Assuming you use VS Express and C#.
The icon is set in the project properties page. To open it right click on the project name in the solution explorer. in the page that opens, there is an Application tab, in this tab you can set the icon.
There is a solution:
<resources>
<item name="text_line_spacing" format="float" type="dimen">1.0</item>
</resources>
In this way, your float number will be under @dimen. Notice that you can use other "format" and/or "type" modifiers, where format stands for:
Format = enclosing data type:
- float
- boolean
- fraction
- integer
- ...
and type stands for:
Type = resource type (referenced with R.XXXXX.name):
- color
- dimen
- string
- style
- etc...
To fetch resource from code, you should use this snippet:
TypedValue outValue = new TypedValue();
getResources().getValue(R.dimen.text_line_spacing, outValue, true);
float value = outValue.getFloat();
I know that this is confusing (you'd expect call like getResources().getDimension(R.dimen.text_line_spacing)), but Android dimensions have special treatment and pure "float" number is not valid dimension.
Additionally, there is small "hack" to put float number into dimension, but be WARNED that this is really hack, and you are risking chance to lose float range and precision.
<resources>
<dimen name="text_line_spacing">2.025px</dimen>
</resources>
and from code, you can get that float by
float lineSpacing = getResources().getDimension(R.dimen.text_line_spacing);
in this case, value of lineSpacing is 2.024993896484375, and not 2.025 as you would expected.
Best Solution
The way that the adding of an application icon is that you must select it from the local file system, and then it is embedded into the application at build time. As far as I know it is not possible to have it first pull from a resource file.