Develop Reference

What does the `this#classname` mean in Kotlin?

I am making a custom view for Android.
I am going to clone the layout by calling clone (this), but it shows error, when I use clone (this#mycustomclassname), it works.
It's still confused. Anyone knows the meaning of this#classname in kotlin?

This is a qualified this. You can access this from an outer scope.
As this can mean different things (part the referenced page):
To denote the current receiver, we use this expressions:
In a member of a class, this refers to the current object of that class.
In an extension function or a function literal with receiver this denotes the receiver parameter that is passed on the left-hand side of
a dot.

How to use method By.clazz from UIAutomator test framework

I'm using UIAutomator test framework for long tests (concerning to my acceptance test). And I need to wait until some activity is started.
I decided to use By.clazz (android.support.test.uiautomator package) methods to find activity object. I expected that something like
uiDevice.wait(Until.findObject(By.clazz(SomeActivity.class)), 30000);
will work. But it doesn't. I suppose that object of my activity cannot be found. I tried to use other By.clazz methods with different params but without success.
So, my code is pretty simple:
UiDevice uiDevice = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation());
/*.... do something...
like click on buttons which will open some activities...
*/
//does not work, time value just for sample
uiDevice.wait(Until.findObject(By.clazz(SomeActivity.class)), 30000);
I found workaround solution with using By.res, like
uiDevice.wait(Until.findObject(By.res(BASIC_PACKAGE, "someMainIdInSomeFragment")), 30000);
But I have very complicated structure of the app with base activities and so on. I often have the same layout for different activities with load different fragments. So I need to know that we started exactly SomeActivity ,regardless of loaded fragments.
So, the questions are:
Is it possible to use By.clazz for Activity to find its object?
Is there some another way to find activity object with UIAutomator?
Did I do everything right? Or maybe there are some mistakes? Is it possіble to do with UiAutomator?
Thanks!

Using class with UiObject2
Find the EditText, make sure to click on it (legacySetText would do it implicitly), and set your text.
val input = By.clazz(EditText::class.java.canonicalName)
device.wait(Until.findObject(input), TIMEOUT).apply {
click()
text = "your_text"
}
Yes, could be done through the id.
// android:id="#+id/widget_id"
By.res(applicationId, "widget_id")
Your syntax seems good to me. Just make sure no spinner (or any other widget) is blocking your view during the click attempt.

Runtime: detect all classes from a given package and call certain methods (static and non-static) for each of the classes found

We here (two small teams) are writing an Android library (OpenGL ES 3.1 based graphics effects library, but that's irrelevant to the question). One team writes the Core part (this code ends up in the (*.library.core package) , while another writes the individual effects (each effect is a single .java file in *.library.effects package + some shader code).
Currently the development works like this: each time a new effect gets written (lets say the class that implements it is called EffectBlahBlah), the Core team has to go over their code and, in one place, add a call to a static method EffectBlahBlah.init(), in another place - a call to another static method EffectBlahBlah.getUniforms(), etc etc. There are AFAIK 7 different places where we have to add 7 different calls to certain (static and non-static) methods from the new effect.
Now - having to add 7 lines of code is not the end of the world; however (especially in light of the fact that we are hoping to open the development of the effect part to outside programmers) we are hoping to automatize this in the following way:
have the Core scan the *.library.effect package and come up with a
list of all Effect classes that are there (we know how to do this)
in each of those 7 places in our code, automatically call the
appropriate method for each discovered class.
Now, if not for the static methods (which have to be there) I'd know how to do this: have all Effects extend an abstract class (lets say 'BaseEffect') which declares the 7 methods abstract, in each of the 7 places instantiate each effect in a loop using Class.forName(), cast it to a BaseEffect and call the appropriate method.
However Java does not allow abstract methods to be static. What do you recommend then?

You can use reflection for this. A possible sequence of calls is roughly:
Use Class.forName(name) to get the Class instance describing your class.
Call getMethods() on the Class instance to get the list of methods (or getMethod() to directly get a method, if you can figure out how to use it).
For the entries in the returned list of Method instances, use getModifiers() to check if it's static, and getName() to identify a specific method.
Once you found the desired Method instance, call the invoke() method on it to call the method. For static methods, you can use null for the receiver (first argument).

Activity is getting too large and becoming more and more difficult to work with. Solutions to solve this issue?

I am working on my second Android Application, first being, hello world. The application code is quite crazy looking because I love to test new libraries and ideas in it. I have been working on this application for well over 3 months and one of my activities is getting way to large and difficult to work with. I find myself getting lost in the code and it is taking longer to do simple things. There might be simple solutions to solving this issue. I really want to split my activity into two and reference each other if possible. Is there are any suggestions to simplifying and organizing code that would be greatly helpful. Even example will help me very much.
Part of my activity is adding a ton of data into a database and the other part is a long equation with multiple values. Another part is implementing the HoloGraphLibrary (Which I love). It is also implementing a listView with custom adapter. It also has a custom dialog............ I can go on and on. I hope you get my point.
EDIT
Going to work with this.
HoloGraphHelper holoGraph = new HoloGraphHelper();
holoGraph.initialize();

Try creating classes for each responsibility.
A Database Helper that has functions to insert data too:
DatabaseHelper database = new DatabaseHelper();
database .insertData(whatever);
A HoloGraphHelper that initializes the HoloGraph
HoloGraphHelper holoGraph = new HoloGraphHelper();
holoGraph.initialize();
And so on.

Break into multiple files. First classes defined in the Activity like the adapter. Change anonymous classes to classes defined in their own file. Look for ways to break out other related code into a class.

Right click on src folder of your Project and select new - class to create a new class. You can use a class for storing methods but you won't be able to display anything on screen.
To display contents to user, you can create a new Activity bu pressing Ctrl + N and selecting Android - Android Activity.

The best way is modularise your code.
I.e split your code into various related modules, for example a separate class for each part that your testing. So you could have a database entry class, a class for Gui testing, i.e. for your custom dialog. That class does all the work for that test, into various functions, I always try to keep functions as small as possible as they are easy to read.
As an example for your database entry, you could have a function which checks the database if the record already exists and then insert it. But a better way would be your insert function only performs the insert code and instead within this function it calls CheckIfDatAlreadyExists function which can return a bool so you know whether you should go ahead and insert the record. This would keep the code tidy and clean to manage.
Then from your main activity all would need to do is instantiate the relative class and call the relevant method.

Android Minesweeper project(from codeproject.com)

Here is the link of the Minesweeper project on codeproject.com.
I just wanted to ask one thing here. I completely understood the logic and algorithm this guy used, but when he called the showMineField() method inside startNewGame() method , he called it after createMineField(). I am really confused! Shouldn't the layout be set before setting up mines and handling the user click events? But the code seems to work fine. If I just call showMineField() inside startNewGame() , it gives me NullPointerException.

This is because you cannot show a mine field before creating all the objects.
It is like trying to run without legs. If you call showMineField() that is using objects that have not been initialized. Thats why you are recieving a NUllPointerException. Nullpointer is throws when a method is trying to be call on an object that has not been created yet. createminefield() initialzes everything so that nullpointer is not thrown