"add cast to TextView"

Well, casting means that you need to change the object to another object. In Java, everything is an object. from your question

TextView answerLabel = findViewById(R.id.textView1);

If it is asking you to add a cast. Usually eclipse will give the option to automatically cast it. consider the following:

String hello = "hello";

which I think is correct.

If you say

String hello = 0;

it might ask for a cast.

We can cast to a string like this

String hello = (String) 0;

or

String hello = ""+0;

both ways should work.

So in your question

TextView answerLabel = findViewById(R.id.textView1);

you might need something like

TextView answerLabel = (TextView) findViewById(R.id.textView1);

or if the problem is inside the findViewById() you might need to cast inside it instead.

TextView answerLabel = findViewById((String)R.id.textView1);

Since I have not seen your code I am guessing here, I wanted to know if you get the concept of what I saying. Apples to Apples and Bananas to Bananas, when in object matters.

Also if Apples and Bananas are children of the class Fruit. and the receiving object needs a Fruit class, then you can say

Fruit fruit = new Apple();

that should also work.

OK, I underestand it now what it is.

My code was the same like in the video - just one text and one button, but I couldn't add the cast. Now I know hot to change it: ctrl + shift + o

Is there any other way to solve the problem like mine?

It would be better if I can look at your code to see what is it what you are talking about. Can you post it somewhere like in github, or can you a a remote desktop session ?

Yeasterday I spent the whole day, but stil I can not use github. Maybe will be easier with using remote desktop session? But I don't know what should I put in the field: "computer"? I didn't do it before.

If you have skype, we can start there. Send me your skype id. Then I can guide you to all this one step at a time.

my id is: marcin,dlubis

thanks :)