Interview prep | Level 3

1. What types of nested classes are there? There are four kinds of nested class in Java. In brief, they are: • static class: declared as a static member of another class • inner class: declared as an instance member of another class • local inner class: declared inside an instance method of another class • anonymous inner class: like a local inner class, but written as an expression which returns a one-off object 2. What does an anonymous class become when it is compiled? Byte codes for anonymous classes are created at compile time. Anonymous classes are named after their enclosing class, postponed with the $ sign and an increasing number - Foo$1.class 3. Why use the keyword final when creating anonymous classes? The reason why the access has been restricted only to the local final variables is that if all the local variables would be made accessible then they would first required to be copied to a separate section where inner classes can have access to them and maintaining multiple copies of mutable local variables may lead to inconsistent data. Whereas final variables are immutable and hence any number of copies to them will not have any impact on the consistency of data. 4. What is the right way to create an instance of a nested inner class? Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes: class OuterClass { ... class InnerClass { ... } } An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance. To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax: OuterClass outerObject = new OuterClass() OuterClass.InnerClass innerObject = outerObject.new InnerClass();

Anyone knows answer for the question no.7?

Some of these questions don't make sense, or at least I can't understand them. For example: 3. Why use the keyword final when creating anonymous classes? - nowhere in this article https://codegym.cc/groups/posts/261-anonymous-classes does it talk about this. And nowhere on the internet have I found mentions of using the final keyword when creating anonymous classes ? 5. What is the right way to create an instance of a nested class? - nested classes can be either static or non-static no? Which type of a nested class are they referring to here? Isn't this question the same as number 4?

10-A static nested class can only access the static fields of an outer class and can be independently created without creating the outterClass object first.(an anonymous class cannot contain static variables and methods because it inheret from it's ancestor (inner class)!) so false