Terminology

A method with a body is a concrete method. It can be called by the object.

A method with only the signature defined but no body. The method is called an abstract method. The class with a mix of concrete and abstract methods is called abstract class. We cannot create an object from an abstract class because of the missing body.

If you don't understand the above terminology, I encourage you to study a tutorial on abstract keyword in java$-$GeeksforGeeks.

Sample program

You are given $4$ Java source files: Car, MustangGT, Model$3,$ and TestTrack.

The Car class has a concrete pressGasPedal method and an abstract brake method.

Model $3$ is an electric car that can accelerate and brake faster than the conventional car Mustang GT with a combustion engine.

TestTrack is a class that takes the two cars for a test. Running the provided program will yield the following output.

Ford Mustang GT is going at $k\frac{m}{h}r.$

Ford Mustang GT is going at $129k\frac{m}{h}r.$

Ford Mustang GT is going at $172k\frac{m}{h}r.$

Ford Mustang GT is going at $95k\frac{m}{h}r.$

Tesla Model $3$ is going at $0k\frac{m}{h}r.$

Tesla Model $3$ is going at $157k\frac{m}{h}r.$