Programmer Group

  0x01: byte stream Byte stream base class 1. InputStream InputStream: the base class of byte input stream. The abstract class is a superclass representing all classes of byte input stream. Common methods: // Reads the next byte of data from the input stream abstract int read() // A certain number of bytes are read from the input st ...

1. Define your own database and data table 2. Access the defined data table through JDBC and insert 2 records. Requirements: 1. Submit SQL statements defined in database and data table; 2. Submit program implementation process; 3. Submit program running results. This is a small class assignment assigned by my teacher. What is JDBC JDBC(Jav ...

Today, I'm going to relearn enumeration types in Java. Why study again now? Because when I first started learning Java, I didn't pay much attention to enumeration. After work, I basically didn't use enumeration. As a result, I don't quite understand the data type of enumeration. Sometimes when I see the enumeration types and related operations ...

catalogue RedisTemplate switch Jedis implementation Switch the underlying Jedis API operation Redis RedisTemplate switch Jedis implementation 1. Spring Boot is Lettuce and Jedis The client library provides basic automatic configuration. By default, it is used Lettuce As a client, if you want to switch the Jedis client, there are two steps: ...

In the process of selling tickets, there are thread safety problems, including duplicate tickets and wrong tickets. Why is this problem? When a thread has not completed the ticket selling operation during the operation of ticket selling, and other threads also participate in the operation of ticket selling, thread safety problems will occur ...

1. Three ways to obtain class objects hello h = new hello(); //1. Obtain class objects through instance objects Class class1 = h.getClass(); System.out.println(class1); System.out.println(class1.hashCode()); //2. Get class object by object name Class class2 = hello.class; System.out.println(class2); System.out.println(class2.hashCode ...

1. Overview of arrays and sets Collections and arrays are structures that store multiple data, referred to as Java containers for short. Note: the storage at this time mainly refers to the storage at the memory level, and does not involve persistent storage (. TXT,. JPG,. Avi, in the database). Characteristics of array storage ...

1. What is object-oriented? stay Java In order to obtain objects, you must first design classes. Class (design drawing): Description of common characteristics of objects; Object: A concrete instance of what really exists The basic format of a class: public class Class name{ 1.Member variables (representing attributes) 2.Member method (repre ...

Content index Class loader Class loading system Class loading Dynamic class loading Dynamic class overloading Custom class overload Class load / reload example Java allows you to dynamically load and reload classes at run time, but this function is not as simple and direct as people want. This article will explain how to load and overload cl ...

Surrounded areaTitle Description: give you a matrix board of m x n, which consists of several characters' X 'and' O ', find all areas surrounded by' X ', and fill all' O 'in these areas with' X '.See LeetCode's official website for an example.Source: LeetCode Link: https://leetcode-cn.com/probl... The copyright belongs to Lingkou network. For ...