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why we use abstract class in java

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Gabbar Virus answered on January 8, 2020 Popularity 3/10 Helpfulness 1/10

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Comment

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(instantiated->creating an object)

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.

abstract class Cars {
public abstract void carDetails();
}

class Maruti extends Cars {
public void carDetails() {
System.out.println("Maruti Details");
}
}

class Honda extends Cars {
public void carDetails() {
System.out.println("Honda Details");
}
}

class Scoda extends Cars {
public void carDetails() {
System.out.println("Scoda Details");
}
}

public class Main {
public static void main(String[] args) {
Cars obj = new Maruti();
obj.carDetails();
}
}

Popularity 3/10 Helpfulness 1/10 Language java

Source: Grepper

Tags: abstract-class java

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Contributed on Mar 15 2023

Gabbar Virus

0 Answers Avg Quality 2/10

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abstract class in java

Comments(2)

153

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

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 4/10 Language java

Source: Grepper

Tags: abstract-class abst

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Contributed on Dec 24 2023

sam9934

0 Answers Avg Quality 2/10

how to make abstract method in java

Comment

public abstract class Account {		//abstract class //perent class
    protected int accountNumber;
    protected Customer customerObj;
    protected double balance;
  	//constructor
  	public Account(int saccountNumber, Customer scustomerObj,double sbalance){
        accountNumber = saccountNumber;
        customerObj = scustomerObj;
        balance = sbalance;
    }
  	// abstract Function
    public abstract boolean withdraw(double amount); 
}   

public class SavingsAccount extends Account { // child class
    private double minimumBalance;
  	// constructor
    public SavingsAccount(int saccountNumber, Customer scustomerObj, double sbalance, double sminimumBalance) {
        super(saccountNumber, scustomerObj, sbalance);
        minimumBalance = sminimumBalance;
    }
	// Implementation of abstract function in child class
    public boolean withdraw(double amount) {
        if (balance() > minimumBalance && balance() - amount > minimumBalance) {
            super.setBalance(balance() - amount);
            return true;
        } else {
            return false;
        }
    }
}

Popularity 10/10 Helpfulness 3/10 Language java

Source: Grepper

Tags: abstract abstrac

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Contributed on Mar 30 2021

Vishal

0 Answers Avg Quality 2/10

What are abstract methods in java

Comment

An abstract method is the method which does’nt have any body. 
Abstract method is declared with
keyword abstract and semicolon in place of method body.

  public abstract void <method name>();
Ex : public abstract void getDetails();
It is the responsibility of subclass to provide implementation to 
abstract method defined in abstract class

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: abstract-methods abst

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Contributed on Nov 30 2020

Thankful Tuatara

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

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 6/10 Helpfulness 2/10 Language java

Source: chat.openai.com

Tags: abstract java

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Contributed on Jan 28 2024

Savindi Dadallage

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

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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

why we use abstract class in java

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