The new javadoc correctly does not allow non ".java" files as they were in old Javadoc. Any file with non ".java" extension is rejected. But the error message needs more clarity. Please find the command and the message attached below.
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blr-sunray:/home/vr128054/jdk-latest/jdk1.4.0/src/javax/swing 654 % java -Dfile.encoding=EUC-JP -Xbootclasspath/p:/home/vr128054/gj/gjclasses3 -classpath /home/vr128054/gj/gjclasses3 com.sun.tools.javadoc.Main JPanel.xxx
Loading source files for package JPanel.xxx...
javadoc: No source files for package JPanel/xxx
1 error
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While it is perfectly valid to reject .xxx extension, by default, a "." shouldnt
be considered a package name delimiter. A filename level error message could be more informative.