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());
	}
	
}