Top 5 Java troll moments

1. Memory limit is not a real memory limit 🤔
   • I can define heap memory limit for the JVM... But the actual memory usage can end up being 10% higher, or 20%, or even 50% higher, because native memory allocations are not counted as heap memory
   • My app will use all available memory inside the container and crash, even though I thought I set a limit... What?
   • At this point, why even have a memory limit at all?
2. Reserved words that do nothing 🅰️
   • const is a reserved keyword, but I cannot define a constant value with it
   • _ underscore is also a reserved keyword, but it cannot be used until Java 25. It took 10+ years from keyword introduction to actual implementation. No way... Better later than never?
3. Character to number implicit casting 🔟
   • It is possible to create string builder from character: new StringBuilder('a'). But 'a' will be treated as integer 97. What the heck...
4. ForkJoinPool.commonPool() 📊
   • The number of available threads is limited to the number of CPU threads
   • If some tasks spawn other tasks, then I will run out of threads and enter a deadlock... Or not, if I am lucky enough to run on a multicore CPU with enough cores
   • No error message, only infinite waiting
5. Check if two objects are equal 🍏
   • Compare two strings using == operator, a beginner's mistake
   • Or compare two objects using a.equals(b), only to find out that the objects belong to different classes, and cannot be equal ever
   • These errors can only be caught effectively with a good linter. Compiler will say nothing about those errors
   • Bonus headache if one of the objects is null, calling null.equals()