What is Javajava is a development language (core features: cross-platform, object-oriented, name from the point of view here: what is the meaning of the 2 in the Java EE), for the developer, it basically equals the JDK. JDK Version Introduction Look here: Java has those version of developers generally through the IDE (Eclipse, NetBeans, JBuilder, etc.) writing, compiling Java code (in the era of No IDE, are written in a text editor, using Javac compilation), In this process, the JDK is used with the third-party jar package (the jar package is a set of compiled classes of the compressed package, you can use the decompression tool to extract the file structure).
Want to know what Java can do for you: Java is capable of what the specific diagram: where the JDK contains the JRE, in the JDK installation directory has a directory called the JRE, there are two folders Bin and Lib, here you can think of the bin is the JVM, LIB is the class library required for the JVM to work, and the JVM and Lib are called JRE. 11:16:301. What is Jdkjava Development Kit is a product for Java developers and is the core of the entire java. To install the JDK see here: How to install and configure the JDK
Includes: Java Runtime Environment JRE, Java Tools (JAVAC/JAVA/JDB, etc.) and Java base Class library (Java Api,rt.jar, etc.). 2. What is Jrejava Runtime environment
Is the set of environments required to run Java programs, including the JVM standard implementation and the Java Core Class library.
Unlike the familiar JDK, the JRE is a Java runtime environment, not a development environment, so there is no development tools (such as compilers and debuggers), but only for users of Java programs, only through it, Java developers can publish their own programs to the user's hands, Let the user use. Running Java programs generally requires the user's computer to install the JRE, no Jre,java programs can not run, and without Java programs, the JRE is useless. Includes: Virtual machine JVM, run class library (runtime class libraries) and launcher (Java Application Launcher). 3. What is Jvmjava Virtual machine
The Java virtual machine, which we often speak of, is the most central part of the entire Java implementation across platforms, capable of running applications written in the Java language.
All Java programs are first compiled into a. class file, and the JVM virtual machine can execute this compiled class file, which means that class does not directly correspond to the machine's operating system, but instead interacts with the operating system indirectly by the virtual machine, which interprets the program as the target code (different operating systems) to the local system.
The JVM masks information related to the operating system platform, allowing Java programs to run without modification on multiple platforms by generating only the target code that runs on the Java virtual machine.
Only the JVM cannot be executed as class, because the JVM needs to invoke the class library lib, the Lib class library in the JRE, which is required to interpret the class, and the individual JVM has no effect.
Java Basic Concepts (1) What is Java
