In Java, Abstraction is one of the major building block. It is a process of hiding internal working and showing only necessary details. In simple form abstraction means:<\/p>\n
Important Note:<\/strong><\/span> Interface is used to achieve 100% Abstraction in JAVA. Here we only discuss Abstraction in full details but we recommend you to learn Abstraction and Interface topic simultaneously as both topics are similar with little bit difference.<\/p>\n The best explanation of Abstraction is using the common example of sending SMS. When a user send SMS, he simply enter the address, type message in the text box and send it. He doesn\u2019t know what is happening behind the scene when this message is getting send to the other user. So here implementation details has been hided from the user and only functionality is presented to user. This is achieved in JAVA either through Abstraction or Interface.<\/p>\n Before we share syntax you first need to understand abstract class, abstract methods and why\/how to extend Abstract class:<\/p>\n What Is Abstract Class:<\/strong><\/span><\/p>\n An abstract class is declared with abstract keyword which may contain methods without body, with body or mixture of both. If a class have at least one method without body then it has to be declared abstract.<\/p>\n Important Note:<\/strong><\/span> Method without body means method without any functionality or implementation.<\/p>\n In the below example you can see one method calling is without body. So here class has to be declared abstract because it has one method without body.<\/p>\n What Is Abstract Method:<\/strong><\/span><\/p>\n The methods without body or methods with only signatures are called abstract methods. The abstract method doesn\u2019t have any implementation details. It is declared using abstract keyword before method name. For example, calling method is an abstract method.<\/p>\n Syntax: of Abstract Method <\/strong><\/p>\n Important Note:<\/strong><\/span> In order to use abstract method we first need to override that method in subclass (i.e. child class).<\/p>\n Why And How To Extend Abstract Class:<\/strong><\/span><\/p>\n As now you already know Abstract class may contains abstract method without any implementation and thus we cannot instantiate abstract class. In case we try instantiating it, the object might be useless because methods inside abstract class may not have any implementation at all. So to avoid this situation, JAVA doesn\u2019t allow us to instantiate abstract class.<\/p>\n We first need to extend abstract class where we will do the implementation of those abstract method and then we instantiate this new class.<\/p>\n So let\u2019s see how to extend Abstract class:<\/strong><\/p>\n Step 1:<\/strong><\/span> First we define abstract class with abstract method:<\/p>\n Step 2:<\/strong><\/span> Now we extends abstract class and implement abstract methods:<\/p>\n Pro Note:<\/strong><\/span> An example of abstract class is AbstractMap which is part of collection framework include TreeMap, HashMap and ConcurrentHashMap and share many methods like isEmpty(), put() , get(), containValue() , containKey() etc that AbstractMap defines.<\/p>\n The syntax of abstraction start with abstract keyword before class name. It then contains mixture of abstract and non-abstract methods.<\/p>\n Example 1:<\/strong><\/span> Lets now understand abstraction concept using real life examples of different sounds created by animals. For example Cat does Meow and Lion Does Roar. We will display different sounds using Abstraction in JAVA.<\/p>\n Step 1:<\/strong> First create a new project in Eclipse and create a abstract class Sound. Below is the code of Sound.java<\/p>\n Step 2:<\/strong> Now create another class name Cat which extends Sound class. Here we will implement abstract sound() method for Cat. Below is the code of Cat.java<\/p>\n Step 3:<\/strong> In the same way we are creating another Lion class which extends Sound class. Here also we will implement the sound() method but for Lion. Below is the code of Lion.java:<\/p>\n Step 4:<\/strong> Now create AnimalSound main class. Here first we will create object of Cat & Lion class and then we will call sound() method on these objects. Below is the code of AnimalSound.java<\/p>\n Output:<\/strong><\/span><\/p>\n Now run the program and you will see sounds of Cat and Lion printed.<\/p>\n Conclusion:<\/strong><\/span> So you can see how useful is Abstraction. We just define mixture of abstract and non-abstract methods in Abstract class and then implement abstract method in child class (i.e. sub class) according to requirement. In the end same method gives different result depending on Objects of which sub-class. Remember we can’t instantiate Abstract class as discussed earlier.<\/p>\n Example 2:<\/strong><\/span> In second Abstraction example we simply display a text “AbhiAndroid” by using an abstract method of an abstract Base class. In this, Child class extends the Base class and override the display method and then prints the text as shown in below example.<\/p>\n Here in this example we have provided lots of explanation in the code itself as comments.<\/p>\n Below is the code of Base.java<\/strong><\/p>\n Below is the code of Child.java and also main function of class<\/strong><\/p>\n OUTPUT:<\/strong><\/span><\/p>\n Conclusion:<\/strong><\/span> In the above example, Base is abstract class that contain abstract method display(). Its implementation is provided by the Child class.<\/p>\n Below is the some major important points of abstraction in java.<\/p>\n Abstract class is quite similar to interface like both contain abstract method and also we can\u2019t initiate both of them. But below are the some key differences between\u00a0 both the topics:<\/p>\n Abstract class:<\/u><\/strong><\/span><\/p>\n Interface:<\/u><\/strong><\/span><\/p>\n In Java, Abstraction is one of the major building block. It is a process of hiding internal working and showing only necessary details. In simple form abstraction means: Show Functionality Hide Complexity Important Note: Interface is used to achieve 100% Abstraction in JAVA. Here we only discuss Abstraction in full details but we recommend you … Continue reading Abstraction Tutorial With Example In JAVA<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"home.php","meta":{"footnotes":""},"class_list":["post-518","page","type-page","status-publish","hentry"],"psp_head":"
\nExplanation Of Abstraction:<\/strong><\/h4>\n
\nKey Learning Points On Abstraction:<\/strong><\/h4>\n
abstract class Mobile{\r\nabstract void calling();\r\nabstract void messaging()\r\n{\r\nSystem.out.println(\"Messaging\");\r\n}\r\n}<\/pre>\nabstract void calling();<\/pre>\n
abstract void method_name();<\/pre>\n
abstract class Mobile{\r\nabstract calling(); \/\/Method without body\r\n}<\/pre>\nclass Samsung extends Mobile{\r\nvoid calling();\r\n{\r\nSystem.out.println(\"Start Calling\");\r\n}\r\n}<\/pre>\n
\nSyntax Of Abstraction:<\/strong><\/h4>\n
abstract class <ClassName>{\r\n\/\/Mixture of abstract methods(Without body\/implementation) and non-abstract methods(with body\/implementation)\r\n\/\/If it contains atleast one abstract method then a class has to be declared abstract\r\n}<\/pre>\n
\nExamples Of Abstraction:<\/strong><\/h4>\n
abstract class Sound {\r\n\u00a0\u00a0 \u00a0\r\n\/\/Non-abstract method i.e. method with implementation\r\n\u00a0\u00a0 \u00a0public void soundmessage(){\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0System.out.print(\"Animal Sound\");\r\n\u00a0\u00a0 \u00a0}\r\n\u00a0\u00a0 \u00a0\r\n\/\/Abstract method i.e. without body\/implementation\r\n\u00a0\u00a0 \u00a0abstract void sound();\r\n\r\n}<\/pre>\nclass Cat extends Sound{\r\n\r\nvoid sound(){\r\n\tsoundmessage();\r\n\tSystem.out.println(\" of Cat: Meow\");\r\n}\r\n\r\n}<\/pre>\nclass Lion extends Sound {\r\n\t\r\n\tvoid sound(){\r\n\t\tsoundmessage();\r\n\t\tSystem.out.println(\" of Lion: Roar\");\r\n\t}\r\n\r\n}<\/pre>\npublic class AnimalSound {\r\n\r\n\tpublic static void main(String[] args) {\r\n\t\t\r\n\t\tCat cat = new Cat();\r\n\t\tcat.sound();\r\n\t\t\r\n\t\tLion lion = new Lion();\r\n\t\tlion.sound();\r\n\t}\r\n\r\n}<\/pre>\nAnimal Sound of Cat: Meow\r\nAnimal Sound of Lion: Roar<\/pre>\n
abstract class Base \/\/abstract class\r\n{\r\nabstract void display(); \/\/abstract method\r\n}<\/pre>\nclass Child extends Base \/\/child class which extends the property of base class\r\n{\r\nvoid display() \/\/ override method of base class\r\n {\r\n System.out.println(\"AbhiAndroid\"); \/\/prints the text \u201cAbhiAndroid\u201d as an output\r\n}\r\npublic static void main(String args[]) \/\/main function of class\r\n{\r\n Child c=new Child(); \/\/create an object of child class\r\n c.display(); \/\/call the display method of child class with the help of object\r\n}\r\n}<\/pre>\nAbhiAndroid<\/pre>\n
\nImportance Of Abstraction<\/strong><\/h4>\n
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\nDifference Between Abstract Class And Interface:<\/strong><\/h4>\n
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