1. cli (command line interface) and gui (graphic user interface) use javahome path, search classpath
2. java editions: j2ee(java 2 enterprise edition), j2se(java 2 standard edition), j2me(java 2 micro edition), after java5.0, rename to javaee, javase, javame
but j2me is not oridinally not used any more.
3. history: sun was takenover by Oracle. Oracle architect: java, oracle, linux, Oracle has a serie of software.
4.java features: mark: cross-platform based on JVM on different OSs, like, windows JVM, linux jvm, mac mvm.
5.jdk and jre: (jdk: compiler:javac.exe, packager:jar.exe, same with VS compiler and packager)java development kit, and java runtime environment(jre: java virtual machine and java class libraries.)
6. java6.0 platform
7. download jdk and and jre: goto www.oracle.com and java.sun.com to download java developer, and download jdk and jre, we use javaSE, standard edition.
oridinally, jre package size is smaller than jdk! sdk(software developer kit)
8. javafx: is a script programming language, like flex, but we do not need it.
9. use java cli. goto javac.exe, we have the DOS commands to operate files and other command line tools. type 'help' to get more info
10. configure environment variables. add javac.exe path to windows environment variables Path, call javac -version to see java version, we create a JAVA_HOME variable, then we replace relevant chars in java path with JAVA_HOME eg:
JAVA_HOME: E:JAVA PATH: %JAVA_HOME%BIN, but JAVA_HOME is a system. variable, use portable harddisk, create temporary environment variable:
but we can use DOS set command and set the variables, open cmd, if we just type set, we see all environment variables. type help set to get info about set command.
type set path, set our own PATH: set path=""", if we want to delete the variable, just type set path= ; now, we can set temporary path manually, just set path to our javac.exe physical path, we can use javac now! set path='our own local path';%path%, this means we just added a path, but not destroying the previous usables.
11. compile process: .java->(javac.exe compliled) .class-> result.
12.hello world: javac 123.java; , class Demo{ public static void main(String[] args) creates Demo.class, called by JVM, one main. ,then type java Demo to run our program!
12. classpath: we need to set a class path, we can execute any java files, jvm will first look into java classpath for executables, if classpath is set, jvm will look into classpath and current path for things. ';' will also add current dir to search scope: set classpath='optional' set classpath=.;c:myclasspath
Home Work:
to add!