lst_classes.js

// start app:    adb shell monkey -p rena2019.dummyapp 1
// display pid:  frida-ps -U
// run script:   frida -U -p <pid> -l ./lst_classes.js

class_name = "rena2019.dummyapp"

if (Java.available) {
  Java.perform(function () {   
        Java.enumerateLoadedClasses({
            onMatch: function(className){
                if (className.startsWith(class_name))
                        console.log(className)
            },
            onComplete:function(){
            }
    });
  });
} else {
  send("Java not available in this process");
}