1.将方法调用同方法主体关联起来被称为java
2.编译期绑定(静态)是在程序编译阶段就肯定了引用对象的类型spa
3.运行期绑定(动态绑定)是指在执行期间判断所引用对象的实际类型,根据其实际的类型调用其相应的方法对象
4.除了static方法和final方法(private方法属于final方法),其余全部方法都是后期绑定,Java中全部的方法都是经过动态绑定来实现多态blog
5.访问某个域的行为不具备多态性继承
package polymorphism; class SuperField { public int field = 1; public int getField() { return field; } } class SubField extends SuperField { public int field = 2; public int getField() { return field; } public int getSuperField() { return super.field; } } public class FieldPolymorphism { public static void main(String[] args) { SuperField sup = new SubField(); System.out.println("sup.field = " + sup.field + ", sup.getField() = " + sup.getField()); SubField sub = new SubField(); System.out.println("sub.field = " + sub.field + ", sub.getField() = " + sub.getField() + ", sub.getSuperField() = " + sub.getSuperField()); } }
输出结果:get
sup.field = 1, sup.getField() = 2
sub.field = 2, sub.getField() = 2, sub.getSuperField() = 1编译器
当SubField对象转型为Super引用时,任何域访问操做都将由编译器解析,所以不是多态的,SubField实际包含两个称为field的域:本身的和从SuperField处继承来的编译
一般将域设置成private,不能直接访问,也不能被继承,经过调用方法来访问 class
6.访问某个静态方法不具备多态性,不与单个对象相关联引用
package polymorphism; class Super { public static String staticMethod() { return "Super staticMethod()"; } } class Sub extends Super { public static String staticMethod() { return "Sub staticMethod()"; } } public class StaticPolymorphism { public static void main(String[] args) { Super sup = new Sub(); System.out.println(sup.staticMethod()); System.out.println(Sub.staticMethod()); } }
输出结果:
Super staticMethod()Sub staticMethod()