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Android - Can't change action bar text colour

I'm trying to apply a custom style to the material theme action bar. Nothing fancy, just a simple change of title text colour, however I can't get the colour to change at all. I've set up a theme an app theme as follows in the themes xml:
<resources>
<style name="AppTheme" parent="Base.AppTheme">
<item name="android:navigationBarColor">?android:attr/colorPrimaryDark</item>
<item name="actionBarStyle">#style/AppBarLayout</item>
</style>
<style name="Base.AppTheme" parent="Theme.MaterialComponents.DayNight">
<item name="colorPrimary">#color/colorPrimary</item>
<item name="colorPrimaryVariant">#color/colorPrimaryDark</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorSecondary">#color/colorSecondary</item>
<item name="colorSecondaryVariant">#color/colorSecondaryDark</item>
<item name="colorOnPrimary">#color/colorTextLight</item>
<item name="colorOnSecondary">#color/colorTextDark</item>
<item name="colorError">#color/colorError</item>
</style>
</resources>
The action bar style which is referenced is defined in the styles xml as:
<style name="AppBarLayout" parent="Widget.AppCompat.ActionBar">
<item name="background">?attr/colorPrimaryDark</item>
<item name="titleTextStyle">#style/AppBarText</item>
</style>
The style which titleTextStyle references is also defined in styles xml as:
<style name="AppBarText" parent="ThemeOverlay.AppCompat.Dark.ActionBar">
<item name="android:textColor">#color/colorError</item>
</style>
I've tried other attributes in the latter style, such as:
<item name="android:titleTextStyle">#color/colorError</item>
<item name="titleTextStyle">#color/colorError</item>
<item name="colorOnPrimary">#color/colorError</item>
<item name="android:textColorPrimary">#color/colorError</item>
I've also tried applying the AppBarText style with other attributes to titleTextStyle, such as android:textAppearance. Alas - no luck.
How can I get this to change? Perhaps I'm misunderstanding how Material components work?

I am not sure if this will work but try this code once:
int labelColor = getResources().getColor(R.color.label_color);
String сolorString = String.format("%X", labelColor).substring(2); // !!strip alpha value!!
Html.fromHtml(String.format("<font color=\"#%s\">text</font>", сolorString), TextView.BufferType.SPANNABLE);
getSupportActionBar().setTitle(colorString);

MaterialComponents theme alert dialog buttons

Recently I switched from support library to com.google.android.material:material:1.0.0
But now I have a problem, in this pages there's a note https://github.com/material-components/material-components-android/blob/master/docs/getting-started.md
Note: Using a Material Components theme enables a custom view inflater which replaces default components with their Material counterparts. Currently, this only replaces Button XML components with MaterialButton.
And the theme I am using
Theme.MaterialComponents.Light.NoActionBar
does exactly what it says in that note, it replaces AlertDialog Buttons to MaterialButtons but the problem is that by default MaterialButtons are colored background and now the buttons looks like this:
How can I make them borderless and backgroundless again?
PS I am using alert builder to create alert dialogs:
android.app.AlertDialog.Builder

I figured out what was causing this problem. I need to use different AlertDialog class:
androidx.appcompat.app.AlertDialog
When I switched to this everything started working as expected. Here's where I found the solution:
https://github.com/material-components/material-components-android/issues/162

When using com.google.android.material:material:1.0.0 and androidx.appcompat.app.AlertDialog you can customize each button in the buttonBar by using Widget.MaterialComponents.Button.TextButton as parent.
val builder: AlertDialog.Builder = AlertDialog.Builder(ContextThemeWrapper(context, R.style.AlertDialogTheme))
Use the default layout or add a custom by builder.setView(R.layout.my_dialog)
In your styles:
<style name="AlertDialogTheme" parent="Theme.MaterialComponents.Light.Dialog.Alert">
<item name="buttonBarPositiveButtonStyle">#style/Alert.Button.Positive</item>
<item name="buttonBarNegativeButtonStyle">#style/Alert.Button.Neutral</item>
<item name="buttonBarNeutralButtonStyle">#style/Alert.Button.Neutral</item>
</style>
<style name="Alert.Button.Positive" parent="Widget.MaterialComponents.Button.TextButton">
<item name="backgroundTint">#color/transparent</item>
<item name="rippleColor">#color/colorAccent</item>
<item name="android:textColor">#color/colorPrimary</item>
<item name="android:textSize">14sp</item>
<item name="android:textAllCaps">false</item>
</style>
<style name="Alert.Button.Neutral" parent="Widget.MaterialComponents.Button.TextButton">
<item name="backgroundTint">#color/transparent</item>
<item name="rippleColor">#color/colorAccent</item>
<item name="android:textColor">#color/gray_dark</item>
<item name="android:textSize">14sp</item>
</style>

If you are using the Material Components library the best way to have an AlertDialog is to use the MaterialAlertDialogBuilder.
new MaterialAlertDialogBuilder(context)
.setTitle("Dialog")
.setMessage("Lorem ipsum dolor ....")
.setPositiveButton("Ok", /* listener = */ null)
.setNegativeButton("Cancel", /* listener = */ null)
.show();
It is the default result:
If you want also to apply a different style or color to the buttons you can check this answer.

I tested the above answers. Although I got a good idea, none worked for my case. So, this is my answer.
Make sure to have android:theme="#style/AppMaterialTheme" in your manifest file under Application or Activity.
Open your Styles.xml file and change it based on the following.
<style name="AppMaterialTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar">
<item name="colorPrimary">#color/primaryBlue</item>
<item name="colorPrimaryDark">#color/primaryBlue</item>
<item name="colorAccent">#color/colorAccent</item>
<item name="colorControlActivated">#color/primaryBlue</item>
<item name="colorControlHighlight">#color/colorAccent_main</item>
<item name="colorButtonNormal">#color/white</item>
<item name="materialAlertDialogTheme">#style/AlertDialogMaterialTheme</item>
</style>
<style name="AlertDialogMaterialTheme" parent="ThemeOverlay.MaterialComponents.MaterialAlertDialog">
<item name="buttonBarPositiveButtonStyle">#style/Alert.Button.Positive</item>
<item name="buttonBarNegativeButtonStyle">#style/Alert.Button.Negative</item>
</style>
<style name="Alert.Button.Positive" parent="Widget.MaterialComponents.Button.UnelevatedButton">
<item name="android:fillColor">#color/color_0054BB</item>
<item name="android:textColor">#color/white</item>
<item name="android:textAllCaps">false</item>
<item name="android:textSize">14sp</item>
<item name="rippleColor">#color/colorAccent_main</item>
</style>
<style name="Alert.Button.Negative" parent="Widget.MaterialComponents.Button.OutlinedButton">
<item name="strokeColor">#color/color_0054BB</item>
<item name="android:textColor">#color/color_0054BB</item>
<item name="android:textAllCaps">false</item>
<item name="android:textSize">14sp</item>
<item name="android:layout_marginEnd">8dp</item>
<item name="rippleColor">#color/colorAccent_main</item>
</style>
You won't need to apply the theme to your AlertDialog as your Activity applies the theme to it. So, create the dialog normally.
The result will be.

First, it's better to use use MaterialAlertDialog if you are using Material Theme.
You can read more here – Material.io → Theming dialogs
MaterialAlertDialogBuilder(context)
.setTitle(R.string.confirm)
.setMessage(R.string.logout)
.setPositiveButton(R.string.logout_alert_positive) { _, _ -> activity?.logout() }
.setNegativeButton(R.string.never_mind, null)
.show()
This is the layout.xml of the MaterialAlertDialog actions. As you can see there are 3 buttons and each has their own styles. So, here is how you can change them.
Step 1: Tell Android that you want to alter the default MaterialAlertDialog theme.
<style name="Base.AppTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar">
...
<item name="materialAlertDialogTheme">#style/AlertDialog</item>
...
</style>
Step 2: Tell Android that you want to alter a specific button style. buttonBarNeutralButtonStyle, buttonBarNegativeButtonStyle or buttonBarPositiveButtonStyle
<style name="AlertDialog" parent="ThemeOverlay.MaterialComponents.MaterialAlertDialog">
<item name="buttonBarNegativeButtonStyle">#style/NegativeButtonStyle</item>
</style>
Step 3: Define your custom style
<style name="NegativeButtonStyle" parent="Widget.MaterialComponents.Button.TextButton">
<item name="android:textColor">#FF0000</item>
</style>

Found another solution for this with using MaterialComponents here: https://issuetracker.google.com/issues/116861837#comment9
<style name="Theme.Custom.Material.Alert.Dialog.Light" parent="Theme.MaterialComponents.Light.Dialog.Alert">
<item name="materialButtonStyle">#style/Widget.AppCompat.Button.Borderless</item>
</style>
<style name="Theme.Custom.Material.Base.Light" parent="Theme.MaterialComponents.Light.NoActionBar">
<item name="android:dialogTheme">#style/Theme.Custom.Material.Alert.Dialog.Light</item>
<item name="android:alertDialogTheme">#style/Theme.Custom.Material.Alert.Dialog.Light</item>
....
</style>
Though it is still not "intended behavior" to me.

If you don't want to use androidx.appcompat.app.AlertDialog, you can just redefine the style of the dialog buttons:
In your style.xml :
<style name="AppTheme" parent="Theme.MaterialComponents.Light.NoActionBar">
...
<item name="android:buttonBarButtonStyle">#style/DialogButton</item>
...
</style>
<style name="DialogButton" parent="Widget.MaterialComponents.Button.TextButton"/>

If you are using the com.android.support:design:28.0.0 library, using android.support.v7.app.AlertDialog works as expected.

Theme.MaterialComponents does not change font of dialog title

I am using the material components theming for our app. Now we want a custom font, which I managed to apply almost everywhere with the theme below, which uses the various textAppearance... attributes defined by material components.
This works very well, and the theme is also applied to the AlertDialogs almost everywhere -- message text and buttons have the custom font, buttons have the correct accent colors etc.
Only the dialog title keeps the Roboto font, no matter what.
<!-- externalized font name for easier change -->
<string name="font_regular" translatable="false" tools:ignore="ReferenceType">#font/atma_regular</string>
<style name="Theme.App" parent="Theme.MaterialComponents.Light.NoActionBar">
<item name="colorPrimary">#color/colorPrimary</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorAccent">#color/colorAccent</item>
<item name="android:textColorPrimary">#color/textColorPrimary</item>
<item name="android:textColorSecondary">#color/textColorSecondary</item>
<item name="textAppearanceHeadline1">#style/TextAppearance.App.Button</item>
<item name="textAppearanceHeadline2">#style/TextAppearance.App.Button</item>
<item name="textAppearanceHeadline3">#style/TextAppearance.App.Button</item>
<item name="textAppearanceHeadline4">#style/TextAppearance.App.Button</item>
<item name="textAppearanceHeadline5">#style/TextAppearance.App.Button</item>
<item name="textAppearanceHeadline6">#style/TextAppearance.App.Button</item>
<item name="textAppearanceSubtitle1">#style/TextAppearance.App.Subtitle1</item>
<item name="textAppearanceSubtitle2">#style/TextAppearance.App.Subtitle2</item>
<item name="textAppearanceBody1">#style/TextAppearance.App.Body1</item>
<item name="textAppearanceBody2">#style/TextAppearance.App.Body2</item>
<item name="textAppearanceButton">#style/TextAppearance.App.Button</item>
<item name="android:textAppearanceLarge">#style/TextAppearance.App.Large</item>
<item name="android:textAppearanceMedium">#style/TextAppearance.App.Medium</item>
<item name="android:textAppearanceSmall">#style/TextAppearance.App.Small</item>
</style>
<style name="TextAppearance.App.Subtitle1" parent="TextAppearance.MaterialComponents.Subtitle1">
<item name="fontFamily">#string/font_regular</item>
<item name="android:fontFamily">#string/font_regular</item>
</style>
...
I tried to define an extra theme for the alert dialogs like so:
<style name="Theme.App" parent="Theme.MaterialComponents.Light.NoActionBar">
...
<item name="alertDialogTheme">#style/Theme.App.AlertDialog</item>
...
</style>
<style name="Theme.App.AlertDialog" parent="Theme.MaterialComponents.Light.Dialog.Alert">
<item name="android:windowTitleStyle">#style/TextAppearance.App.DialogWindowTitle</item>
</style>
<style name="TextAppearance.App.DialogWindowTitle" parent="ThemeOverlay.MaterialComponents.Dialog.Alert">
<item name="fontFamily">#string/font_regular</item>
<item name="android:fontFamily">#string/font_regular</item>
<item name="android:textSize">30sp</item>
</style>
But that resets the colors and fonts everywhere. The only thing that is applied, is the textSize.
It really shouldn't be so hard to achieve this, but I am out of ideas right now. I could apply the font programmatically, but that would be quite ugly.

As you mentioned the AlertDialog created by MaterialAlertDialogBuilder uses the style defined by the textAppearanceSubtitle1 attribute in your app theme.
Otherwise you can change the style used by the AlertDialog using something like:
new MaterialAlertDialogBuilder(MainActivity.this,
R.style.MyTitle_ThemeOverlay_MaterialComponents_MaterialAlertDialog)
.setTitle("Title")
.setMessage("Message......")
.setPositiveButton("ok", null)
.setNegativeButton("Cancel", null)
.show();
In your style you have to customize the materialAlertDialogTitleTextStyle attribute:
<style name="MyTitle_ThemeOverlay.MaterialComponents.MaterialAlertDialog" parent="#style/ThemeOverlay.MaterialComponents.MaterialAlertDialog">
<item name="materialAlertDialogTitleTextStyle">#style/MyTitle_MaterialAlertDialog.MaterialComponents.Title.Text</item>
</style>
<style name="MyTitle_MaterialAlertDialog.MaterialComponents.Title.Text" parent="#style/MaterialAlertDialog.MaterialComponents.Title.Text">
<item name="android:textAppearance">#style/MyTitle_TextAppearance.MaterialComponents.Subtitle1</item>
</style>
<style name="MyTitle_TextAppearance.MaterialComponents.Subtitle1" parent="TextAppearance.MaterialComponents.Subtitle1">
<item name="fontFamily">....</item>
<item name="android:fontFamily">....</item>
<item name="android:textStyle">.....</item>
</style>

Thanks to your question I realized that I was using the incorrect attribute to assign the title style (android:titleTextAppearance instead of android:windowTitleStyle).
It looks like your issue has been fixed in the meantime, as your exact code seems to work for me as of today.

AlertDialog styling - how to change style (color) of title, message, etc

I've breaking my head over this quite a bit. What I need to do is, change the style of all AlertDialogs in my android application - dialog background needs to be white-ish, and text needs to be black-ish. I tried creating a lot of styles, themes, and applying from the code, manifest, etc, but no success, with regard to the text colors inside the AlertDialog. Right now, I have the simplest of codes, set like this:
Manifest:
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
styles.xml:
<style name="AppTheme" parent="AppBaseTheme">
<item name="android:alertDialogStyle">#style/DialogStyle</item>
</style>
<style name="DialogStyle" parent="#android:style/Theme.Dialog">
<!-- changing these background stuff works fine -->
<item name="android:bottomBright">#android:color/white</item>
<item name="android:bottomDark">#android:color/white</item>
<item name="android:bottomMedium">#drawable/dialog_footer_bg</item>
<item name="android:centerBright">#android:color/white</item>
<item name="android:centerDark">#drawable/dialog_body_bg</item>
<item name="android:centerMedium">#android:color/white</item>
<item name="android:fullBright">#color/orange</item>
<item name="android:fullDark">#color/orange</item>
<item name="android:topBright">#color/green</item>
<item name="android:topDark">#drawable/dialog_header_bg</item>
The items listed below don't work (please read the comments I've put above each element):
<!-- panelBackground is not getting set to null, there is something squarish around it -->
<item name="android:panelBackground">#null</item>
<!-- Setting this textColor doesn't seem to have any effect at all. Messages, title, button text color, whatever; nothing changes. -->
<item name="android:textColor">#000000</item>
<!-- Also tried with textAppearance, as follows. Didn't work -->
<item name="android:textAppearance">?android:attr/textColorPrimaryInverse</item>
<!-- Also tried changing textAppearancePrimary, to no avail -->
<item name="android:textColorPrimary">#000000</item>
<!-- Also need to change the dialog title text, tried it as follows, dint work: -->
<item name="android:windowTitleStyle">#style/DialogWindowTitle</item>
</style>
The DialogWindowTitle is defined as follows:
<style name="DialogWindowTitle">
<item name="android:textAppearance">?android:attr/textAppearanceMediumInverse</item>
</style>
So none of these is working. Can anyone tell me what I could be doing wrong, and how can I:
Change text color for messages (content text)
Change title text color
Remove the
panel background
Note: I need to support API 8 (2.2) upwards. Also, I've went through most of the related question here, and google groups, but can't figure out, though I have a feeling its right under my nose!
Edit: adding screenshot:

You need to define a Theme for your AlertDialog and reference it in your Activity's theme. The attribute is alertDialogTheme and not alertDialogStyle. Like this:
<style name="Theme.YourTheme" parent="#android:style/Theme.Holo">
...
<item name="android:alertDialogTheme">#style/YourAlertDialogTheme</item>
</style>
<style name="YourAlertDialogTheme">
<item name="android:windowBackground">#android:color/transparent</item>
<item name="android:windowContentOverlay">#null</item>
<item name="android:windowIsFloating">true</item>
<item name="android:windowAnimationStyle">#android:style/Animation.Dialog</item>
<item name="android:windowMinWidthMajor">#android:dimen/dialog_min_width_major</item>
<item name="android:windowMinWidthMinor">#android:dimen/dialog_min_width_minor</item>
<item name="android:windowTitleStyle">...</item>
<item name="android:textAppearanceMedium">...</item>
<item name="android:borderlessButtonStyle">...</item>
<item name="android:buttonBarStyle">...</item>
</style>
You'll be able to change color and text appearance for the title, the message and you'll have some control on the background of each area. I wrote a blog post detailing the steps to style an AlertDialog.

Remove the panel background
<item name="android:windowBackground">#color/transparent_color</item>
<color name="transparent_color">#00000000</color>
This is Mystyle:
<style name="ThemeDialogCustom">
<item name="android:windowFrame">#null</item>
<item name="android:windowIsFloating">true</item>
<item name="android:windowContentOverlay">#null</item>
<item name="android:windowAnimationStyle">#android:style/Animation.Dialog</item>
<item name="android:windowBackground">#color/transparent_color</item>
<item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
<item name="android:colorBackgroundCacheHint">#null</item>
</style>
Which i have added to the constructor.
Add textColor :
<item name="android:textColor">#ff0000</item>

Here's my Code to theme the alert dialog box:
<style name="alertDialog" parent="Theme.AppCompat.Dialog.Alert">
<item name="android:background">#color/light_button_text_color</item>
<item name="android:textColor">#android:color/black</item>
<item name="android:textColorPrimary">#android:color/black</item>
<item name="android:textColorSecondary">#android:color/black</item>
<item name="android:titleTextColor" tools:targetApi="m">#android:color/black</item>
</style>
Place this code in styles.xml.
In your java apply this theme as:
AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.alertDialog);
Output of the code

You have to add the style to the constructor of the dialog
builder = new AlertDialog.Builder(this, R.style.DialogStyle);

I changed color programmatically in this way :
var builder = new AlertDialog.Builder (this);
...
...
...
var dialog = builder.Show ();
int textColorId = Resources.GetIdentifier ("alertTitle", "id", "android");
TextView textColor = dialog.FindViewById<TextView> (textColorId);
textColor?.SetTextColor (Color.DarkRed);
as alertTitle, you can change other data by this way (next example is for titleDivider):
int titleDividerId = Resources.GetIdentifier ("titleDivider", "id", "android");
View titleDivider = dialog.FindViewById (titleDividerId);
titleDivider?.SetBackgroundColor (Color.Red);
this is in C#, but in java it is the same.

It depends how much you want to customize the alert dialog. I have different steps in order to customize the alert dialog. Please visit: https://stackoverflow.com/a/33439849/5475941

Building on #general03's answer, you can use Android's built-in style to customize the dialog quickly. You can find the dialog themes under android.R.style.Theme_DeviceDefault_Dialogxxx.
For example:
builder = new AlertDialog.Builder(this, android.R.style.Theme_DeviceDefault_Dialog_MinWidth);
builder = new AlertDialog.Builder(this, android.R.style.Theme_DeviceDefault_Dialog_NoActionBar);
builder = new AlertDialog.Builder(this, android.R.style.Theme_DeviceDefault_DialogWhenLarge);

Use this in your Style in your values-v21/style.xml
<style name="AlertDialogCustom" parent="#android:style/Theme.Material.Dialog.NoActionBar">
<item name="android:windowBackground">#android:color/white</item>
<item name="android:windowActionBar">false</item>
<item name="android:colorAccent">#color/cbt_ui_primary_dark</item>
<item name="android:windowTitleStyle">#style/DialogWindowTitle.Sphinx</item>
<item name="android:textColorPrimary">#color/cbt_hints_color</item>
<item name="android:backgroundDimEnabled">true</item>
<item name="android:windowMinWidthMajor">#android:dimen/dialog_min_width_major</item>
<item name="android:windowMinWidthMinor">#android:dimen/dialog_min_width_minor</item>
</style>
And for pre lollipop devices put it in values/style.xml
<style name="AlertDialogCustom" parent="#android:style/Theme.Material.Dialog.NoActionBar">
<item name="android:windowBackground">#android:color/white</item>
<item name="android:windowActionBar">false</item>
<item name="android:colorAccent">#color/cbt_ui_primary_dark</item>
<item name="android:windowTitleStyle">#style/DialogWindowTitle.Sphinx</item>
<item name="android:textColorPrimary">#color/cbt_hints_color</item>
<item name="android:backgroundDimEnabled">true</item>
<item name="android:windowMinWidthMajor">#android:dimen/dialog_min_width_major</item>
<item name="android:windowMinWidthMinor">#android:dimen/dialog_min_width_minor</item>
</style>
<style name="DialogWindowTitle.Sphinx" parent="#style/DialogWindowTitle_Holo">
<item name="android:textAppearance">#style/TextAppearance.Sphinx.DialogWindowTitle</item>
</style>
<style name="TextAppearance.Sphinx.DialogWindowTitle" parent="#android:style/TextAppearance.Holo.DialogWindowTitle">
<item name="android:textColor">#color/dark</item>
<!--<item name="android:fontFamily">sans-serif-condensed</item>-->
<item name="android:textStyle">bold</item>
</style>

Android - change dialog title style of all dialogs in application

Is there a way I can change all the alert dialogs appearing in my Android application? I want to change the dialogs that are system generated as well (like the Edit Text dialog that opens up when you long tap on any EditText). I want to change the title font color and size of all the dialogs in my app.
Is there a way to do it?
I have tried setting android:alertDialogTheme in my theme. But it seems to be not working. Code following -
<style name="Theme.DLight" parent="android:Theme.Light.NoTitleBar">
<item name="android:alertDialogTheme">#style/DialogStyle</item>
</style>
and
<style name="DialogStyle" parent="android:Theme" >
<item name="android:windowBackground">#drawable/background_holo_light</item>
<item name="android:textColor">#014076</item>
</style>
EDIT
I'm not invoking a dialog from my code. It's just the default dialog
that appears when you long click on any EditText. Generally it
contains the keyboard options like Select word, Select all, Input
method etc.

In you dialog theme, the attribute you need to modify windowTitleStyle. There, reference a style for your title and define a text appearance for this title. For example, to display your title red and bold:
<style name="AppTheme" parent="#android:style/Theme.Holo">
...
<item name="alertDialogTheme">#style/AppTheme.AlertDialog</item>
</style>
<style name="DialogStyle" parent="#style/Theme.Holo.Dialog.Alert">
...
<item name="android:windowTitleStyle">#style/DialogWindowTitle_Custom</item>
</style>
<style name="DialogWindowTitle_Custom" parent="#style/DialogWindowTitle_Holo">
<item name="android:maxLines">1</item>
<item name="android:scrollHorizontally">true</item>
<item name="android:textAppearance">#style/TextAppearance_DialogWindowTitle</item>
</style>
<style name="TextAppearance_DialogWindowTitle" parent="#android:style/TextAppearance.Holo.DialogWindowTitle">
<item name="android:textColor">#android:color/holo_red_light</item>
<item name="android:textStyle">bold</item>
</style>
If you want to style a little bit more your AlertDialog, I wrote a blog post detailing the steps.

In styles.xml:
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
//All your other styles and add the one mntioned below.
<item name="alertDialogTheme">#style/AlertDialogStyle</item>
</style>
In the styles of AlertDialog add:
<style name="AlertDialogStyle" parent="Theme.AppCompat.Light.Dialog.Alert">
<item name="colorAccent">#color/colorAccent</item>
<item name="android:textColorPrimary">#color/primary_text</item>
<item name="android:editTextColor">#color/primary_text</item>
<item name="android:background">#color/white</item>
<item name="android:windowTitleStyle">#style/TextAppearance.AppCompat.Title</item>
</style>
windowTitleStyle is important to add as it will give your title that effect that you need.
Now simply use this Theme in your AlertDialog in any activity that you want like below:
AlertDialog.Builder dialog = new AlertDialog.Builder(this, R.style.AlertDialogStyle);