实际应用中表现: public class A { public String name=""; protected String aName="; private String myName="A"; public void print(){
System.o.println("I am a A"); }}public class B extends A { public void print(){ System.out.println("I am a B"); } public void pp(A a){ a.print(); }}1. 继承 B继承了A 2. 多态 A a=new A(); A b=new B();
public class A { public String name=""; protected String aName="; private String myName="A";
public void print(){
System.o.println("I am a A");
}}public class B extends A { public void print(){ System.out.println("I am a B");
} public void pp(A a){ a.print();
}}1. 继承 B继承了A
2. 多态 A a=new A();
A b=new B();
b.pp(a);
b.pp(b);3. 封装
A 的属性有:name aName myName B 的属性有:name aName
...
b.pp(b); =〉 ((B)b).pp(b);