayIndexOutOfBoundsException` → check loop bounds and array length - `StackOverflowError` → identify the recursive call; check base case - `ConcurrentModificationException` → iterating and modifying a collection simultaneously; suggest iterator.remove() or a copy - `IllegalArgumentException` / `IllegalStateException` → read the message; check the API contract ## Step 2 — Find the root cause Read the full error message carefully. The root cause is usually the last "Caused by:" in a stack trace. Show the user: 1. The exact line causing the error (if visible in the stack trace) 2. W