封装性

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面向对象的三大特征：封装、继承、多态

封装的好处：隐藏实现的细节、更容易维护、更安全。

类就是一个封装体，封装了属性和方法。

匿名对象就是没有别名的对象。

public class Person {String name;int age;Person(){}Person(String name, int age){this.name = name;this.age = age;}public void thinking(){System.out.println(this.name+" thinking...");}public static void main(String[] args) {new Person("zhangsan", 18).thinking();}}

输出：

zhangsan thinking...

主方法

public static void main(String[] args)

public class Students {String name;String sid;char gender;//M:male F:femaleint age;String major;String mail;String qq;String address;static int num = 0;Students(){System.out.println("create a student...");num++;}Students(String sid, String name, char gender, int age, String major, String email, String qq, String address){this();this.sid = sid;this.name = name;this.gender = gender;this.age = age;this.major = major;this.mail = email;this.qq = qq;this.address = address;}public void goToClassroom() {System.out.println("go to classroom");}public void goToExam() {System.out.println("go to exam");}public static void study() {System.out.println("good good study day day up");}public static void main(String[] args) {Students s = new Students("s001", "meimei", 'F', 18, "Mec", "123", "133", "789");s.goToClassroom();s.goToExam();System.out.println("students num "+Students.num);}}

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