面向对象的特征：继承，封装和多态
java 当中只支持单继承，不允许多继承
class Person
{
String name;
int age;
void eat()
{
System.out.println("吃饭");
}
void introduce()
{
System.out.println(“我的名字是"+name+",我的年龄是"+age);
}
}
继承的关键字：extends
class Student extends Person
{
int grade;
void study()
{
System.out.println("学习");
}
}
class Test
{
public static void main(String args[])
{
Student student=new Student();
student.name="zhangsan";
student.age=18;
student.eat();
student.introduce();
}
}