Question

I would like to instantiate a new class object form external location collected from user input. The program asks the user where the file is, say /tmp/MyTestClass.java. I would then like it to grab that .java file and make it a usable class with in the program. so i could call something like MyClass = new MyTestclass(). I’ve been looking around and can’t seem to find an answer or if its even possible? Any information would be useful.

Thanks!!

———–EDIT—————

I may have been over thinking my problem. This is for a JUnit test (sorry should have mentioned this before). Below is an example of what i was using to pull in my static class. I would like to be able to dynamically pull the JUnit test file from user input. testcastjunit was the name of the class. I need to be able to programmaticly get the class from the users input and run the test case.

org.junit.runner.Result result = JUnitCore.runClasses(**testcastjunit.class**);
            for (Failure failure : result.getFailures()) {
                System.out.println(failure.toString());
            }

Answer 1

If I have understood you, this is what you need:

JavaCompiler jCompiler = ToolProvider.getSystemJavaCompiler();
List<String> options = Arrays.asList(
                           "-d", "./bin/",
                           path+".java");
int compilationResult = jCompiler.run(null, null, null, 
                options.toArray(new String[options.size()]));
if (compilationResult == 0) {
    mensaje = "Compiled the "+path+" to its .class";
    ClassLoader cLoader = ClassLoader.getSystemClassLoader();
    try {
        cLoader.loadClass("THE CLASS");
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
} else {
    mensaje = "Couldnt compile.";
}

This would work for you:

1. It gets the java compiler to compile a class.
2. Creates the options, the -d is wherever you want to put the .class once compiled and the second one is the path of your .java file.
3. Compiles, and if compilation is successfull it loads the class.
4. Start using your class!