Java Program with Abstract classes

Last updated on February 5th, 2022 at 02:56 pm

Here is a Java program that helps you to understand the concepts of Abstract classes. Type, compile and run to understand how to use the concepts of Abstract class in a Java program.

Java program to understand the concepts of Abstract class

//a class can be declared abstract even if it does not have any abstract met

abstract class AbsClass
{
}

// must declare a class abstract if it has an abstract method

abstract class AbsClass2
{

/* must declare a method as abstract if
the method has no method body */

abstract void absMeth();
}

/*must declare a class as abstract if it does not override
the abstract method of its base class */

abstract class Child extends AbsClass2
{
int i,j;
Child(int i,int j)
{
this.i=i;
this.j=j;
}
}

//proper implementation of abstract methods
class Child2 extends Child
{
int k;
Child2(int i,int j,int k)
{super(i,j);
this.k=k;

}
void absMeth()
{System.out.println(“absMeth implemented in Child2”);
System.out.println(“I,J and K are:”+ i +” “+ j +” “+ k);
}
}

class AbsTest
{
public static void main(String args[])
{
Child2 c2=new Child2(10,12,14);
c2.absMeth();
}
}

Summary: Abstract class in Java

• A java class can be declared abstract even if it does not have any abstract method.
• Must declare a class abstract if it has an abstract method.
• Must declare a method as abstract if the method has no method body.
• you must declare a class as abstract if it does not override the abstract method of its base class.

Note: if you find any of the features mentioned above is not as per the current Java versions, then please mail us with suggestions for corrections and references.