JAVA语法：子类成员覆盖父类成员时的现象

1.重温JAVA语法：如父类Father与子类Son：

class Son extends Father{
public String name = "son";

public void say(){
System.out.println("i am " + this.name);
}

public static void main(String[] args){
Father f = new Father();
System.out.println("Father f = new Father() : f.name => " + f.name);
System.out.print("Father f = new Father() : f.say() => ");
f.say();

Father fa = new Son();
System.out.println("Father fa = new Son() : fa.name => " + fa.name);
System.out.print("Father fa = new Son() : fa.say() => ");
fa.say();

Son son = new Son();
System.out.println("Son son = new Son() : son.name => " + son.name);
System.out.print("Son son = new Son() : son.say() => ");
son.say();
}
}

输出结果为：

Father f = new Father() : f.name => father
Father f = new Father() : f.say() => i am father
Father fa = new Son() : fa.name => father
Father fa = new Son() : fa.say() => i am son
Son son = new Son() : son.name => son
Son son = new Son() : son.say() => i am son

由此可见，当子类与父类具有同样的成员属性（public）与方法（public）时，父类变量引用子类对象时，

a.父类变量调用成员属性时，子类成员属性不会覆盖父类成员属性，不具动态性；

b.父类变量调用方法时，子类方法将会覆盖父类方法，具有动态性。

为何会如此，目前不明白，还请知道的朋友赐教。