I. Foreword JDK (Java Development Kit) is the basis of all Java applications, which can be said that all Java applications are built on this. It is a set of APIs, or it is some Java Class. The latest version that has been officially released is JDK1.3. Considering that I am not familiar with Linux, and most of them are under the MS system, so I use Win2000. Second, download, installation download address is the official site of Java: java.sun.com, the country is everywhere. Under Windows, run the .exe file directly, install it to a directory, I use F: / JDK13 as an example here. Third, configure the "My Computer" (right-click) Advanced environment variable on "System Variable" ---> New "Enter: ClassPath, Variable Value Enter: f: / JDK13 / LIB / DT in the Variable Name: .Jar; f: /jdk13/lib/tools.jar; f: / jdk13 / bin; then determined; ok, configured, after restarting your computer, environment variables can be effective. Fourth, test (1) Write a simple Java program with a text editor: public class helloworld {public static void main (string args []) {system.out.println ("Hello World!");}} This example is The famous "Hello World", its function is to display "Hello World". Note: This file name must be "HelloWorld.java", the case is also distinguished. A careful friend will notice the same name after the public class. (2) Compile: Execute under the DOS command prompt: (note case) Javac HelloWorld.java will generate a HelloWorld.class file if it is normal. (3) Operation: Execute under the DOS command prompt: (note case) Java HelloWorld here has a Java beginner is very likely to encounter problems (not afraid of jokes, I am also) is input: java helloWorld.class is more .CLASS, must pay attention to, otherwise the following error will appear: Exception in thread "main" java.lang.noclassdeffounderror: helloWorld / Class (I guess, is it Java translation "." When it was changed to "/", Or the reason why the other I don't know) is good, running Java HelloWorld should have great "Hello World". In this step, you have successfully configured JDK, you can start long and pain (for me, I can't understand Java, you can use "pain" to describe, not understanding, unfamiliar java API ..., but don't worry, I will get started with everyone, slowly improve ...) Java procedure.
