Change the circle color of radio button

Question

It is simpler just setting the buttonTint color (only works on API level 21 or above):

<RadioButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/radio"
    android:checked="true"
    android:buttonTint="@color/your_color"/>

In your values/colors.xml file, put your color, in this case a reddish one:

<color name="your_color">#e75748</color>

Result:

If you want to do it by code (also API 21 and above):

if(Build.VERSION.SDK_INT >= 21)
{
    ColorStateList colorStateList = new ColorStateList(
            new int[][]
            {
                new int[]{-android.R.attr.state_enabled}, // Disabled
                new int[]{android.R.attr.state_enabled}   // Enabled
            },
            new int[]
            {
                Color.BLACK, // disabled
                Color.BLUE   // enabled
            }
        );

    radio.setButtonTintList(colorStateList); // set the color tint list
    radio.invalidate(); // Could not be necessary
}

Update:

1. use this one instead

   <android.support.v7.widget.AppCompatRadioButton
        android:id="@+id/rbtn_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:buttonTint="@color/primary" />
   

2. Then add this line into parent layout or Alt + Enter in Android Studio to auto-add xmlns:app="http://schemas.android.com/apk/res-auto"

A minimum example should look like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <android.support.v7.widget.AppCompatRadioButton
        android:id="@+id/rbtn_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:buttonTint="@color/primary" />

</LinearLayout>

3. In your program, you should call it like this: AppCompatRadioButton radioButton = (AppCompatRadioButton) view.findViewById(R.id.rbtn_test);

Basically, this kind of pattern can be applied for all AppCompact types such as AppCompatCheckBox, AppCompatButton, and so on.

Old Answer:

In order to support below android API 21, you can use AppCompatRadioButton. Then use setSupportButtonTintList method to change the color. This is my code snippet to create a radio button.

    AppCompatRadioButton rb;
    rb = new AppCompatRadioButton(mContext);

    ColorStateList colorStateList = new ColorStateList(
            new int[][]{
                    new int[]{-android.R.attr.state_checked},
                    new int[]{android.R.attr.state_checked}
            },
            new int[]{

                    Color.DKGRAY
                    , Color.rgb (242,81,112),
            }
    );
    rb.setSupportButtonTintList(colorStateList);

Tested result at API 19:

See the Android reference link for more detail.

<android.support.v7.widget.AppCompatRadioButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:buttonTint="@color/Color" />

This is working on API pre 21 as well as post 21.

In your styles.xml put:

<!-- custom style -->
<style name="radionbutton"
       parent="Base.Widget.AppCompat.CompoundButton.RadioButton">
    <item name="android:button">@drawable/radiobutton_drawable</item>
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">false</item>
    <item name="android:backgroundDimEnabled">true</item>
</style>

Your radio button in XML should look like:

<RadioButton
    android:layout_width="wrap_content"
    style="@style/radionbutton"
    android:checked="false"
    android:layout_height="wrap_content"
    />

Now all you need to do is make a radiobutton_drawable.xml in your drawable folder. Here is what you need to put in it:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:drawable="@drawable/radio_unchecked" android:state_checked="false" android:state_focused="true"/>
  <item android:drawable="@drawable/radio_unchecked" android:state_checked="false" android:state_focused="false"/>
  <item android:drawable="@drawable/radio_checked" android:state_checked="true" android:state_focused="true"/>
  <item android:drawable="@drawable/radio_checked" android:state_checked="true" android:state_focused="false"/>
</selector>

Your radio_unchecked.xml file:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
  android:shape="oval">
  <stroke android:width="1dp" android:color="@color/colorAccent"/>
  <size android:width="30dp" android:height="30dp"/>
</shape>

Your radio_checked.xml file:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
  <item>
    <shape android:shape="oval">
      <stroke android:width="1dp" android:color="@color/colorAccent"/>
      <size android:width="30dp" android:height="30dp"/>
    </shape>
  </item>
  <item android:top="5dp" android:bottom="5dp" android:left="5dp" android:right="5dp">
    <shape android:shape="oval">
      <solid android:width="1dp" android:color="@color/colorAccent"/>
      <size android:width="10dp" android:height="10dp"/>
    </shape>
  </item>
</layer-list>

Just replace @color/colorAccent with the color of your choice.