Programmer Group

Today, after the sale, the consulting customer bought the certificate. There was a 400 error in https request. Let me help you get it. Seeing that the customer's code seems to be no problem, I tried it myself, and there really is an exception. Record to avoid being pitted later. Scenario: Two-way validation of SL, requests nee ...

Nio learning The article is a summary of my own study. If there is any misunderstanding, please leave a message. What is Nio? The full name of java.nio is java non-blocking IO (actually new io), which refers to the new api (New IO) provided in jdk1.4 and above for all primitive types (except boolean types). cache Supported data container, which ...

1. Edit profile file export JAVA_HOME=/usr/lib/jvm/jdk/ export HADOOP_INSTALL=/sur/local/hadoop export PATH=$PATH:$HADOOP_INSTALL/bin export PATH=$PATH:$HADOOP_INSTALL/sbin export HADOOP_MAPRED_HOME=$HADOOP_INSTALL export HADOOP_COMMON_HOMR=$HADOOP_INSTALL export HADOOP_HDFS_HOME=$HADOOP_INSTALL export YARN_HOME-$HADOOP_INSTAL ...

Java provides eight basic data types, each of which has its corresponding packaging type. The packaging class is an object-oriented class and a high-level data type. It can carry out some more complex operations. They are reference type instead of basic type. Corresponding relationship between basic type and packaging type Basic types ...

Baidu Encyclopedia Eclipse is open source code Based on Java Extensible development platform. In itself, it is just a framework and a set of services for building development environments through plug-in components. Fortunately, Eclipse comes with a standard set of plug-ins, including Java development tool(Java Development Kit ...

Excerpt from Professor Zhou Zhiming's "Deep Understanding of Java Virtual Machine: Advanced Features and Best Practices of JVM" 13.2.2 Thread Safety Implementation Method 1. Noun Interpretation Synchronization is to ensure that shared data is accessed by only one thread at the same time when the lock thread accesses shared data concur ...

HashMap for JDK Source Reading Introduction to HashMap HashMap class diagram Important Method of HashMap Method variables Construction method Essence method putVal resize Important method getNode putMapEntries clone HashMap changes HashMap Reading Feelings Explain Introduction to HashMap Implementation of Map inte ...

Article directory It's not hard to read the source code. software environment Membership variables: Construction method Core method get method remove method add method End It's not hard to read the source code. How to learn programming well? How to write high quality code? How to improve your programming ability quickl ...

Preface (1) Written earlier, since there is little experience in installing jdk+tomcat and other environments in linux or unix-like systems, we chose to install it in the docker container to prevent installation failure and failure to restore the system. (2) We need to download the docker image of the corresponding system, such as cento ...

Java multithreaded learning - java.util.concurrent (2) Semaphore/FutureTask/Exchanger 3. Semaphore  Let's start with a detailed introduction to this class in the JDK 1.5 API:"A counting semaphore. Conceptually, semaphores maintain a license set. If necessary, each acquire() is blocked before the license is available, and then the licen ...