Java learning-Getting Started literacy articles

Overview

The recent few days have started to enter Java learning, exposed to a lot of concepts that are not very well understood, such as JDK, JRE, JVM, GC and so on, put here for the next literacy.

Java

Java is an object-oriented programming language and Java the general name of the platform, i.e. Java include Java Language and Java platform.

Javalanguage

Java language is the same as what we've been exposed to. C # , C + + language is the object-oriented language, with the basic characteristics of object-oriented language , Java language also has its own characteristics. For example, some features of garbage collection are added.

The same time the Java language programming style with C #,C + + is also very similar, all java language is easier to learn.

Jdk

JDK is an abbreviation for the English Java Development Kit, which is Java a software development kit. His feature is that every program starts with a command line call. In addition to the JDK and Java IDE, theJava IDE contains Eclipse, MyEclipse, IntelliJ, JBuilder, Jdeveloper, Netbeans, JCreator, etc.

Jre

JRE is the English abbreviation for Java runtimeenvironment. Refers to the Java execution Environment,the set of environments that theJava program executes. The class library that contains the JVM and Java.

Jvm

JVM commonly known as virtual machines. is the abbreviation of Javavirtual machine, virtual machines It is a specification for computer equipment, that is, the virtual machine is an imaginary machine, with its own finished hardware architecture such as processor, stack, register, etc., also has a corresponding instruction system, On the actual computer is the software to simulate the implementation of computer hardware. So now I understand that for a virtual machine as a software, this software is like a computer, it implements the computer equipment specifications. Enables Java programs to execute on top.

JVM is a Java One of the most attractive features of the Java language is the independence of the platform.

The use of Java virtual machines is the key to achieving this feature. General high-level languages are assumed to be executed on different platforms, at least to be compiled into different target codes. And after the Java language virtual machine is introduced. The Java language does not need to be compiled again when it executes on different platforms. The Java language usage mode Java Virtual machine masks information related to the detailed platform, allowing the Java language compiler to generate only the object code (bytecode) executed on the Java Virtual machine, which can be executed without modification on a variety of platforms.

Gc

GC is the garbage collection mechanism, is garbagecollection English abbreviation, GC is a JVM provides the ability to release memory for objects that are no longer used, regardless of the referenced object. It is important to note that garbage collection is a collection of memory space that is not occupied by objects that are not referenced by any reference, not the objects themselves that are no longer used.

JavaPlatform

Java The platform consists of Java virtual machines (javavirtual machine) and Java application programming interfaces (Applicationprogramminginterface, short API). The Java application programming interface provides a standard interface that is independent of the operating system.

Java platform consists of three systems J2SE that is javase (JAVA2 Platform Standardedition,java Platform Standard Edition). java ee (Java2 platform,enterprise Edition. Java Platform Enterprise Edition), j2me is Javame (Java 2 Platform Micro Edition,java Platform mini version).

All three of these are Java platforms. is The standard for Java development. Just different standard application range is not the same,j2se for the standard version,java EE for Enterprise Edition,j2me for miniature version

Summarize

Some of these things are encountered in learning. Some of them are often heard, through this article. I hope I can have a perceptual understanding of this knowledge. The principle of these aspects has not been carried out in-depth research, mainly is to solve the "fear not to know" problem.

Java learning-Getting Started literacy articles