封装

public class Pet {
    private String name;
    private int age;
    //无参构造
    public void shout(){
        System.out.println("叫了一声");
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

/*
1.提高程序的安全性，保护数据
2.隐藏代码的实现细节
3.统一接口
4.系统可维护增加了
 */
public class Application {
    public static void main(String[] args) {
        Pet pet=new Pet();
        pet.setName("旺财");
        String name=pet.getName();
        System.out.println(name);
    }
}

继承