Android Resource Formatting Standards

Naming

XML generated resources (e.g. R.id.some_id) should be named in snake case. Though capitals are allowed, the compiler will reject files named with capitals. For consistency it is important to keep naming conventions the same.

Layouts

Put the xml declaration on the first line with the root tag on the second line with no indentation.
Use 4 spaces for indenting tags. Use 4 spaces for parameters.
Add a blank line between tags except for closing ViewGroup tags.
Put ID as the first parameter.
layout_width and layout_height should be at the top, in that order (below ID).
Favor ConstraintLayout and its layout helpers over nesting several layouts
Keep layout_ prefixed parameters grouped towards the top with width and height.
Keep tools: parameters grouped at the bottom.
Try to keep related items near each other (textSize, textColor; shadowColor, shadowRadius, etc..)
You may include HTML style comments if you like:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
                
    <ImageView
        android:id="@+id/char_img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:visibility="invisible"
        tools:visibility="visible"
        android:src="@drawable/img_char_bottom"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp">

        <Button
            android:id="@+id/skip_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Button.Dialog.Skip"
            android:paddingLeft="24dp"
            android:paddingRight="24dp"
            android:text="@string/skip"/>

        <Button
            android:id="@+id/next_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Button.Dialog.Next"
            android:text="@string/next"/>
    </LinearLayout>
</RelativeLayout>

Styles

Use styles whenever possible, they make for cleaner layout files.
Group related styles by name:

<style name="HorizontalLine">
    <item name="android:layout_height">1dip</item>
    <item name="android:layout_width">match_parent</item>
</style>
<style name="HorizontalLine.Estimate">
    <item name="android:background">#ff8fa2b2</item>
</style>

<style name="EstimateNote">
    <item name="android:paddingLeft">36dip</item>
</style>
<style name="EstimateTotal">
    <item name="android:textSize">60sp</item>
</style>

Try to give styles as much context as possible. Do not include color names as part of the style. This makes things difficult to understand or change if the color changes:

Bad:
<style name="Button">
    <item name="android:textColor">#ffffffff</item>
</style>
<style name="Button.Green">
    <item name="android:background">@drawable/green_button_selector</item>
</style>
<style name="Button.Blue">
    <item name="android:background">@drawable/blue_button_selector</item>
</style>

Colors

Use colors anywhere you need a color value
Keep common colors from having very little context:

Good:
<!-- Context free color definition -->
<color name="white">#ffffffff</color>
<color name="light_gray">#ffcccccc</color>
<color name="dark_gray">#ff333234</color>
<color name="dscout_teal">#ff02b2e0</color>

Bad:
<color name="ok_button_blue_color">#ff0000ff</color> <!-- This is now green? -->

When using colors that do require context they must refer to a context free color or an absolute color value:

Good:
<color name="snippet_detail_border_color">@color/white</color>
<color name="snippet_detail_bg_color">@color/light_gray</color>
<color name="snippet_question_title">@color/dscout_teal</color>
<color name="snippet_question_details">@color/dark_gray</color>

Strings

Always use a strings file when defining copy. Period. No Exceptions.
Leverage plurals and formatted string definitions when applicable. They provide a cleaner implementation than in code solutions.

Dimensions

Dimensions can provide a localized approach to common dimensions. Consider them for cases such as cell spacing used multiple places in the app. This allows for quick edits across the whole app.

Additional Information

Vokal Engineering

Quality, Integrity, and Efficiency.

Android Resource Formatting Standards

Naming

Layouts

Styles

Colors

Strings

Dimensions

Additional Information