The essence of an abstract class in Java Abstract classes can have state with instance variables. This means that an instance variable can be used and mutated. Here’s an example: ...

Java SE 10 (March 2018) introduced type inference for local variables. Java Language Architect Brian Goetz explains the feature.

Tip: Unlike class and instance field variables, threads cannot share local variables and parameters. The reason: Local variables and parameters allocate on a thread’s method-call stack.