Develop Reference

The night/theme.xml in android studio

The "colorprimary" changes in themes.xml then the button colour also changes "(image in lite mode)enter image description here (image in dark mode)enter image description hereedittext hint selection colour also changes . I want to edit text colour with out changing the theme and without changing button colour

I think, is important to mention first that a theme is different than a style. Basically, when you apply a style it only affects to the component( edit text, view, textview, etc). But when you apply a theme it affects in general terms to the app. More info about in this Link.
So, if you are applying a theme probably you are modifying some attributes that are being used in the app scope such as primaryColor, secondaryColor, etc. Probably, the editText is using primaryColor in order to set the color of the hint and when you change to another theme, primaryColor is affected, then the color hint of the editText is affected as well.
Based on the above description, we can apply multiple solutions. I would like to suggest the following.
default theme.xml
<style name="AppTheme" parent="AppTheme.Base" />
<style name="AppTheme.Base" parent="Theme.MaterialComponents.DayNight.NoActionBar">
<item name="colorPrimary">#color/gray_medium_dark</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorPrimaryVariant">#color/gray_dark</item>
<item name="colorSecondary">#color/cyan</item>
<item name="editTextStyle">#style/CustomEditTextStyle</item>
</style>
nigh theme theme.xml
<style name="AppTheme" parent="AppTheme.Base">
<item name="android:windowLightNavigationBar" tools:ignore="NewApi">false</item>
</style>
style.xml
<style name="CustomEditTextStyle" parent="Widget.AppCompat.EditText">
<item name="android:textSize">#dimen/text_size_16sp</item>
<item name="android:textColorHint">#color/gray_normal_light</item>
<item name="android:fontFamily">#font/roboto_condensed</item>
<item name="android:textColor">#color/colorPrimaryText</item>
<item name="android:inputType">textVisiblePassword</item>
</style>
Explanation: Another important point about style and themes is that we can apply something similar to inheritance. It means that we ca re-use some attributes or/and modify others.
So, <item name="editTextStyle">#style/CustomEditTextStyle</item> means that for all the edittext on my application I want to set up CustomEditTextStyle style. Also, in nigh theme we are applying parent as parent="AppTheme.Base" and this parent also has CustomEditTextStyle as style for edittext, so it will no change.

How to apply style to all Buttons but not to ImageButtons?

I need to apply a background color to all the buttons in my application, so I added this to styles.xml
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- button styles -->
<item name="colorButtonNormal">#color/button_color</item> <!-- below api 21 -->
<item name="android:colorButtonNormal">#color/button_color</item> <!-- above api 21 -->
<item name="android:buttonStyle">#style/ButtonColor</item>
</style>
<style name="ButtonColor" parent="#style/Widget.AppCompat.Button">
<item name="android:textColor">#color/font</item>
</style>
It worked perfectly, when I add a button in XML, the button has automatically the colors I set in styles.xml
The problem is that when I add a ImageButton, the ImageButton is getting also those colors, and I don't want that. The problem is specifically with colorButtonNormal, which applyes the background color to the ImageButton also and I don't want that. How can I solve this problem?

The default style used by the ImageButton (in your case AppCompatImageButton) is defined in the app theme by the attr:
<item name="imageButtonStyle">#style/Widget.AppCompat.ImageButton</item>
In this style the background attribute <item name="background">#drawable/btn_default_material</item> is tinted with the android:tint="?attr/colorButtonNormal".
You can use a custom style starting from btn_default_material for the ImageButton or you can override the color in the layout.
Something like:
<ImageButton
android:theme="#style/MyImageButtonTheme"/>
with something like:
<style name="MyImageButtonTheme" parent="ThemeOverlay.AppCompat.Light">
<item name="colorButtonNormal">#color/my_color</item>
</style>
Also evaluate to migrate to Material Components and the MaterialButton.
In this case it is very simple to override the color just using the styles:
<style name="MyButtonTheme" parent="Widget.MaterialComponents.Button">
<item name="materialThemeOverlay">#style/ButtonStylePrimaryColor</item>
</style>
<style name="ButtonStylePrimaryColor">
<item name="colorPrimary">#color/....</item>
</style>

You can do it by applying different style for defferent views
Let's say i have three style with defferent color combination and i wish to apply bigButtonTheme style for all big button
Then
i add this line on all big button android:theme="#style/bigButtonTheme">
Rest button or other vewis will remain unchanged.
You can also copy other properties of a style like global themes font background color by deffineing as parents theme
<style name="ButtonColor" parent="#style/GlobelStyleOfApp"/>

Android App - Theme fully works when applied to individual button, but only partially when applied globally

I'm using Android Studio with min API level 23 and targeting API 28.
I defined a theme in styles.xml as follows. Colors are all valid and present.
<style name="GreatButton" parent="Widget.AppCompat.Button.Colored">
<item name="colorButtonNormal">#color/orange_900</item>
<item name="colorAccent">#color/blue_900</item>
<item name="android:textColor">#color/white</item>
</style>
I have this theme as a global for all Buttons with buttonStyle (tried android:buttonStyle too)
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">#color/colorPrimary</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorAccent">#color/colorAccent</item>
<item name="buttonStyle">#style/GreatButton</item>
</style>
I have three buttons in my Activity (which inherits from AppCompatActivity).
Of these only one button has the theme explicitly specified
android:theme="#style/GreatButton"
This is how the buttons render
As you can see, the theme fully applied to the first button- one for which I specifically applied it (blue background and white text).
The same theme partially applied (white text) to the other buttons and for background color, it defaulted to the default behavior for coloredButton which is to have background for enabled buttons to be of #color/colorAccent (pink in my case)
So why does the global button theme apply only partially (just text color) when obviously the syntax is right (as can be evidenced from the theme applying correctly when explicitly specified for a button)?
Edit: This is not a duplicate as noted in comments

Google IO 2016 App's status bar

How the change status bar icon's color change in like Google IO 2016 App? I know there is no method. It looks like inverted.
EDIT
I finally find from a old post, it can be only grey if you are api 23 or above using:
<item name="android:windowLightStatusBar">true</item>

Use the material theme and change the colors to get the theme you want.

well in your values-v21/styles.xml you can change the color and theme to whatever you want
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light">
<item name="colorPrimary">#color/color_primary</item>
<item name="colorPrimaryDark">#color/color_secondary</item>
<item name="colorAccent">#color/color_accent</item>
<item name="android:statusBarColor">#color/color_primary</item>
</style>
</resources>
Update:
In Marshmallow you can achieve dark icons with light status bar with android:windowLightStatusBar attribute, e.g in your values-v23/styles.xml you can set
<item name="android:windowLightStatusBar">true</item>

Android, SherlockActionBar: change text color

I want to change the color of text in my actionBar (from black to white), but it seems like nothing's working... somebody has suggestions?

Use custom style (If you are using Actionbarsherlock)
<style name="Widget.Styled.ActionBar" parent="Widget.Sherlock.Light.ActionBar.Solid.Inverse">
<item name="titleTextStyle">#style/TitleText</item>
<item name="android:titleTextStyle">#style/TitleText</item>
</style>
<style name="TitleText">
<item name="android:textColor">#android:color/white</item>
<item name="android:textSize">17dip</item>
</style>
in the themes.xml file.
Edit
to apply the theme
<style name="Theme.Custom" parent="Theme.Sherlock.Light">
<item name="actionBarStyle">#style/Widget.Styled.ActionBar</item>
<item name="android:actionBarStyle">#style/Widget.Styled.ActionBar</item>
</style>
and in your activity/application in manifest
android:theme="#style/Theme.Custom"

probably the easiest way to style the action bar is using the action bar style generator online tool, you can find it here: http://jgilfelt.github.io/android-actionbarstylegenerator .
It will take care of generating all the needed assets and styles.
To have the text white, you can simply select "Dark" or "Light - Dark Actionbar" as base theme, then change the other colors according to your needs.