Java优学网多态实现教程：轻松掌握方法重载与运行时多态，避免ClassCastException错误

public class Calculator {

// 重载示例：同名方法，参数不同
public int add(int a, int b) {
    return a + b;
}

public double add(double a, double b) {
    return a + b;
}

}

public class CoffeeMaker {

public void makeCoffee() {
    System.out.println("制作美式咖啡");
}

public void makeCoffee(boolean withMilk) {
    if(withMilk) {
        System.out.println("制作拿铁咖啡");
    } else {
        makeCoffee(); // 调用无参版本
    }
}

public void makeCoffee(boolean withMilk, int sugarLevel) {
    makeCoffee(withMilk);
    System.out.println("添加" + sugarLevel + "份糖");
}

}

Animal animal = new Dog(); Cat cat = (Cat) animal; // 运行时抛出ClassCastException