[JAVA] JAVA JDK 安装配置

JDK 安装

下载安装

• 下载JDK
  从oracle官方网站下载并安装JDK.

• 下载使用文档
  从oracle官方网站下载使用帮助文档.

• 安装库源文件
  源文件位于安装目录的 /Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home/lib/src.zip

查看已安装JDK

mac-abeen:~ abeen$ /usr/libexec/java_home -V
//已安装JDK
Matching Java Virtual Machines (3): 
    9.0.4, x86_64:	"Java SE 9.0.4"	/Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home
    1.8.0_66, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_66.jdk/Contents/Home
    1.8.0_65, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_65.jdk/Contents/Home

//默认使用JDK
/Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home  

查看版本

mac-abeen:~ abeen$ java -version
java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)
mac-abeen:~ abeen$ javac -version
javac 9.0.4

Hello World

创建Welcome.java源文件

mac-abeen:java abeen$ 
/**
 * This program dispalys Hello World 
 * @version 1.0 
 * @author ABeen
 * */

public class Welcome
{
    public static void main(String[] args)
    {
        String greeting = "Hello World!";
        System.out.println(greeting);
    }
}

编译并执行

mac-abeen:java abeen$ javac Welcome.java 
mac-abeen:java abeen$ java Welcome
Hello World!