Myinterface

public class Computer {
private int size;
public Computer()
{
System.out.println("create a computer.");
}
public Computer(int size)
{
this();
this.size=size;
}

}

public interface Portable {
public boolean isPortable();
}

public class PortableComputer extends Computer implements Portable{
public PortableComputer()
{
super();
}
public PortableComputer(int mySize)
{
super(mySize);
}
public boolean isPortable()
{
return true;
}
}

public class TestPortable {
public static void main(String [] args)
{
PortableComputer computer =new PortableComputer();
System.out.println("computer is portable?"+ computer.isPortable());
}

}