public class Main {

	public static void main(String[] args) {
		// TODO: 给一个有工资收入和稿费收入的小伙伴算税:
		Income[] incomes = new Income[] { new Income(3000), new SalaryIncome(7500), new RoyaltyIncome(12000) };
		double total = 0;
		// TODO:
		for (Income income: incomes){
			total = total + income.getTax();
		}
		System.out.println(total);
	}

}

/**
 * 稿费收入税率是20%
 */
public class RoyaltyIncome extends Income {

	// TODO
	public RoyaltyIncome(double income) {
		super(income);
	}
	@Override
	public double getTax() {
		return income * 0.2; // 税率20%
	}

}