Create a vehicle class

Modify your Car Class application. Now you will create an abstract class for a Vehicle. The Vehicle can run, stop and accelerate. However the abstract class can not fly like a plane or float like a boat. Nor can it haul 10 tons of gravel like the dump truck that just dinged my windshield. Specific implementations are created by inheriting your abstract class.

How to inherit an abstract class

To inherit your abstract class and all it's methods, etc... use the keyword extends. Then create a Plane class, a Boat class and a Car class. Each subclass you create will inherit from the Vehicle class. Any method the vehicle has will be available to the Plane, Boat or Car. Methods you add to the Plane, Boat or Car are specific to that type of Vehicle. For example, you may have a method to make the plane fly which won't be available to the car or boat class (until next century).

Preventing Inheritance

You can make your Plane, Boat and Car implementations final by using the keyword final after the modifier public in the class definition. Final classes can't be inherited. This isn't common but you may sometimes see people do this. Also, you can prevent a specific method from being overridden in the same way.

An Abstract class

can not be used to create an object; it must be inherited
can contain fields, constructors and methods like any other class
can optionally contain abstract methods

Abstract Methods

abstract methods do not have a body (example shown below)
Abstract methods, if any, must be overridden by the subclass. This is also illustrated below.

Example Abstract Class

public abstract class Message { private String sender; private String receiver; public String getSender() { return sender; } public void setSender(String sender) { this.sender = sender; } public String getReceiver() { return receiver; } public void setReceiver(String receiver) { this.receiver = receiver; } abstract String SubmitContent(); //an abstract method }

Example subclass for email message

public class EmailMessage extends Message{ private String messageBody; public String getMessageBody() { return messageBody; } public void setMessageBody(String messageBody) { this.messageBody = messageBody; } @Override String SubmitContent() { String status = ""; status = SendEmail(getSender(),getReceiver(), getMessageBody()); return status; } private String SendEmail(String sender, String receiver, String messageBody2) { // code to send the email and set return status goes here return "Message Sent"; } }

Create a vehicle class