Method with_classloader_of_activity

rust/src/api/mod.rs:1840–1852

Instructs j4rs to use the classloader associated to the specified `jobject` when searching for classes. Useful for pure native Android apps. As described in Android documentation, the native libraries that spawn new threads cannot locate and use Java classes correctly. From the [docs]((https://developer.android.com/training/articles/perf-jni#faq:-why-didnt-findclass-find-my-class)): > You can

(
        &'a mut self,
        jobject_within_valid_classloader: jobject,
    )

    /// proper classloader and use it when needed.
    /// #[cfg(target_os = "android")]
    pub fn with_classloader_of_activity(
        &'a mut self,
        jobject_within_valid_classloader: jobject,
    ) -> &'a mut JvmBuilder<'a> {
        self.jobject_within_valid_classloader_opt = Some(jobject_within_valid_classloader);
        // If the `jobject_within_valid_classloader_opt` is provided, it means that the object's classloader
        // should be used to load classes in case the traditional `FindClass` invocations fail.
        // Apply here the needed configuration for it to happen.
        // Do not detach the thread on drop. This would make the Activity to fail.
        let tmp = self.detach_thread_on_drop(false);
        let tmp = tmp.with_no_implicit_classpath();
        tmp
    }

    /// `j4rs` uses a custom ClassLoader (namely the `J4rsClassLoader`),
    /// that allows adding jars to the classpath during runtime, after the underlying `JVM` is initialized.