public class HelloWorld {

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

}

/** * 定义抽象类Income */
abstract class Income {

    // TODO    double income;

    public Income(double income) {
        this.income = income;
    }

    public abstract double getMoney();
}

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

    // TODO    public RoyaltyIncome(double income) {
        super(income);
    }

    public double getMoney() {
        return income * 0.2;
    }
}

class SalaryIncome extends Income {

    // TODO    public SalaryIncome(double income) {
        super(income);
    }

    public double getMoney() {
        return income * 0.2;
    }
}