Java

Two days ago, because of the architectural design of the system, to access the hive database directly through Java, for my Java and Hadoop platform Novice, it is really difficult, but fortunately, it is done. The feeling is not very troublesome.

201621123021 Java programming Fifth week of study summary 1. Study summary of this week 1.1 write down the key points of knowledge you think are important in this week's study interface, comparator interface, comparable interface, HAS-A

The Excel data is imported into the database because it is used in the project. Share it here.The POI method used here supports two formats (XLS,XLSX)Package Com.entity;import Java.io.file;import Java.io.fileinputstream;import

Java from getting started to mastering indexingOriginal link: http://dashidan.com/article/java/index.htmlIn early 20th century, Italian economist Pareto found an interesting rule: in any group of things, the most important is only a small part,

using the class's static fields and constructors, we can track the number of objects created by a class. Write a class that can query it at any time "How many objects have you created?" ”。idea: Because the static initialization block runs only once,

Public void ImportFile (Multipartfile uploadfile) throws IOException {String fileName = Uploadfile.getoriginalfilename ();String fileType = "";if (Filename.lastindexof (".")! =-1&& Filename.lastindexof (".") + 1 FileType = filename.substring

1. The concept of the Java reflection mechanism2. How to instantiate a class objectClass.forName (package name. class name);Object. GetClass ();Classes. class;============================ Code ===================================Package

ASCII code for letters and numbers The most widely used character set and its encoding in the current computer are ASCII codes developed by the United States National Standards Agency (ANSI) (American Standard Code for information interchange, US

Abstract class:Scene:Multiple classes inherit a class, and when we need to call a method, because the method body is different, it has an object feature. This time the base class creates an abstract method that takes the place of a subclass that

Java fragmented knowledge point one: Array 1. Efficiency comparison of several methods of array copyingEfficiency: system.arraycopy > Clone > Arrays.copyof > For loopFor loopFor loop, the least efficient.System.arrycopy ()System.arraycopy () can be

design of Java genericsIntroductiongenerics areA very important point of knowledge in Java, generics are widely used in the Java Collection Class framework. In this article we will look at the Java generics design from scratch, which will involve

Look at the previous processing in the project is directly using the Java IO Class library to read the CSV file, the actual processing found that the CSV file itself contains a variety of special characters processing information.The most common

1. File UploadByte[] Type in Pojo, which corresponds to the BLOB type in the database.Main code:FileInputStream FIS = null;FIS = new FileInputStream (new File (FilePath));byte[] Inputbyte = Input2byte (FIS);Filebean.setcontent (Inputbyte);/***

Reprinted from: http://www.cnblogs.com/lwbqqyumidi/p/3821389.htmlWindstepThis article goes on to summarize the thread-safety issues in Java multithreading with two articles in front of multiple threads.I. A typical Java thread safety example 1

The class initialization phase is the last step in the loading process, where the variable has already assigned the initial value of the system requirement, and during the initialization phase, the class variables and other resources are initialized

One, the visibility of the volatile keywordTo understand the volatile keyword, first understand the Java memory model, the Java memory model is abstracted as follows:Can be seen:① each thread has its own local memory space-the line stacks space???

Struts201 --- environment match, struts201 --- match Development Tool: Eclipse Struts version: 2.3.24   Recently, I have been studying the SSH framework. SSH is an integrated framework of struts + spring + hibernate and is a popular open-source

Based on asp, jsp, java, vb and other computer science Graduation Design Questions Daquan, jspvb I found a lot and found it was a part of it. Many of them were incomplete. Then I sorted them through the network. If I was interested, I could leave

Summary of Java back-end development interview questions of major companies, and java back-end interview questions ThreadLocal (thread variable copy)Synchronized implements Memory sharing. ThreadLocal maintains a local variable for each thread.It

Exams + job fairs, Job Fairs Today, get up and go to the library for level 2 .. I haven't looked at C for a long time, and my mind is full of Java... I reported how good Java is! After the examination, I ran to the courier store to take the stupid