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Explain Java reflection mechanism in detail Experience the benefits of reflection through cases case US group take away - > payment - either paid with WeChat or paid by Alipay. //Interface maker: meituan takeout public interface Mtwm { //Online payment function: void payOnline(); } public class WeChat implements Mtwm{ @ ...

Basic implementation of HashMap (before JDK 8) HashMap usually uses a pointer array (assumed to be table []) to disperse all keys. When a key is added, it will calculate the subscript i of the array through the key through the Hash algorithm, and then insert this into table[i]. If two different keys are counted in the same I, it is called conf ...

preface sleep method and wait method are two very confusing concepts, which are often asked. This paper introduces the characteristics of the two methods and the differences between the two methods, which is helpful for us to understand and distinguish. 1, sleep() The sleep() method is a method in the Thread class. Calling this metho ...

Basic concepts of operating system (Master) example: The program keeps outputting a greeting on the screen(Like "hello") "At the same time, when I input fixed input through the keyboard, the program stops outputting greetings to the screen(For example, input gun) Single thread package com.cskaoyan._01introduction; import java.ut ...

Common API 1. Scanner class 1.1 what is the Scanner class A simple text scanner that can parse basic types and strings. For example, the following code enables the user to download from system Read a number in: Scanner sc = new Scanner(System.in); int i = sc.nextInt(); Remarks: system In system input refers to entering data through the ke ...

1. Spring framework overview 1. Spring is a lightweight open source Java EE framework 2. Spring can solve the complexity of enterprise application development 3. Spring has two core parts: IOC and Aop (1) IOC: inversion of control, leaving the process of creating objects to Spring for management (2) Aop: aspect oriented, without modifying ...

This chapter mainly clarifies multithreading Processes and threads Process is the unit of system resource allocation, and thread is the unit of CPU scheduling and execution There are three ways to create threads Inherit Thread class (not recommended to avoid the limitation of OOP single inheritance) The custom Thread class inherits t ...

Object Object class is the parent class of all classes, that is, all classes in Java inherit object by default, and subclasses can use all methods of object. public class Test { } amount to public class Test extends Object { } The Object class is the root of the class hierarchy. The Object class is the only class in Java that does ...

Chapter VI: exception handling one 1. Overview of anomalies one 1.1 introduction of abnormality one 1.2 concept of abnormality two 2. Anomaly classification three 2.1 abnormal system three 2.2 Throwable......................................................................................................................... 3 2.3 error fou ...

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