Naming rules for Android resources

where can I find the naming rules for Android resources? I found out thanks to compilation errors that I must use characters within [a-z0-9._], but I also have an error with an image named 401.png. When using it in my layout using

@drawable/401

I get the following compilatio开发者_JAVA百科n error:

invalid VariableDeclaratorId

I can't find these rules in the doc, and I'd like to know all of them before naming my files.

Thanks

The rules are the same as for Java identifiers since each resource must have a corresponding ID field generated in the R.java file.

Worth noting that: "File-based resource names must contain only lowercase a-z, 0-9, or underscore" characters. (quoted from compile error code).

The number is not allowed as first char of resource also not any capital letter

Your convention is correct, except that you can't start your file names with a number.

Naming rules for resources are the same as for the variables, except the case-sensitivity. In your case, problem is the first character is number.

This is Java rule, not Android-only rule. Name each element with a starting letter, and you'll be right.