java_base pers sample java base java block static block non-static block constructor block class load class load order data structure enum array collection List ArrayList LinkList(implements queue) Vector Map HashMap LinkedHashMap HastTable TreeMap Set HashSet TreeSet Queue java implement queue algorithm sort bubble sort choose sort quick sort keyword static this OOP (Object-oriented programming) Definition Abstraction (抽象) abstractSample Encapsulation (封装) private Inheritance (继承) inheritSample Polymorphism (多态) Principle SRP Single Responsibility Principle (单一职责原则) OCP Open－Close Principle (开放封闭原则) LSPt the Liskov Substitution Principle (替换原则) DIP the Dependency Inversion Principle (依赖原则) ISP the Interface Segregation Principle (接口分离原则) design pattern factory proxy singleton