What does abs mean in java

ABS stands for Abstract in Java and is used to define abstract classes and abstract methods. An abstract class defines a general structure but does not provide an implementation, and an abstract method declares a method but does not provide an implementation, which must be implemented in a subclass. Benefits include code reuse, extensibility, and interface contracts.

The meaning of ABS in Java

ABS is the abbreviation of abstract in Java, it is A keyword used to define abstract classes and abstract methods.

Abstract class

Abstract class is used to define the general structure and behavior of a class without providing a specific implementation. An abstract class contains at least one abstract method, that is, a method that has no implementation. An abstract class itself cannot be instantiated, but it can be inherited by subclasses, and subclasses must implement all abstract methods of their parent class.

Abstract method

An abstract method is a method declaration but does not provide any implementation. It must be implemented in subclasses. Abstract methods are declared with the keyword abstract, as shown below:

public abstract void doSomething();

Benefits of using abstract classes and abstract methods

Using abstract classes and abstract methods can bring the following benefits ：

• Code reuse: Abstract classes allow common features and behaviors to be defined as abstract methods, which can be reused in subclasses.
• Extensibility: Abstract classes allow new functionality to be added to a base class without modifying existing subclasses.
• Interface contract: Abstract methods can define interface contracts that require subclasses to implement specific methods to ensure that the subclass has the expected behavior.

Example

Consider an example where we define an abstract class Shape that contains an abstract method that calculates the area:

public abstract class Shape {
    public abstract double calculateArea();
}

Now, we can create subclasses of Shape, such as Circle and Rectangle, and implement the calculateArea() method of their parent classes:

public class Circle extends Shape {
    private double radius;

    @Override
    public double calculateArea() {
        return Math.PI * radius * radius;
    }
}

public class Rectangle extends Shape {
    private double width;
    private double height;

    @Override
    public double calculateArea() {
        return width * height;
    }
}

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