I'm using android sdk and am trying to change the name of a string. I've started a new project, the activity_main.xml shows Hello World! on the screen.
I go into strings.xml file and there was nothing even referencing this string so I added in
<string name="hello_world">Hello World!</string>
<string name="hello_world">Helloooo Worldsss!</string>
This looks like simply a case of syntax; you need quote marks.