Java Fundamentals

Abstraction refers to the act of representing essential features without including the background details or explanations.

Java provides access modifiers to set access levels for classes, variables, methods and constructors. 

Accessible only by the objects in the same package.

Encapsulation is a technique used for hiding the properties and behaviours of an object and allowing outside access only as appropriate. It prevents other objects from directly altering or accessing the properties or methods of the encapsulated object.

An error indicates that a non-recoverable condition that has occurred that cannot be caught and taken care of. Error is a sub class of Throwable class.

An exception is an event, which occurs during the execution of a program, that discontinues the normal flow of program and prevents the program from executing further.

Inheritance allows a Child class to inherit properties from its parent class. In Java this is achieved by using extends keyword. Only properties with access modifier public and protected can be accessed in child class.

 A Java compiler generated intermediate code, which can execute on any OS, regardless of its OS

JDBC is a Java API that is used to connect and execute query to the database. JDBC API uses jdbc drivers to connects to the database.

JDBC Driver is a software component that enables java application to interact with the database.

It is an acronym for Java Development Kit. It is basically a complete set of development tools necessary for developing & executing Java programs. It contains JRE in itself.

Just-In-Time(JIT) compiler used to improve the performance.

It stands for Java Runtime Environment. It is the implementation of JVM.

It is an abbreviation for Java Virtual Machine, it is an abstract machine (a software) which provides the runtime environment in which java bytecode can be executed. 

A NullPointerException is thrown when calling the instance method of a null object, accessing or modifying the field of a null object etc.

A package is a group of similar type of classes interfaces

Polymorphism is briefly decsribed as "one interface, many implementations". Polymorphism is a characteristic of being able to assign a different meaning or usage to something in different contexts - specifically, to allow an entity such as a variable, a function, or an object to have more than one form.

Variables, methods and constructors which are declared protected in a superclass can be accessed only by the subclasses in other package or any class within the package of the protected members's class

Serialization is a mechanism by which you can save the state of an object by converting it to a byte stream.

It is used to call the base class's method or constructor

 It refers to the currently calling object of the class, mainly used to refer to class members from inside a method when local variable names and member variable names are identical to each other.