Java-examples

Phone.java

public class Phone {
	private double credit;
	Phone(double inCredit) { 
		credit = inCredit;	
	}
	public double getCredit() {	return credit;	}
	public void setCredit(double credit) {
		this.credit = credit;
	}
	public void call(double minute) {
		credit -= callCost(minute);
	}
	protected double callCost(double minute) {
		return 0;
	}
}

PrepaidPhone.java

public class PrepaidPhone extends Phone {

	PrepaidPhone(double inCredit) {
		super(inCredit);
	}

	protected double callCost(double minute) {
		if(minute <= 1)
			return 1;
		else
			return 1 + (minute - 1) * 0.5;
	}
}

PostpaidPhone.java

public class PostpaidPhone extends Phone {

	PostpaidPhone(double inCredit) {
		super(inCredit);
	}

	public double callCost(double minute) {
		return minute * 0.25;
	}
}