Implicit narrowing(for final constant) occurs only for byte, char, short, and int. Remember that it does not occur for long, float, or double.

Method-local inner classes cannot be defined using explicit access modifiers (public, protected and private) but non-access modifiers: final and abstract can be used with method-local inner class. Static also not allowed.

a method local inner class can access local variables and parameters of the enclosing block that are final or effectively final.

• The of and copyOf methods do not support null elements.

• The class Exception and any subclasses that are not also subclasses of RuntimeException are checked exceptions. Checked exceptions need to be declared in a method or constructor's throws clause if they can be thrown by the execution of the method or constructor and propagate outside the method or constructor boundary.

• java.lang.Exception is a checked Exception

• Though an interface is allowed to have overriding abstract methods [equals(Object) method, toString() method etc.] from Object class but default methods of an interface cannot override the methods of the Object class.
• Interfaces in java are allowed to override default method with abstract method and vice versa.
• An Interface can extend an interface and override the abstract method with default interface.
• a default method cannot be overridden by a static method.
  • cannot override a non-static method with a static method and vice versa in a class.
  • static methods are never overridden, they may be hidden by a "static method of a subclass" with the same signature.
• You can, however, redeclare a static method of a super interface as a default method in the sub interface
  • because a static method of an interface can only be called using that interface's name.
    • (note: static methods cannot be overridden by an instance method).
    • because "A class cannot have two methods with the same signature in its scope where one is static and one is instance."