How to draw border on just one side of a linear layout?

it is also possible to implement what you want using a single layer

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:bottom="-5dp"
        android:right="-5dp"
        android:top="-5dp">
        <shape android:shape="rectangle" >
            <solid android:color="@color/color_of_the_background" />

            <stroke
                android:width="5dp"
                android:color="@color/color_of_the_border" />
        </shape>
    </item>

</layer-list>

this way only left border is visible but you can achieve any combination you want by playing with bottom, left, right and top attributes of the item element

Easy as pie, allowing a transparent bg:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:angle="0"
        android:startColor="#f00"
        android:centerColor="@android:color/transparent"
        android:centerX="0.01" />
</shape>

Change the angle to change border location:

• 0 = left
• 90 = bottom
• 180 = right
• 270 = top

You can use this to get border on one side

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
    <shape android:shape="rectangle">
        <solid android:color="#FF0000" />
    </shape>
</item>
<item android:left="5dp">
    <shape android:shape="rectangle">
        <solid android:color="#000000" />
    </shape>
</item>
</layer-list>

EDITED

As many including me wanted to have a one side border with transparent background, I have implemented a BorderDrawable which could give me borders with different size and color in the same way as we use css. But this could not be used via xml. For supporting XML, I have added a BorderFrameLayout in which your layout can be wrapped.

See my github for the complete source.