Java Memory Management: Avoiding OutOfMemoryErrors

My worst production moment was at 3 AM on a Saturday. The application started throwing `OutOfMemoryError`. The heap was full, and the GC was thrashing. I had to restart it, but it happened again two days later. I learned that day that you can’t just set `-Xmx1024m` and hope for the best. You need to monitor. Tools like VisualVM and JProfiler are lifesavers. Most memory leaks in Java come from holding onto references you no longer need—like adding objects to a static collection and forgetting to remove them. Also, while Strings are optimized, concatenating large strings in a loop using `+` creates many intermediate objects. Use `StringBuilder` in those cases. If you’re using a lot of caching, make sure to use soft or weak references so the GC can reclaim memory when needed. Memory management is a dark art, but understanding it is what keeps you from getting paged on weekends.