Abstract Classes Are Required To Contain Abstract Methods

It can have abstract and non abstract methods method with the body.

Abstract classes are required to contain abstract methods. Abstract classes may not be instantiated and require subclasses to provide implementations for the abstract methods. An abstract class cannot be instantiated. Abstract classes cannot be instantiated but they can be subclassed. Unlike c in java a separate keyword abstract is used to make a class abstract.

Abstract classes in java in c if a class has at least one pure virtual function then the class becomes abstract. No you can declare a class abstract without having any abstract methods. A class which is declared with the abstract keyword is known as an abstract class in java. It is not possible to modify an abstract class with the sealed modifier because the two modifiers have opposite meanings.

An abstract method is a method that is declared without an implementation without braces and followed by a semicolon like this. It may not make any sense conceptually for an instance of that class to exist or you may want to ensure that only subclasses of that class can be instantiated for whatever reason. Abstract classes are classes that contain one or more abstract methods. The sealed modifier prevents a class from being inherited and the abstract modifier requires a class to be inherited.

Before learning the java abstract class lets understand the abstraction in java first. Lets look at an example of an abstract class and an abstract method.