Category: uncategories

Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object. Any Java object that can pass more than one IS-A test is considered to be polymorphic. In Java, all Java…

In the previous chapter, we talked about superclasses and subclasses. If a class inherits a method from its superclass, then there is a chance to override the method provided that it is not marked final. The benefit of overriding is: ability to define a behavior that’s specific to the subclass type, which means a subclass…

The class which inherits the properties of other is known as subclass (derived class, child class) and the class whose properties are inherited is known as superclass (base class, parent class). extends Keyword extends is the keyword used to inherit the properties of a class. Following is the syntax of extends keyword. Syntax Sample Code Following…

In this chapter, we will discuss inner classes of Java. Nested Classes In Java, just like methods, variables of a class too can have another class as its member. Writing a class within another is allowed in Java. The class written within is called the nested class, and the class that holds the inner class is…

An exception (or exceptional event) is a problem that arises during the execution of a program. When an Exception occurs the normal flow of the program is disrupted and the program/Application terminates abnormally, which is not recommended, therefore, these exceptions are to be handled. An exception can occur for many different reasons. Following are some scenarios where…

The java.io package contains nearly every class you might ever need to perform input and output (I/O) in Java. All these streams represent an input source and an output destination. The stream in the java.io package supports many data such as primitives, object, localized characters, etc. Stream A stream can be defined as a sequence…

A Java method is a collection of statements that are grouped together to perform an operation. When you call the System.out.println() method, for example, the system actually executes several statements in order to display a message on the console. Now you will learn how to create your own methods with or without return values, invoke a…

Java provides the java.util.regex package for pattern matching with regular expressions. Java regular expressions are very similar to the Perl programming language and very easy to learn. A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a…

Java provides the Date class available in java.util package, this class encapsulates the current date and time. The Date class supports two constructors as shown in the following table. Sr.No. Constructor & Description 1 Date( )This constructor initializes the object with the current date and time. 2 Date(long millisec)This constructor accepts an argument that equals the number of milliseconds…

Java provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type. Instead of declaring individual variables, such as…