Java classpath template behavior
I have used the template extension feature java -classpath
earlier and successfully. I am currently experiencing a strange problem.
The wildcard must expand to every one jar
in the named folder. Here is a quote from Oracle:
Class path entries can contain the basename wildcard character *,
which is considered equivalent to specifying a list of all the files
in the directory with the extension .jar or .JAR. For example, the
class path entry foo/* specifies all JAR files in the directory
named foo. A classpath entry consisting simply of * expands to a
list of all the jar files in the current directory.
This is a link to Oracle doc on Java 6 on the subject of classpath.
The behavior I see contradicts this. Here are 3 runs. The first one explicitly names jar
and so it works. Others use wildcard and fail. What for? This matters to me because I rely on wildcards (elsewhere) and therefore understanding this unexpected behavior is very important to me.
#!/bin/bash
printf "The EV is...\n"
echo $CLASSPATH
printf "The working directory is...\n"
pwd
printf "Directory listing...\n"
ls
printf "END of directory listing.\n"
printf "Test with named jar.\n"
java -javaagent:../sizeof/sizeof.jar -classpath ./testsizeof.jar info.zqxj.test.Tester
printf "Test with star.\n"
java -javaagent:../sizeof/sizeof.jar -classpath * info.zqxj.test.Tester
printf "Test with dot slash star.\n"
java -javaagent:../sizeof/sizeof.jar -classpath ./* info.zqxj.test.Tester
Output:
The EV is...
The working directory is...
/home/b/Documents/workspace/testsizeof
Directory listing...
bin run.sh src testsizeof.jar
END of directory listing.
Test with named jar.
40
Test with star.
Exception in thread "main" java.lang.NoClassDefFoundError: run/sh
Caused by: java.lang.ClassNotFoundException: run.sh
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: run.sh. Program will exit.
Test with dot slash star.
Exception in thread "main" java.lang.NoClassDefFoundError: //run/sh
Caused by: java.lang.ClassNotFoundException: ..run.sh
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: ./run.sh. Program will exit.
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Solution, specify the classpath argument twice. Example: -classpath "*"
This is needed both on the command line and inside a bash script.
Next addition:
Also, please note that -classpath "~/folder/*"
does not work but -classpath ~/folder/"*"
is good. Suggest a template, but don't quote ~
. You seem to need the operating system to interpret ~
, but you need to specify the pattern *
because you want to pass it in java
for extension in Java fashion.
Please note that you should not query java
for an extension *.jar
because it will lead to unintended results. The Java Specification says that the correct wildcard is only *
.
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