interview.java

// THE BAD
public class Lamp
{
	private int bulbAge;
	private String bulbType;
	private int shadeAge;

	public Lamp(int bulbAge, String bulbType, int shadeAge)
	{
		this.bulbAge = bulbAge;
		this.bulbType = bulbType;
		this.shadeAge = shadeAge;
	}

	public boolean needsMaintainance()
	{
		if(bulbType.equals("INCANDESCENT"))
			return bulbAge > 2;
		else if(bulbType.equals("HALOGEN"))
			return bulbAge > 5;

		return false;
	}
}


// THE BETTER
public class Lamp
{
	private Bulb bulb;
	private Shade shade;

	public Lamp(Bulb bulb, Shade shade)
	{
		this.bulb = bulb;
		this.shade = shade;
	}

	public boolean needsMaintainence()
	{
		return bulb.needsMaintainence();
	}
}

public abstract class Bulb
{
	private int age;

	public Bulb(int age)
	{
		this.age = age;
	}

	public boolean needsMaintainence()
	{
		return age > getMaxAge();
	}

	public abstract int getMaxAge();
}

public class IncandescentBulb extends Bulb
{
	public IncandescentBulb(int age)
	{
		super(age);
	}

	@Override
	public int getMaxAge()
	{
		return 2;
	}
}