六、面向对象之多态

// 多态
/*
* 如果方法签名不同，就是Overload
* 方法签名相同，并且返回值也相同，就是Override
* 标志重写父类方法*/
public class Object1 {
    public static void main(String[] args) {
        // 给一个有普通收入、工资收入和享受国务院特殊津贴的小伙伴算税:
        Income[] incomes = new Income[] {
                new Income(3000),
                new Salary(7500),
                new StateCouncilSpecialAllowance(15000)
        };
        System.out.println(totalTax(incomes));
    }
    public static double totalTax(Income... incomes) {
        double total = 0;
        for (Income income: incomes) {
            total = total + income.getTax();
        }
        return total;
    }
}
class Income {
//final class Income {   // final作用是：该类不能够被继承
    protected double income;
    //public final String name="小帅";   // final作用是：该字段初始化之后不能够被赋值
    public Income(double income) {
        this.income = income;
    }
    public double getTax() {
    //public final double getTax() {   // final作用是该父类方法不能被重写
        return income * 0.1; // 税率10%
    }
}
class Salary extends Income {
    public Salary(double income) {
        super(income);
    }
    @Override
    public double getTax() {
        if (income <= 5000) {
            return 0;
        }
        return (income - 5000) * 0.2;
    }
}
class StateCouncilSpecialAllowance extends Income {
    public StateCouncilSpecialAllowance(double income) {
        super(income);
    }
    @Override
    public double getTax() {
        return 0;
    }
}