java - What to use activity_main or content_main?

Question

I am new in programming , I started learning java and worked with eclipse some time and know the very basics . Recently I started working with android studio and I have not used any other version except the 2.2.2 for very short period , and now the newest 2.2.3 . I am watching old tutorials and they work in activity_main , so my questions are :

1.In the newest version , should I work in the activity_main or in the content_main ?

2. In the activity_main the drag n drop function is not working , I can't move anything from palette to the screen to where i want (it goes directly in top left on the screen ). But in the content_main i can move once , and the second time the object puts itself in top left of the screen . How can i solve this and what is the problem ?

Also I want to ask , if you can give me some new great pdf or tutorials to learn . Thanks .

Answer 1

You should add code in the content_main XML file of your project. Content_main is actually the file containing the most of the UI of your MainActivity,except your navigation/toolbar. If at the beginning you are uncomfortable then instead of creating project with Blank activity, use Empty Activity shown in Figure

This will give you just only one activity_main XML file to work with. With time you will eventually understand the usage of Blank Activity as well.