* Inheritance is used to reuse code and Java programming language allows you
* to either extend class or implements Interface. In this Program we have a
* Super Class Server and a Sub Class Tomcat, which is a Server.
* Tomcat inherit start() and stop() method of Server Super Class.
*
* @author Javin
*/
public class Inheritance{
public static void main(String args[]) {
//Super class reference variable can hold Sub Class instance
Server server = new Tomcat();
//we need to cast to get actual Server instance back in reference variable.
Tomcat tomcat = (Tomcat) server;
tomcat.start(); //starting Server
System.out.println( "Uptime of Server in nano: " + server.uptime());
tomcat.stop();
}
}
class Server{
private long uptime;
public void start(){
uptime = System.nanoTime();
}
public void stop(){
uptime = 0;
}
public long uptime(){
return uptime;
}
}
class Tomcat extends Server{
@Override
public void start(){
super.start();
//Tomcat Server specific task
System.out.println("Tomcat Server started");
}
@Override
public void stop(){
super.stop(); //you can call super class method using super keyword
System.out.println("Tomcat Server Stopped");
}
}
Output:
Tomcat Server started
Uptime of Server : 105898370823666
Tomcat Server Stopped
