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javaheaderjava-native-interfaceclasspath

Generate JNI header file in different packages

If I have all my .java and .class files in one place (i.e. in the default package) then everything is OK and I do all the JNI stuff, etc. But in this case I have package-ception (lots of directories), my class and Java files are separated in /bin and /src and so on. And I need to generate the header file, but I am getting errors all the time. I tried so many commands, I saw different tutorials. I am already out of options. So my project is in c://gvk/SEP3 and then the class and Java files with the native methods that I am gonna use are in /bin/CalculatorServer and /src/CalculatorServer

I have all the time run the javah command from the directory where the class file with the native methods is. The commands I tried so far are:

javah -d ./CalculatorServer NativeMethodsCalculator

Error: Could not find class file for 'NativeMethodsCalculator'.

javah -d ./CalculatorServer CalculatorServer.NativeMethodsCalculator

Error: Could not find class file for 'CalculatorServer.NativeMethodsCalculator'.

javah -d c://gvk/SEP3/bin/CalculatorServer -classpath c://gvk/SEP3/bin/CalculatorServer NativeMethodsCalculator

Error: Could not find class file for 'NativeMethodsCalculator'.

javah -classpath c://gvk/SEP3/bin/CalculatorServer -o NativeMethodsCalc.h src.CalculatorServer.NativeMethodsCalculator

Error: Could not find class file for 'src.CalculatorServer.NativeMethodsCalculator'.

javah -jni bin.CalculatorServer.NativeMethodsCalculator

Error: Could not find class file for 'bin.CalculatorServer.NativeMethodsCalculator'.

Solution

  • What you didn't try: go just to /bin/ (not into CalculatorServer) and run

    javah -jni CalculatorServer.NativeMethodsCalculator

    This is the only way how to run it. Just look at the javah doc. It says "fully-qualified-classname" in the synopsis. "Fully qualified" means full classpath. You were giving it only the classname. It worked for you so far only because you were using a default package, which means that your fully qualified classname was equal to a bare classname.

    Option -d and -o doesn't influence the class lookup, only the storage of native result. All the variants you tried do not make any difference to your mistake.