sample5_7.java

封装

package qbe.cn;
public class Sample5_7
{
	public static void main(String[] args)
	{
		Car c=new Truck();
		System.out.println("访问的成员为："+c.aMember+"!");
	}    
}
class Car
{
	String aMember="我是汽车类的成员变量";
}
class Truck extends Car
{
	String aMember="我是卡车类的成员变量，汽车类也有";
}