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abstract class java

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Innocent Iguana answered on January 8, 2020 Popularity 9/10 Helpfulness 1/10

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abstract class java

Comment

abstract class Animal { // Base abstract class
  public abstract void animalSound(); // This is the abstract method in base class
  protected int ageInMonth(int ageInYears){ // shared implementation for derived class
    return ageInYears*12;
  }
}

class Cat extends Animal {
  @Override  				
  public void animalSound() {
    System.out.println("Mew"); // Abstract must be implemented in derived class
  }
}

abstract class Dog extends Animal {		// The derived class is also abstract class		
    // No need for animalSound() method since this class is an abstract class
}

class Main {
  public static void main(String[] args) {
    var myAnimal = new Animal();  // Invalid, abstract class cannot be instantiated
    var myCat = new Cat();  // valid
    var myDog = new Dog();   // Invalid, abstract class cannot be instantiated

    myCat.animalSound(); // Forced Polymorphed behavior in derived class 1
  }
}

Popularity 9/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: abstract-class java

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Contributed on Aug 08 2023

Innocent Iguana

0 Answers Avg Quality 2/10

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abstract class in java

Comments(2)

155

Sometimes we may come across a situation where we cannot provide 
implementation to all the methods in a class. We want to leave the 
implementation to a class that extends it. In such case we declare a class
as abstract.To make a class abstract we use key word abstract. 
Any class that contains one or more abstract methods is declared as abstract. 
If we don’t declare class as abstract which contains abstract methods we get 
compile time error.
  
  1)Abstract classes cannot be instantiated
  2)An abstract classes contains abstract method, concrete methods or both.
  3)Any class which extends abstract class must override all methods of abstract
    class
  4)An abstract class can contain either 0 or more abstract method.

Popularity 10/10 Helpfulness 4/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Nov 30 2020

Thankful Tuatara

0 Answers Avg Quality 2/10

how to create object of abstract class in java

Comment

We cannot create objects of an abstract class. To implement features of an abstract class, we inherit subclasses from it and create objects of the subclass. A subclass must override all abstract methods of an abstract class. However, if the subclass is declared abstract, it's not mandatory to override abstract methods.

Popularity 10/10 Helpfulness 3/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Dec 30 2021

Troubled Teira

0 Answers Avg Quality 2/10

abstract class in java

Comment

public abstract class Animal {
    private String name;

    public Animal(String name) {
        this.name = name;
    }

    public void eat() {
        System.out.println(name + " is eating.");
    }

    public abstract void makeSound(); // Abstract method
}

Popularity 9/10 Helpfulness 3/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Dec 24 2023

sam9934

0 Answers Avg Quality 2/10

java abstract

Comment

public abstract class Shape {
    // Abstract method without implementation
    public abstract double area();

    // Concrete method with implementation
    public void display() {
        System.out.println("This is a shape.");
    }
}

Popularity 8/10 Helpfulness 2/10 Language java

Source: chat.openai.com

Tags: abstract java j

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Contributed on Jan 28 2024

Savindi Dadallage

0 Answers Avg Quality 2/10

abstract class in java

Comment

/*Abstract class:
A class which is declared as abstract is known as an abstract class. 
It can have abstract and non-abstract methods. It needs to be extended 
and its method implemented. It cannot be instantiated.

*/

// Example of abstract class
abstract class A{}  
// Example of Abstract class that has an abstract method
abstract class Bike{  
  abstract void run();  
}  
class Honda4 extends Bike{  
void run(){System.out.println("running safely");}  
public static void main(String args[]){  
 Bike obj = new Honda4();  
 obj.run();  
}  
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: www.javatpoint.com

Tags: abstract-class abst

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Contributed on Jun 18 2022

Rasel Ahmed

0 Answers Avg Quality 2/10

abstract class java constructor

Comment

/**
 * Simple Java program to prove that abstract class can have constructor in Java.
 * @author http://java67.blogspot.com
 */
public class AbstractConstructorTest {

    public static void main(String args[]) {
       Server server = new Tomcat("Apache Tomcat");
       server.start();
    }
}

abstract class Server{
    protected final String name;
   
    public Server(String name){
        this.name = name;
    }
   
    public abstract boolean start();
}

class Tomcat extends Server{
   
    public Tomcat(String name){
        super(name);
    }

    @Override
    public boolean start() {
       System.out.println( this.name + " started successfully");
       return true;
    }
   
}

Output:
Apache Tomcat started successfully

Popularity 10/10 Helpfulness 2/10 Language java

Source: www.java67.com

Tags: abstract-class abst

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Contributed on May 18 2020

Easy Emu

0 Answers Avg Quality 2/10

how to use an abstract class in java

Comment

interface methods{
    public void hey();
    public void bye();
}

//unable to implement all the abstract methods in the interface so 
// the other class automatically becomes abstract
abstract class other implements methods{
    public void hey(){
        System.out.println("Hey");
    }
}

//able to implement all the methods so is not abstract
class scratch implements methods {
    public void hey(){
        System.out.println("Hey");
    }
    public void bye() {
        System.out.println("Hey");
    }
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Jan 08 2020

Nitbit25

0 Answers Avg Quality 2/10

Java Abstract Class and Method

Comment

abstract class Language {

  // method of abstract class
  public void display() {
    System.out.println("This is Java Programming");
  }
}

class Main extends Language {
  public static void main(String[] args) {
    
    // create an object of Main
    Main obj = new Main();

    // access method of abstract class
    // using object of Main class
    obj.display();
  }
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on May 24 2022

SAMER SAEID

0 Answers Avg Quality 2/10

how to create an abstract class in java

Comment

abstract class scratch{
  
}

Popularity 10/10 Helpfulness 1/10 Language java

Source: Grepper

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Contributed on Jan 08 2020

Nitbit25

0 Answers Avg Quality 2/10

abstract class java

Comment

Abstract classes have some special features:

it's impossible to create an instance of an abstract class;
an abstract class can contain abstract methods that must be implemented in non-abstract subclasses;
it can contain fields and non-abstract methods (including static);
an abstract class can extend another class, including abstract;
it can contain a constructor.

Popularity 10/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Jan 30 2022

coder

0 Answers Avg Quality 2/10

abstract class java

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