Java

Writes, debugs, and tunes Java and the JVM: nulls, equality, collections, generics, concurrency, streams, memory, builds, and upgrades. Use when Java throws NullPointerException, ClassCastException, ConcurrentModificationException, NoClassDefFoundError, NoSuchMethodError, UnsupportedClassVersionError or OutOfMemoryError, when a service deadlocks, hangs, burns CPU, or leaks memory, when equals/hashCode, Optional, generics, streams, or CompletableFuture misbehave, when dates shift or text turns into question marks, when Maven or Gradle resolves the wrong version or a fat jar fails only after pac