Ant“JAVA_HOME 不指向 JDK” - 但它确实如此

Question

I cannot run my Ant build.xml since I updated to java 1.7.0_52 (or there about). I have been running it for years through Eclipse locally on my Windows 7 laptop - but with this latest jave jdk update somethings different (?).

BUILD FAILED
C:\workspace\WaterAspectsModel3\build.xml:329: 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 "D:\Morten\Java\jdk1.7.0_52"

This is my jdk! So JAVA_HOME is pointing to a jdk (as is also clear from the error message). I have my JAVA_HOME with bin folder in my path as always. I've configured Eclipse - external tools configuration - with a JRE pointing to the same D:\\Morten\\Java\\jdk1.7.0_52 (through "Separate JRE" setting). And I've tried a number of other configurations - all without luck.

I've been reading the tonnes of answers on lists here and other places and think I've tried all suggestions. Most seem to be cases where JAVA_HOME actually points to a jre and just needs to be corrected to jdk or there's a ";" in the path or something like that. None of these seem to apply in my case.

Any suggestions?

Answer 1

I was having the same message when running ANT through Eclipse.

What worked for me:

1. In Eclipse, access the menu: "Window -> Preferences";
2. Access "Ant -> Runtime", at the tree;
3. Access the Classpath tab;
4. Expand the "Global Entries" item;
5. Inside Global Entries, the path to tools.jar was wrong. It was pointing to an older version of Java;
6. I removed the wrong entry and added the correct one with "Add External Jars" button. It worked.

Answer 2

解决方案“ Had to copy C:\\Program Files\\Java\\jdk1.6.0_10\\lib\\tools.jar to C:\\Program Files\\Java\\jre6\\lib\\ext ”从这里开始非常有帮助并且对我有用。

Answer 3

The real message is that Ant can't find com.sun.tools.javac.Main .

Which, together with the fact that the latest "Sun" (Oracle) JDK is 1.7.0_13 (or maybe _14, but definitely not the "_52" that your install dir indicates), makes me think that you're not using a distribution that Ant recognizes. You can verify this by running jar tvf $JAVA_HOME/lib/tools.jar , and looking for that class.

The Ant Manual talks about ways to work with different compilers. Since I've only used "Sun" compilers, I'm afraid that I can't give you any pointers.

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Edit: you could also try setting fork="yes" in your build file. This should run the compiler executable rather than trying to invoke the compiler class.

Answer 4

尝试将JAVA_HOME\\bin添加到您的环境env PATH 。

Answer 5

将 JAVA_HOME 添加到 Eclipse-Preferences-Java-Build Path-Classpath 变量。

Answer 6

Sorry for the unearthing,

I had the same problem, my solution doesn't need any modification in environment variables, and works for a recent JDK where the tools.jar can't be found.

Just go in the small down-arrow next to the ant run button Then click "Configure external tools" Then in JRE tab Select a JDK installed on your computer, not a JRE, no problems if the selected JDK is not the same JDK/JRE as in your project.

It should be work now.