多态的2个缺陷

最近在研读<<Thinking in Java>>......

多态的2个缺陷，其一：对私有方法的“覆盖”。只有非private方法才可以覆盖，因为private方法会被自动默认为是final方法。

public class Father {

	private void f() {
		System.out.println("Father's f()");
	}

	public void p() {
		System.out.println("Father's p()");
	}

	public static void main(String[] args) {
		Father f = new Sun();
		f.f();//Father's f()
		f.p();//Sun's p()
	}

}

class Sun extends Father {

	public void f() {
		System.out.println("Sun's f()");
	}

	public void p() {
		System.out.println("Sun's p()");
	}

}

其二：域与静态方法不具多态性。因为域是分配有存储空间的，父类与子类的域名虽然相同，但其存储空间不同。静态方法也同样道理。

public class FieldAccess {

	public static void main(String[] args) {
		Super sup = new Sub();
		System.out.println(sup.field);//0
		System.out.println(sup.getField());//1
		System.out.println(sup.dynamicGet());//Sub's dynamicGet
		System.out.println(sup.staticGet());//Super's staticGet

		Sub sub = new Sub();
		System.out.println(sub.field);//1
		System.out.println(sub.getField());//1
		System.out.println(sub.getSuperField());//0

	}

}

class Super {

	public int field = 0;

	public int getField() {
		return field;
	}

	public String dynamicGet() {
		return "Super's dynamicGet";
	}

	public static String staticGet() {
		return "Super's staticGet";
	}
}

class Sub extends Super {

	public int field = 1;

	public int getField() {
		return field;
	}

	public int getSuperField() {
		return super.field;
	}

	public String dynamicGet() {
		return "Sub's dynamicGet";
	}

	public static String staticGet() {
		return "Sub's staticGet";
	}
}