In Java, Abstract classes can have constructors even when they are only called from their concrete subclasses.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.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();
}
}// create an abstract class
abstract class Language {
// fields and methods
}
...
// try to create an object Language
// throws an error
Language obj = new Language();abstract void display();/*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();
}
}