Javah tool error: Could not find class file for hellojni

I suspect the issue is that your class has a package and you are trying to run the command from the directory with the class file instead of the package root.

Samhain’s example works because his MyClass.java contains no package, whereas I suspect yours does.

For example, assume we have the following file at c:\src\com\example\MyClass.java

package com.example;

public class MyClass {
    public native void myMethod();
}

Go to the command line and execute the following:

c:\src\com\example>javac MyClass.java

c:\src\com\example>dir

 Directory of C:\src\com\example

2015-02-23  03:17 PM    <DIR>          .
2015-02-23  03:17 PM    <DIR>          ..
2015-02-23  03:20 PM               219 MyClass.class
2015-02-23  03:17 PM                84 MyClass.java

c:\src\com\example>javah MyClass
Error: Could not find class file for 'MyClass'.

c:\src\com\example>cd c:\src

c:\src>javah com.example.MyClass

c:\src>dir
 Directory of C:\src

2015-02-23  03:18 PM    <DIR>          .
2015-02-23  03:18 PM    <DIR>          ..
2015-02-23  03:16 PM    <DIR>          com
2015-02-23  03:18 PM               449 com_example_MyClass.h

Success!