Introduction to Java (10) - Encapsulation

Introduction to Java (10) - Encapsulation

Table of contents

Introduction to Java (10) - Encapsulation

encapsulation

benefit

step

     Notice

Sample code

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encapsulation

benefit

           - After encapsulation, you can only use the provided entrance when referencing, and the content inside cannot be changed, which has higher security
           - It is very convenient to use a simple operation entrance -
           A real "object" will be formed after encapsulation , a true independent body
           - the encapsulated program can be reused, has strong adaptability, and can be used in any situation

step

           - Therefore, to privatize attributes, use the private keyword to modify them. Private means private. All modified data can only be accessed in this class.
           - Provide simple entrances to allow external access. There are two forms of access: reading get, modifying set
           - set method naming rules: (example)
                public void setAge(int a){                     age=a;                 }            - get method naming rules: (example)                 public void getAge(){                     return age;                 }






          

     Notice

           - Getters and Setters can be generated through the source code
           - Getter and Setter methods do not have the static keyword
           - The calling method with static is: class name.Method name (actual parameters)
           - The calling method without static is: reference.Method name (actual parameters) ginseng)

Sample code

class User {
	
	private int age;
	
	static String name="张三";

	public void setAge(int age) {
		if(age<20 || age>40)
			System.out.println("抱歉您的年龄不适合我们的工作。非常抱歉！");
		else {
		    this.age = age;
		    System.out.println("您的年龄是"+this.age+"岁,很高兴您能加入我们的队伍。");
		}
	}

	public int getAge() {
		return age;
	}

}

public class Encapsulation{

	public static void main(String[] args) {
		
		User user = new User();
		
		//不能访问user.age，是因为age的属性私有化了。
		//System.out.println(user.age);
		
		System.out.println(User.name);//类名.方法名
		user.setAge(50);//引用.方法名
	}
}