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

You can declare local variables within any method. The example code below declares a local variable in the AlarmClock snooze() method: public class AlarmClock { public void snooze() { ...

Abstract classes and interfaces in Java serve fundamentally different purposes. Learn the differences between these Java language elements and how to use them in your programs.