NullPointerException during report generation
Status: Alpha
Brought to you by:
lkuehne
Menu
▾
▴
#6 NullPointerException during report generation
I've been adding a clirr target to the log4j build file
and have been encountering a NullPointerException when
attempting to generate a compatibility report.
The kludgy patch attached fix the problem for me, but
doesn't explain why BCEL was throwing a NPE. The
underlying problem may be in BCEL.
Stack trace as follows:
C:\workspace\trunk\build.xml:804:
java.lang.NullPointerException
at org.apache.tools.ant.Task.perform(Task.java:373)
at org.apache.tools.ant.Target.execute(Target.java:341)
at
org.apache.tools.ant.Target.performTasks(Target.java:369)
at
org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at
org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at
org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
at
org.apache.tools.ant.Project.executeTargets(Project.java:1068)
at org.apache.tools.ant.Main.runBuild(Main.java:668)
at org.apache.tools.ant.Main.startAnt(Main.java:187)
at
org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
at
org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)
Caused by: java.lang.NullPointerException
at
org.apache.bcel.classfile.JavaClass.getAllInterfaces(JavaClass.java:808)
at
net.sf.clirr.core.internal.bcel.BcelJavaType.getAllInterfaces(BcelJavaType.java:78)
at
net.sf.clirr.core.internal.checks.InterfaceSetCheck.check(InterfaceSetCheck.java:58)
at
net.sf.clirr.core.Checker.runClassChecks(Checker.java:190)
at net.sf.clirr.core.Checker.reportDiffs(Checker.java:136)
at net.sf.clirr.ant.AntTask.execute(AntTask.java:303)
at
org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
at org.apache.tools.ant.Task.perform(Task.java:364)
... 10 more
--- Nested Exception ---
java.lang.NullPointerException
at
org.apache.bcel.classfile.JavaClass.getAllInterfaces(JavaClass.java:808)
at
net.sf.clirr.core.internal.bcel.BcelJavaType.getAllInterfaces(BcelJavaType.java:78)
at
net.sf.clirr.core.internal.checks.InterfaceSetCheck.check(InterfaceSetCheck.java:58)
at
net.sf.clirr.core.Checker.runClassChecks(Checker.java:190)
at net.sf.clirr.core.Checker.reportDiffs(Checker.java:136)
at net.sf.clirr.ant.AntTask.execute(AntTask.java:303)
at
org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
at org.apache.tools.ant.Task.perform(Task.java:364)
at org.apache.tools.ant.Target.execute(Target.java:341)
at
org.apache.tools.ant.Target.performTasks(Target.java:369)
at
org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at
org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at
org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
at
org.apache.tools.ant.Project.executeTargets(Project.java:1068)
at org.apache.tools.ant.Main.runBuild(Main.java:668)
at org.apache.tools.ant.Main.startAnt(Main.java:187)
at
org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
at
org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)
Total time: 2 seconds
Kludgy patch
Logged In: YES
user_id=401384
Thanks for the patch, but that just hides the problem
instead of fixing it.
I had a quick look at the code in BCEL, and I guess the
problem is this lovely error handling code for a
ClassNotFoundException in BCEL's
org.apache.bcel.classfile.JavaClass:
public JavaClass[] getInterfaces() {
// ...
try {
// ...
}
} catch(ClassNotFoundException e) {
System.err.println(e);
return null; // <---- lk: lovely
}
//...
}
public JavaClass[] getAllInterfaces() {
// ...
while(...) {
// ...
JavaClass[] interfaces = clazz.getInterfaces();
//...
for(int i = 0; i < interfaces.length; i++) { // <--
lk: boom
//...
}
}
}
You might want to check your classpath setup instead of
using your workaround, but I guess we really need to replace
BCEL with a more mature alternative to fix this.
Logged In: YES
user_id=27193
I guess I forgot to do a follow up on this. The bug is in BCEL and had already
been resolved in the SVN HEAD. So using clirr-0.6.jar and a built from the SVN
version of BCEL will avoid the problem.
Logged In: YES
user_id=401384
Thanks for the follow up, and indeed the BCEL code looks
much better now (even though this is a source incompatible
change, as getAllInterfcaes now throws a checked exception).
I'll upgrade BCEL as soon as a bugfix release becomes available.
Leaving this bug open as a reminder.
Logged In: YES
user_id=401384
Clirr now uses ASM instead of BCEL.