Entry-level Java Programming Interview Questions and Answers Fully Solved Graded A+

Entry-level Java Programming Interview Questions and Answers Fully Solved Graded A+ What are the main features of Java? - Answers 1. Object-oriented 2. Simple 3. Platform Independent 4. Secured 5. Robust 6. Portable 7. Multithreaded 8. Distributed What are the fundamental principles of OOP? - Answers 1. Inheritance 2. Abstraction 3. Polymorphism 4. Encapsulation What is Inheritance in Java? - Answers Inheritance is one of the key principles of OOP. Through Inheritance, one class can inherit the properties of another class. The class from which properties are inherited is called a "super" class and the class to which properties are inherited is called a sub class. What is Constructor Overloading and its use? - Answers A class can have any number of constructors. These constructors will have different lists of arguments. It is called constructor overloading. Constructor overloading provides different ways to instantiate a class. What is polymorphism in Java? - Answers Polymorphism refers to any entity whether it is a method, constructor or an operator which takes many forms or can be used for multiple tasks. What is method overloading in Java? - Answers When a class has more than one method with the same name but with different lists of arguments. What is method overriding? - Answers When a super class method is modified in the sub class then it is called method overriding. Does Java support multiple inheritance? - Answers Java supports multiple inheritance only through interfaces. That means a class can implement more than one interface but can not extend more than one class. What is the difference between a constructor and a method? - Answers A constructor is a special member of a class which is used to create the objects of the class. It is special because it will have the same name as the class and will have no return type. A method, however, is an ordinary member of a class which is used to implement some behavior of a class. It will have its own name and return type. Can we overload the main() method? - Answers Yes, we can overload a main() method. A class can have any number of main() methods, but, one of these must be in the form "public static void main(String[] args)" in order to start the execution. How are exceptions handled in Java? - Answers Java has its own mechanism to handle the exceptions. In Java, exceptions are handled using three blocks - Try, Catch, and Finally blocks. Try - The code to be monitored for exceptions will be kept in this block. Catch - If any exceptions occurred in try block, those exceptions must be caught in this block. Finally - This block will always be executed. What are PATH and CLASSPATH? - Answers PATH and CLASSPATH are two environment variables which need to be set in order to compile and run the Java programs. What is the difference between error and exception in Java? - Answers FILL IN LATER What are the differences between static and non-static methods? - Answers Static methods are common to all instances of a class and are stored in the class memory whereas non-static methods are stored in the object memory. Each instance of a class will have their own copy of non-static methods. What are the differences between method overloading and method overriding? - Answers FILL IN LATER What are the different ways of creating threads in Java? - Answers There are 2 ways to create the threads in Java: 1. Extending .Thread class 2. Implementing .Runnable interface