Java 学习笔记Hello World

1.下载 java JDK

http://www.oracle.com/technetwork/java/javase/downloads/index.html

2.安装 JDK

3.打开命令行

输入 java

按下 Enter

你会看到

Usage: java [-options] class [args...]

(to execute a class)

or java [-options] -jar jarfile [args...]

(to execute a jar file)

where options include:

-d32 use a 32-bit data model if available

-d64 use a 64-bit data model if available

-client to select the "client" VM

-server to select the "server" VM

-hotspot is a synonym for the "client" VM [deprecated]

The default VM is server,

because you are running on a server-class machine.

-cp <class search path of directories and zip/jar files>

-classpath <class search path of directories and zip/jar files>

A : separated list of directories, JAR archives,

and ZIP archives to search for class files.

-D<name>=<value>

set a system property

-verbose[:class|gc|jni]

enable verbose output

-version print product version and exit

-version:<value>

require the specified version to run

-showversion print product version and continue

-jre-restrict-search | -jre-no-restrict-search

include/exclude user private JREs in the version search

-? -help print this help message

-X print help on non-standard options

-ea[:<packagename>...|:<classname>]

-enableassertions[:<packagename>...|:<classname>]

enable assertions

-da[:<packagename>...|:<classname>]

-disableassertions[:<packagename>...|:<classname>]

disable assertions

-esa | -enablesystemassertions

enable system assertions

-dsa | -disablesystemassertions

disable system assertions

-agentlib:<libname>[=<options>]

load native agent library <libname>, e.g. -agentlib:hprof

see also, -agentlib:jdwp=help and -agentlib:hprof=help

-agentpath:<pathname>[=<options>]

load native agent library by full pathname

-javaagent:<jarpath>[=<options>]

load Java programming language agent, see java.lang.instrument

-splash:<imagepath>

show splash screen with specified image

java install successfull

4.打开编辑器.windows用户使用notepad,linux直接vi

(Eclipse 或者 Jbuilder 是常见的java开发工具)

写下一个小程序

public class Test {

public static void main(String[] args){

System.out.println("hello java");

}

}

保存到 E:\

名字为Test.java 路径 E:\Test.java

打开命令行

输入

E:

E:\ javac Test.java

E:\ java Test

结果:

hello java

https://java-er.com/blog/java-hello/