问题
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?
回答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.
回答2:
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
回答3:
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
回答4:
The command prompt wouldn't use JAVA_HOME to find javac.exe, it would use PATH.
回答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.
回答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!!
回答7:
use this command /usr/libexec/java_home to check the JAVA_HOME
回答8:
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
回答9:
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..
来源：https://stackoverflow.com/questions/2025290/what-is-java-home-how-does-the-jvm-find-the-javac-path-stored-in-java-home