Common terminology and differences in Java

In Java there are always a few terms, usually said more, but still let a person a little touch the mind, today to analyze their differences:

L jdk:java Development Toolkit, yes  java  ( Sdk). Here java ( jre , java< Span style= "font-family: Arial" > tool ( javac/java/jdb Java basic class library Java API includes rt.jar ).

Did you see that? The JDK contains the JRE and Java APIs! So, theJDK can be said to be all-encompassing .

L jre:java runtime Environment, is run based on java language program is indispensable to the operating environment. jre java virtual machine Span style= "font-family: Arial" > ( JVM runtime class libraries Span style= "font-family:arial" >java Application Launcher These are run java The necessary components of the program.

     This means jre contains JVM and it's just a running environment (actually mostly jvm< Span style= "font-family: Arial" > run on it, java programs are all in the JVM Java program can be run, there is no development tools (compiler, debugger, etc.)

L jvm:java virtual Machine is what we always say java virtual machine, which is the entire java Implements the most central part of cross-platform, all java The program is first compiled to .class class

    Note: only Jvm class Because the class Jvm need to invoke to interpret the required class library lib jre contains lib Class library. JVM screen specific operation of the system platform-related information, so that the Java The program only needs to be generated in java virtual machine on transport line of the target code (bytecode), you can run on a variety of platforms without modification

L J2SE:java 2 standard Edition is the Java Standards Edition for standard application development ; is actually an official standard, products that meet this standard are called "implementations". Since j2se is a standard version, only the JDK can be implemented.

L J2ME:java 2 micro Edition is a miniature version of java , often used in mobile phone development ; is actually an official standard, the product conforms to this standard is called "realizes". because of the embedded development, so J2ME will have other standards, and meet this standard is the implementation of J2ME, support J2ME .

L-ee:Java 2 Enterprise Edition is A business version of Java for enterprise-class application services development ; is actually an official standard, the product conforms to this standard is called "realizes". Because it is used for enterprise-level development, the Java EE will have a more powerful standard than the JDK , and to meet this standard is to implement the Java EE, support java ee, like jboss,weblogic.

L Java api:application Programming Interface, the application programming interface is a pre-defined function that provides applications and developers to access a set of routines based on a software or hardware without having to access the source code, or understand the details of the internal working mechanism

RunJavaprogram,Virtual MachinesLoader program'sClassfileis used byJava API Classfile. All the loadedclassfile(both from the application and from theJava APIextracted from the)and all the dynamic libraries that have been loaded(include local methods)together to form aJavaThe entire program that runs on the virtual machine. In a platform to supportJavaprogram, you must explicitly implement it on this particular platformAPIthe function. To access local resources on the host,Java APIThe local method was called. BecauseJava API classthe file called the local method,JavaThe program will not need to call them again. By this method,Java API classThe file is the underlyingHostprovides platform-agnostic, standard-interfaceJavaprogram. TheJavaprogram, regardless of the internal platform,Java APIwill have the same performance and predictable behavior. It is precisely because on each particular host platform that you explicitly implement theJavaVirtual Machinesand theJava API,

Common terminology and differences in Java