Resource types in Android app Android 01.02.2018

Resources are the additional files and static content that your code uses, such as bitmaps, layout definitions, user interface strings, animation instructions, and more.

You should always externalize resources such as images and strings from your application code, so that you can maintain them independently. Externalizing your resources also allows you to provide alternative resources that support specific device configurations such as different languages or screen sizes, which becomes increasingly important as more Android-powered devices become available with different configurations. In order to provide compatibility with different configurations, you must organize resources in your project's res/ directory, using various sub-directories that group resources by type and configuration.

Here's a brief summary of each resource type:

• Animation Resources. Define pre-determined animations. Tween animations are saved in res/anim/ and accessed from the R.anim class. Frame animations are saved in res/drawable/ and accessed from the R.drawable class.
• Color State List Resource. Define a color resources that changes based on the View state. Saved in res/color/ and accessed from the R.color class.
• Drawable Resources. Define various graphics with bitmaps or XML. Saved in res/drawable/ and accessed from the R.drawable class.
• Layout Resource. Define the layout for your application UI. Saved in res/layout/ and accessed from the R.layout class.
• Menu Resource. Define the contents of your application menus. Saved in res/menu/ and accessed from the R.menu class.
• String Resources. Define strings, string arrays, and plurals (and include string formatting and styling). Saved in res/values/ and accessed from the R.string, R.array, and R.plurals classes.
• Style Resource. Define the look and format for UI elements. Saved in res/values/ and accessed from the R.style class.
• Font Resources. Define font families and include custom fonts in XML. Saved in res/font/ and accessed from the R.font class.
• More Resource Types. Define values such as booleans, integers, dimensions, colors, and other arrays. Saved in res/values/ but each accessed from unique R sub-classes (such as R.bool, R.integer, R.dimen, etc.).

String Resources

A string resource provides text strings for your application with optional text styling and formatting. There are three types of resources that can provide your application with strings:

• String. XML resource that provides a single string.
• String Array. XML resource that provides an array of strings.
• Quantity Strings (Plurals). XML resource that carries different strings for pluralization.

To allow the app using formatted strings from resources you can use following snippet

<string name="app_ver">SuperApp, ver. %1$d</string>

and in code

String ver = getResources().getString(R.string.app_ver, 7);

How to use float value in dimen resource type

Declare in dimen.xml

<resources>
    <item name="my_float_value" type="dimen" format="float">7.34</item>
</resources>

Referencing from xml

@dimen/my_float_value

Referencing from java

TypedValue typedValue = new TypedValue();
getResources().getValue(R.dimen.my_float_value, typedValue, true);
float myFloatValue = typedValue.getFloat();

How to use integer value in dimen resource type

Declare in res/values/integers.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer name="max_speed">75</integer>
    <integer name="min_speed">5</integer>
</resources>

This application code retrieves an integer:

int maxSpeed = getResources().getInteger(R.integer.max_speed);

How to get resource by name

public static Drawable getDrawable(Context context, String name) {
    int resourceId = context.getResources().getIdentifier(name, "drawable", context.getPackageName());
    return context.getResources().getDrawable(resourceId);
}