??????????????锟�?Java??????????????????
????1?? ???
????2?? ??????写??????
????3?? ??????????????????
??????????????
package test.xing;
class Father{
protected int age;
public Father(){
age = 40;
}
void eat(){
System.out.println("????????");
}
}
class Child extends Father{
protected int age;
public Child(){
age = 18;
}
void eat(){
System.out.println("????????");
}
void play(){
System.out.println("???????CS");
}
}
public class TestPolymorphic {
public static void main(String[] args) {
Father c = new Child();
c.eat();
//c.play();
System.out.println("????"+c.age );
}
}
?????????????

?????????????????Java???????????????????????c.eat()?????????????????eat????c.age????????????age????c.play()???????????
?????????JVM???????????????????
?????????Father c = new Child()??浠�????
??????浠�????????new Child()??????蟹??????????
????????????Child???????????????JVM???????????Child??????class????????JVM?校????JVM????class????械????????????????class?????????????????
????????????????????????JVM???胁???????????????????????????????JVM??娣�??
??????????class??????????????????????????????????
????1?? ??????
????2?? ????????????????
????3?? ??????
????4?? ???????
????5?? ?????????
????6?? ??????????????
??????些?????????????????????????JVM?????榧�?纭�???????Java????????????????懈????????谩?
???????JVM?????????????????????????????????????????????????????java?????????????
???????????邪??????????????????????????????????????????????些??????????????????????????????????????????????????????
???????????些????????????????????????????????涓�???????????????????????????????????????Object????
???????????些?????胁???????蟹??????????蟹????????校?
???????????械???些??????????JVM?斜?????????????????澹�????????????澹�??????????????????????????4?????位?????????????????????????谢??懈??????????????????????????????????位?谩?
???????????????????????婊�????????

?????????????????????胁?????????????????????????????????????????????????????Child?????????????
??????????????校?????????????Object???????????????些???????toString??????equals??????Object?谢????????????????写??
????????????胁??????????Parent??????????????????eat??
???????????????????????谩?
???????????????????????Child??????????????Parent???械???????????????????????eat???????????????????????????????????????????eat?????????????渭??????????械????????????????Parent.eat???????????婊�?????Child.eat????????????????械?位??????????????????Child????????????????Child.eat??Parent????????????????Parent.eat????????????????????Parent.eat?????????
??????????????????????Parent??Child????????校????eat??????????械???????????????????????位?谩??????????????eat??????????????eat??????????????????eat??????????????械?位???
???????????????????????????????校???????????????????????械??????????写????????????懈????????????
??????????????????????????????卸?????

?????????????????????Father????????????????????????械?Child????????
??????????????????Father c????澹�???????c???????????????????????械?Child??????????????????????????????????械?Child??????????????????????????婊�?????Father???????c
??????????????c????void????????????????????????????????????????????????????char * p???p?????????????????????妫�????int *p??p??????????????????????妾�
??????????????????????????????????????????????????????????蟹?????????????char *?????????p???????????????????????????????????小??????????????????????????
??????????java????????Father?????????c?????????????妫�??婕�????????????????小??
?????????Father?????????小??????校???Child???????????校??????????????锟�???
???????????c??????Child????????????????Father????????????????????械??????????c???????????Child???械?age?????????????Father???age?????????40
????????????????????????????

???????????Parent???????????校?Child????????4?校?c????????Child???????????????????????????Child?????????????????c?????Father?????危????c????????Child?????????3?械????????????
????????????????????????纬?????校???????写??????????????????????????Child???????????????????Child.eat????????????????Parent.eat??????????????????????????c?????????Child.eat???????????????????????????锟�?c????邪?????????????eat???????
???????????????????????
?????????????????淇碕VM??????????貌??????????????????????谢谢??