Posts

What is Multithreading in java step by step example

Image
Java provides built-in support for multithreaded programming . A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution. A multithreading is a specialized form of multitasking. Multithreading requires less overhead than multitasking processing. I need to define another term related to threads: process: A process consists of the memory space allocated by the operating system that can contain one or more threads. A thread cannot exist on its own; it must be a part of a process. A process remains running until all of the non-daemon threads are done executing. Multithreading enables you to write very efficient programs that make maximum use of the CPU, because idle time can be kept to a minimum. Life Cycle of a Thread: A thread goes through various stages in its life cycle. For example, a thread is born, started, runs, and then dies. Following diagram s
Post a Comment
Read more

Java Inheritance with step by step example

Image
Inheritance can be defined as the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order. When we talk about inheritance the most commonly used keyword would be extends and implements . These words would determine whether one object IS-A type of another. By using these keywords we can make one object acquire the properties of another object. IS-A Relationship: IS-A is a way of saying : This object is a type of that object. Let us see how the extends keyword is used to achieve inheritance. public class Animal { } public class Mammal extends Animal { } public class Reptile extends Animal { } public class Dog extends Mammal { } Now based on the above example, In Object Oriented terms following are true: Animal is the superclass of Mammal class. Animal is the superclass of Reptile class. Mammal and Reptile are sub classes of Animal class. Dog is the subcl
Post a Comment
Read more

Java Interfaces step by step solution with example

An interface is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface. An interface is not a class. Writing an interface is similar to writing a class, but they are two different concepts. A class describes the attributes and behaviors of an object. An interface contains behaviors that a class implements. Unless the class that implements the interface is abstract, all the methods of the interface need to be defined in the class. An interface is similar to a class in the following ways: An interface can contain any number of methods. An interface is written in a file with a .java extension, with the name of the interface matching the name of the file. The bytecode of an interface appears in a .class file. Interfaces appear in packages, and their corresponding bytecode file must be in a directory structure that matches the package name. However, an interface is different from a class in several ways,
Post a Comment
Read more

Java Encapsulation step by step solution with example

Encapsulation is one of the four fundamental OOP concepts. The other three are inheritance, polymorphism, and abstraction. Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding. Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface. The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code. Example: Let us look at an example that depicts encapsulation: /* File name : EncapTest.
Post a Comment
Read more

Java Abstraction step by step example

Abstraction refers to the ability to make a class abstract in OOP. An abstract class is one that cannot be instantiated. All other functionality of the class still exists, and its fields, methods, and constructors are all accessed in the same manner. You just cannot create an instance of the abstract class. If a class is abstract and cannot be instantiated, the class does not have much use unless it is subclassed. This is typically how abstract classes come about during the design phase. A parent class contains the common functionality of a collection of child classes, but the parent class itself is too abstract to be used on its own. Abstract Class: Use the abstract keyword to declare a class abstract. The keyword appears in the class declaration somewhere before the class keyword. /* File name : Employee.java */ public abstract class Employee { private String name ; private String address ; private int number ; public Employee ( String name
Post a Comment
Read more

Java Overriding with step by step example

In the previous chapter we talked about super classes and sub classes. If a class inherits a method from its super class, 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 sub class type. Which means a subclass can implement a parent class method based on its requirement. In object oriented terms, overriding means to override the functionality of any existing method. Example: Let us look at an example. class Animal { public void move (){ System . out . println ( "Animals can move" ); } } class Dog extends Animal { public void move (){ System . out . println ( "Dogs can walk and run" ); } } public class TestDog { public static void main ( String args []){ Animal a = new Animal (); // Animal reference and object Animal b = new Dog (); // Animal reference but Dog
Post a Comment
Read more

Java Packages step by step solution with example ( what is Packages in java )

Packages are used in Java in-order to prevent naming conflicts, to control access, to make searching/locating and usage of classes, interfaces, enumerations and annotations easier etc. A Package can be defined as a grouping of related types(classes, interfaces, enumerations and annotations ) providing access protection and name space management. Some of the existing packages in Java are:: java.lang - bundles the fundamental classes java.io - classes for input , output functions are bundled in this package Programmers can define their own packages to bundle group of classes/interfaces etc. It is a good practice to group related classes implemented by you so that a programmers can easily determine that the classes, interfaces, enumerations, annotations are related. Since the package creates a new namespace there won't be any name conflicts with names in other packages. Using packages, it is easier to provide access control and it is also easier to locate the rela
Post a Comment
Read more