Java访问修饰符原理及代码解析

一、概述

访问等级比较：public > protected > default > private

无论是方法还是成员变量，这四种访问权限修饰符作用都一样

public:不管包外包内，所有类（子类+非子类）均可使用 protected 包内：所有类可使用 包外：子类可使用，非子类不可使用 default 包内：所有类可使用 包外：所有类不可使用 private：仅本类可使用

二、示例代码

Test包内的父类Permission

public class Permission { private int privateValue = 1; public int publicValue = 1; protected int protectedValue = 1; int defaultValue = 1; void defaultFunc(){ System.out.println('This is a default function'); } public void publicFunc(){ System.out.println('This is a public function'); } protected void protectedFunc() { System.out.println('This is a protected function'); } private void privateFunc(){ System.out.println('This is a private function'); }}

Test包内的子类SubPermission

public class SubPermission extends Permission{ public void permissionTest(){ // public, protected, default function and variable can be used System.out.println('this is a default value:' + this.defaultValue); System.out.println('this is a public value:' + this.publicValue); System.out.println('this is a protected value:' + this.protectedValue); this.publicFunc(); this.protectedFunc(); this.defaultFunc(); }}

Test包外的子类

import base.Test.Permission;public class Demo extends Permission { public static void main(String[] args) { // if is not a subclass, only public function and variable can be used Permission obj = new Permission(); obj.publicFunc(); System.out.println('this is a public value:' + obj.publicValue); // if is a subclass, public and protected function and variable can ba used Demo demo = new Demo(); demo.publicFunc(); demo.protectedFunc(); System.out.println('this is a public value:' + demo.publicValue); System.out.println('this is a protected value:' + demo.protectedValue); }}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持好吧啦网。