JAVA_HOME does not point to the JDK

问题:

I am trying to follow a tutorial about how to use ant to build and run your application. I've followed all the steps and have created the build file, but when I try to run ant it gives me this error.

BUILD FAILED /home/bilal/tmp/ant/build.xml:19: Unable to find a javac compiler; com.sun.tools.javac.Main is not on the classpath. Perhaps JAVA_HOME does not point to the JDK. It is currently set to "/usr/lib/jvm/java-6-openjdk/jre"

Any ideas how to resolve this issue ?

回答1:

Make JAVA_HOME variable point to a jdk installation, not jre.

You are referencing the runtime environment, not the development kit - it can't find the compiler because its not there.

From the line you posted, which states you have open-jdk you can just remove the jre at end:

export JAVA_HOME='/usr/lib/jvm/java-6-openjdk/'

回答2:

You installed java...

apt-get install default-jre

But not the JDK...

apt-get install default-jdk

回答3:

This is by design. You cannot use ant's java.home (which is a java.lang.System property) interchangeably with how JAVA_HOME is set in the OS environment. You are probably trying to assert the location of the Java compiler with a fundamentally different value from a different property layer -- i.e. java.home (from Ant's Java internals) points to the Java Runtime Environment at <any_installed_java_pointed_to_by_ant>/jre while JDK_HOME (from the OS environment) is usually set to <DOWNLOADED_AND_INSTALLED_JAVA_DEVELOPMENT_KIT>.

See my question and answer here for more details: Where does Ant set its 'java.home' (and is it wrong) and is it supposed to append '/jre'?

The solution is to access the system environment property within Ant by using ${env.JAVA_HOME}. Specify which java to use explicitly in the Javac Task by setting the executable property to the javac path and the fork property to yes (see Ant's Javac Task Documentation). That way, it doesn't matter what Java environment Ant is running inside, the compiler is always clearly specified!

回答4:

I know this question is old but the accepted answer does not work anymore and since this is the fist link on google search i'll tell how i solved this problem.

for eclipse using ubuntu:

go to Window->Preferences->Ant->Runtime->Select Ant_Home_Entries and click on add external jars then find in file explorer where your jdk is (default is in /usr/lib/jvm/) and in the lib folder of your jdk you will find the tool.jar. select this one and click apply.

try to build your project and things should work!

note: i hadn't used ant for a long time but needed it for ycsb couchbase workload generator (http://www.couchbase.com/wiki/display/couchbase/Load+Generator+Setup) if anyone is/was stuck on this.

回答5:

It looks like you are currently pointing JAVA_HOME to /usr/lib/jvm/java-6-openjdk/jre which appears to be a JRE not a JDK. Try setting JAVA_HOME to /usr/lib/jvm/java-6-openjdk.

The JRE does not contain the Java compiler, only the JDK (Java Developer Kit) contains it.

回答6:

I am using Windows 7 and have struggled with the same issue. I fixed it by changing my environment variables.

To change your environment variables click here

I added ";%JAVA_HOME%/bin" to the end of paths variable and added a new "JAVA_HOME" variable and set its value to the location of my JDK "C:\Program Files\Java\jdk1.8.0_11". After that I restarted my Node.js command prompt and it worked.

Please note you JDK directory may be different then mine. Also depending on your setup, you may need to restart you computer after setting the environment variables.

回答7:

The JAVA_HOME you have above only points to the JRE, which does not contain the compiler. Set your JAVA_HOME to

/usr/lib/jvm/java-6-openjdk

...and try again.

回答8:

I had a similar problem and it turned out the issue was having both versions 6 & 7 of OpenJDK. The answer comes from r-senior on ubuntu forums (http://ubuntuforums.org/showthread.php?t=1977619) --- just uninstall version 6:

sudo apt-get remove openjdk-6-*

make sure that JAVA_HOME and CLASSPATH aren't set to anything since that isn't actually the problem.

回答9:

I just copied tools.jar file from JDK\lib folder to JRE\lib folder. Since then it worked like a champ.

回答10:

I met this issue in rhel, my "JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk"(which is a symbolic link), and ant complains.

MY solution for this is to use the real jdk path in JAVA_HOME, like:

JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64

It works for me.

回答11:

for centos yum -y install java-1.7.0-openjdk-devel.x86_64

and update JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk.x86-64

回答12:

Experienced this issue when trying to run the android emulator with Meteor 1.0 on elementary OS Luna (based on Ubuntu 12.04 LTS sources).

openjdk-6-jdk was installed, as well as the jre. In the end, not expecting any success, I tried:

sudo apt-get remove openjdk-6-*

this resulted in fully expected errors, so I followed up with

sudo apt-get install openjdk-6-jdk

and things worked. Go figure.

回答13:

On Ubuntu 14.04, I found two parts to solving the problem:

1. Remove /jre from the environment variable. For me: export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64/
2. Install the JDK as well as the JRE: sudo apt-get install default-jdk

回答14:

Once you update the JAVA_HOME path as stated in the answer, you should do this:

$source ~/.bashrc

This will refresh bashrc show the updated path in $JAVA_HOME when you check again.

回答15:

Execute:

$ export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.141-3.b16.el6_9.x86_64

and set operating system environment:

vi /etc/environment

Then follow these steps:

1. Press i

2. Paste

   JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.141-3.b16.el6_9.x86_64
   

3. Press esc

4. Press :wq

回答16:

Under Jenkins it complains like :

/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.191.b12-1.el7_6.x86_64/ doesn’t look like a JDK directory

Reason : Unable to found any Dev Kit for JDK.

Solution:

Please make sure to install openjdk-devel package as well along with your JDK-1.8* version and reexport with : # source ~/.bash_profile