Core Java Questions and Answer for Interview

21. Does the order of public and static declaration matter in main() method?
No. It doesn't matter but void should always come before main().

22. Can a source file contain more than one class declaration?
Yes a single source file can contain any number of Class declarations but only one of the class can be declared as public.

23. What is a package?
Package is a collection of related classes and interfaces. package declaration should be first statement in a java class.

24. Which package is imported by default?
java.lang package is imported by default even without a package declaration.

25. Can a class declared as private be accessed outside it's package?
Not possible.

26. Can a class be declared as protected?
The protected access modifier cannot be applied to class and interfaces. Methods, fields can be declared protected, however methods and fields in a interface cannot be declared protected.

27. What is the access scope of a protected method?
A protected method can be accessed by the classes within the same package or by the subclasses of the class in any package.

28. What is the purpose of declaring a variable as final?
A final variable's value can't be changed. final variables should be initialized before using them.

29. What is the impact of declaring a method as final?
A method declared as final can't be overridden. A sub-class can't have the same method signature with a different implementation.

30. I don't want my class to be inherited by any other class=What should i do?
You should declared your class as final. But you can't define your class as final, if it is an abstract class=A class declared as final can't be extended by any other class.