5.1inherite.java

JAVA程序设计的源代码

class superclass    //定义父类
{
String s = "father";
}

class subclass extends superclass    //定义子类
{
String s = "son";
}

public class Inherite    //定义测试类
{
public static void main(String arg[])
{
superclass sp,sp_ref;
subclass sb,sb_ref;
sp=new superclass();    
sb=new subclass();
sp_ref=sb;    //父类引用可以指向子类对象
sb_ref=(subclass)sp_ref;    //父类引用转换成子类引用

System.out.println(sp.s);
System.out.println(sp_ref.s);
System.out.println(sb.s);
System.out.println(sb_ref.s);
}
}