sample5_4.java

封装

class Student
{
	int sage=21;
}
public class Sample5_4
{
	//声明final的引用并同时让其指向一个对象
	final Student d=new Student();
	public void setAge()
	{
		System.out.println("修改前的年龄为："+d.sage+"。");
		d.sage=25;
		System.out.println("修改后的年龄为："+d.sage+"。");
	}
	public static void main(String args[])
	{
		Sample2 s15=new Sample2();
		s15.setAge();
	}
}