class Base {
    public void show() {
        System.out.println("Base class show() method called");
    }
}

class Derived extends Base {
    public void show() {
        System.out.println("Derived class show () method called");
    }
}

public class Main {
public static void main(String[] args) {
    Base b = new Derived();//why is java allowing me to create an object of child class
    b.show();              //how can the Base class hold and use the reference of child
    }                              
}

如果我在子类中创建一个新方法会怎么样？？父类是否仍然能够访问新方法？？

class Derived extends Base {
    public void show() {
        System.out.println("Derived class show () method called");
    }
    public void poo() {
        System.out.println("take a poo");
    }
}

public class Main {
public static void main(String[] args) {
    Base b = new Derived();
    b.show();   
        b.poo(); 
    }                              
}

为什么java允许我将一个子对象的引用赋值给基类，而不抛出任何警告或错误？