1、 Person、Student类定义在JavaOop类里面，属于内部类， private String school是private 级别，Student类的s实例可以直接引用 School属性
2、将Person、Student类定义在JavaOop类外面，属于外部类，private String school是private 级别，Student类不可以直接引用 School属性，必须s.getSchool()来调用
package IMF;
public class JavaOop {
public static void main(String[] args) {
// TODO Auto-generated method stub
Student s = new Student();
s.setName("Spark");
s.setAge(6);
s.setSchool("Big Data");
System.out.println("Name:"+ s.getName() +" age" + s.getAge()+" school "+ s.getSchool());
s.sayHello();
Cat cat = new Cat();
cat.act();
Dream bigData = new BigData();
bigData.toDo();
}
}
class BigDat
