什么是 JAVA_HOME？ JVM如何找到存储在JAVA_HOME中的javac路径？

Question

I would like to know what is JAVA_HOME. Where do I set the path of javac.exe and java.exe. It is in environment variables. When I compile a Java program from command prompt, how does the JVM find javac.exe ?

Answer 1

JVM does not find java.exe . It doesn't even call it. java.exe is called by the operating system (Windows in this case).

JAVA_HOME is just a convention, usually used by Tomcat, other Java EE app servers and build tools such as Gradle to find where Java lives.

The important thing from your point of view is that the Java /bin directory be on your PATH so Windows can find the .exe tools that ship with the JDK: javac.exe , java.exe , jar.exe , etc.

Answer 2

JAVA_HOME and JRE_HOME are not used by Java itself. Some third-party programs (for example Apache Tomcat) expect one of these environment variables to be set to the installation directory of the JDK or JRE . If you are not using software that requires them, you do not need to set JAVA_HOME and JRE_HOME . PATH is an environment variable used by the operating system (Windows, Mac OS X, Linux) where it will look for native executable programs to run. You should add the bin subdirectory of your JDK installation directory to the PATH , so that you can use the javac and java commands and other JDK tools in a command prompt window. Courtesy : coderanch

Answer 3

set environment variable

JAVA_HOME=C:\Program Files\Java\jdk1.6.0_24

classpath=C:\Program Files\Java\jdk1.6.0_24\lib\tools.jar

path=C:\Program Files\Java\jdk1.6.0_24\bin

Answer 4

命令提示符不会使用 JAVA_HOME 来查找 javac.exe，而是使用 PATH。

Answer 5

JAVA_HOME is a environment variable (in Unix terminologies), or a PATH variable (in Windows terminology). A lot of well behaving Java applications (which need the JDK/JRE) to run, looks up the JAVA_HOME variable for the location where the Java compiler/interpreter may be found.

Answer 6

JAVA HOME is used for setting up the environment variable for JAVA. It means that you are providing a path for compiling a JAVA program and also running the same. So, if you do not set the JAVA HOME( PATH ) and try to run a java or any dependent program in the command prompt.

You will deal with an error as javac : not recognized as internal or external command . Now to set this, Just open your Java jdk then open bin folder then copy the PATH of that bin folder.

Now, go to My computer right click on it----> select properties-----> select Advanced system settings----->Click on Environment Variables------>select New----->give a name in the text box Variable Name and then paste the path in Value.

That's All!!

Answer 7

JAVA_HOME is an environment variable which is read by some development tools like Apache Tomcat, Apache Maven, Gradle, Jenkins etc. Usually, JAVA_HOME is set to point to JDK instead of JRE because these development tools need to use tools like compiler, debugger, document generator etc. which are only available in JDK since JDK is a development kit. JRE is only meant for running java applications. JDK = JRE + Development tools

Consumer facing Java applications don't read JAVA_HOME variable and they just need to know where the JVM is located and that's why JVM location (directory) needs to be added to the PATH variable. This is automatically done for you when you install Java software. Whenever you try to run a Java application by either double clicking on the app or through command line, your operating system reads PATH variable to locate and run JVM and it doesn't look for JAVA_HOME variable.

Answer 8

使用此命令 /usr/libexec/java_home 检查 JAVA_HOME

Answer 9

JAVA_HOME is an Environment Variable set to the location of the Java directory on your computer. PATH is an internal DOS command that finds the /bin directory of the version of Java that you are using. Usually they are the same, except that the PATH entry ends with /bin

Answer 10

Basically JAVA_HOME is use to set path of the java . it is use in windows. it's used for set path of the multiple software like as java EE , ANT and Maven . this is the steps to solve your problem:

only for core java to set path : path : "C:\Program Files\Java\jre1.8.0_77\bin" but when you are use multi built like as ANT , core java then you are used JAVE_HOME in environment .

follow the steps :

JAVA_HOME : "C:\Program Files\Java\jre1.8.0_77\bin" ANT_HOME : "C:\ant\apache-ant-1.9.6"

Path: JAVA_HOME , ANT_HOME ; it is the systematic way to set the environment variable..