Q: How to add colored border on cardview? I am new to Android and this is my first question here.
I am trying to add a colored vertical border at the beginning of the cardview. How can I achieve it on xml ? I tried adding it with empty textview but it is messing up the whole cardview itself. Please check the picture link posted below for example.

activity_main.xml
<android.support.v7.widget.CardView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    card_view:contentPadding="16dp"
    card_view:cardElevation="2dp"
    card_view:cardCornerRadius="5dp">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Headline"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Title" />

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Body1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Content here" />
            
    </LinearLayout>

</android.support.v7.widget.CardView>

Many thanks

A: my solution:
create a file card_view_border.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="@color/white_background"/>
<stroke android:width="2dp" 
    android:color="@color/red" />
<corners android:radius="20dip"/>
</shape>

and set programmatically
cardView.setBackgroundResource(R.drawable.card_view_border);


A: I would like to improve the solution proposed by Amit. I'm utilizing the given resources without adding additional shapes or Views. I'm giving CardView a background color and then nested layout, white color to overprint yet with some leftMargin...
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    card_view:cardElevation="2dp"
    card_view:cardBackgroundColor="@color/some_color"
    card_view:cardCornerRadius="5dp">


    <!-- The left margin decides the width of the border -->

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:layout_marginLeft="5dp"
        android:background="#fff"
        android:orientation="vertical">

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Headline"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Title" />

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Body1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Content here" />

    </LinearLayout>

</android.support.v7.widget.CardView>


A: try doing:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    card_view:cardElevation="2dp"
    card_view:cardCornerRadius="5dp">

    <FrameLayout
        android:background="#FF0000"
        android:layout_width="4dp"
        android:layout_height="match_parent"/>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:orientation="vertical">

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Headline"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Title" />

        <TextView
            style="@style/Base.TextAppearance.AppCompat.Body1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Content here" />

    </LinearLayout>

</android.support.v7.widget.CardView>

this removes the padding from the cardview and adds a FrameLayout with a color. You then need to fix the padding in the LinearLayout then for the other fields
Update 
If you want to preserve the card corner radius create card_edge.xml in drawable folder:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <solid android:color="#F00" />
    <size android:width="10dp"/>
    <padding android:bottom="0dp" android:left="0dp" android:right="0dp" android:top="0dp"/>
    <corners android:topLeftRadius="5dp" android:bottomLeftRadius="5dp"
        android:topRightRadius="0.1dp" android:bottomRightRadius="0.1dp"/>
</shape>

and in the frame layout use  android:background="@drawable/card_edge"

A: Start From the material design update, it support app:strokeColor and also app:strokeWidth. see more
to use material design update. add following code to build.gradle(:app)
dependencies {
    // ...
    implementation 'com.google.android.material:material:1.0.0'
    // ...
  }

and Change CardView to MaterialCardView

A: As the accepted answer requires you to add a Frame Layout, here how you can do it with material design.
Add this if you haven't already
implementation 'com.google.android.material:material:1.0.0'

Now change to Cardview to MaterialCardView
<com.google.android.material.card.MaterialCardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
app:cardCornerRadius="8dp"
app:cardElevation="2dp"

app:strokeWidth="1dp"
app:strokeColor="@color/black">

Now you need to change the activity theme to Theme.Material. If you are using Theme.Appcompact I will suggest you to move to Theme.Material for future projects for having better material design in you app.
    <style name="AppTheme" parent="Theme.MaterialComponents.DayNight">


A: I think this solution may not be efficient but it serves the purpose and adds flexibility with the border width.
 <android.support.v7.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="40dp"
    android:layout_gravity="center"
    card_view:cardBackgroundColor="@color/some_color"
    card_view:cardCornerRadius="20dp"
    card_view:contentPadding="5dp"> <!-- Change it to customize the border width -->

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        card_view:cardCornerRadius="20dp"
        card_view:contentPadding="5dp">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

         <!-- Add your UI elements -->

        </RelativeLayout>
    </android.support.v7.widget.CardView>
</android.support.v7.widget.CardView>


A: CardView extends FrameLayout, so it support foreground attribute. Using foreground attribute can also add border easily.
layout as follows:
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/link_card"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:foreground="@drawable/bg_roundrect_ripple_light_border"
    app:cardCornerRadius="23dp"
    app:cardElevation="0dp">
</androidx.cardview.widget.CardView>


bg_roundrect_ripple_light_border.xml
<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="@color/ripple_color_light">

    <item>
        <shape android:shape="rectangle">
            <stroke
                android:width="0.5dp"
                android:color="#DDDDDD" />
            <corners android:radius="23dp" />
        </shape>
    </item>

    <item android:id="@android:id/mask">
        <shape android:shape="rectangle">
            <corners android:radius="23dp" />
            <solid android:color="@color/background" />
        </shape>
    </item>

</ripple>


A: I solved this by putting two CardViews in a RelativeLayout. One with background of the border color and the other one with the image. (or whatever you wish to use)
Note the margin added to top and start for the second CardView. In my case I decided to use a 2dp thick border.
            <android.support.v7.widget.CardView
            android:id="@+id/user_thumb_rounded_background"
            android:layout_width="36dp"
            android:layout_height="36dp"
            app:cardCornerRadius="18dp"
            android:layout_marginEnd="6dp">

            <ImageView
                android:id="@+id/user_thumb_background"
                android:background="@color/colorPrimaryDark"
                android:layout_width="36dp"
                android:layout_height="36dp" />

        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView
            android:id="@+id/user_thumb_rounded"
            android:layout_width="32dp"
            android:layout_height="32dp"
            app:cardCornerRadius="16dp"
            android:layout_marginTop="2dp"
            android:layout_marginStart="2dp"
            android:layout_marginEnd="6dp">

        <ImageView
            android:id="@+id/user_thumb"
            android:src="@drawable/default_profile"
            android:layout_width="32dp"
            android:layout_height="32dp" />

        </android.support.v7.widget.CardView>


A: You can keep <androidx.cardview.widget.CardView
with android:foreground="@drawable/black_border"
black_border :
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@color/white" />
    <stroke
        android:width="1dp"
        android:color="@android:color/black" />
</shape>

