Develop Reference

Material design: Where to place elevation in android styles?

I want to set item elevation in some of my app's styles. Now elevation is only 21 and higher with no support library, so my natural inclination was to just create a styles-v21 xml and place it in there:
<style name="Widget.MyApp.Drawer" parent="ThemeOverlay.AppCompat.Dark.ActionBar">
<item name="android:elevation">4dp</item>
</style>
The problem with this is any changes I make to Widget.MyApp.Drawer in the regular styles.xml file will be overwritten by this completely. What I'd want is for elevation to just be tacked on to the bottom of the list of style changes I made for the v21 version of this style listed in styles.xml.
So I took to creating base styles which the style I use in the views inherits from:
<style name="BaseListElement">
<item name="android:background">#drawable/listitem_background</item>
<item name="android:layout_height">#dimen/list_item_height</item>
</style>
<style name="BaseListElement.ListItem">
</style>
I leave the style blank in styles.xml, and in styles-v21, I add elevation and it works.
However this get's kind of tricky when I want to use some advanced styles:
<style name="BaseListElement">
<item name="android:background">#drawable/listitem_background</item>
<item name="android:layout_height">#dimen/list_item_height</item>
</style>
<style name="BaseListElement.BaseItem">
<item name="android:padding">#dimen/list_item_padding</item>
</style>
<style name="Widget.MyApp.ListItem" parent="#style/BaseListElement.BaseItem">
</style>
<style name="BaseListElement.BaseHeader">
</style>
In this case, BaseItem is just one style that inherits from BaseListElement, styles such as BaseHeader inherit from it as well. This is getting kind of ridiculous as you can see.
Am I overthinking this? The way I see it I have 3 choices here:
1) Continue as is and feel like an idiot
2) On the BaseListElement level, create a child style with some goofy name which is the point at which I apply the elevation, which would then (hopefully) trickle down to all the children. As soon as I have a difference between v21 children of the base however, this wouldn't work.
3) Just throw android:elevation into the styles.xml file (don't use a v21 file) and place an ignore flag on the element. I only have 5.0 devices here, so I can't easily test at the moment if this will cause a crash on older versions.
Any thoughts?

To accomplish something like this you could just create a BaseListElement.BaseItem in both styles.xml and syles-v21.xml the first one without the elevation and the second one with it. Then just extend Widget.MyApp.ListItem from BaseListElement.BaseItem which should get updated in v21 to use the elevation.
styles.xml
<style name="BaseListElement.BaseItem">
</style>
<style name="Widget.MyApp.ListItem" parent="#style/BaseListElement.BaseItem">
</style>
styles-v21.xml
<style name="BaseListElement.BaseItem">
<item name="android:padding">#dimen/list_item_padding</item>
</style>
Method 3 you can safely implement as follows:
<item name="android:elevation" tools:ignore="NewApi">4dp</item>

Set a consistent theme for all the editTexts in Android

I have finished making my app. Now, I want to reset all my editTexts to have the layout width as fill parent instead of wrap content.
android:layout_width="fill_parent"
while currently all my editTexts are
android:layout_width="wrap_content"
Is there any way i can do this in a style xml file, instead of individually in each layout?
I currently have this as my styles.xml
<style name="AppTheme" parent="android:Theme.Light">
<item name="android:fontFamily">Verdana</item>
<item name="android:editTextStyle">#style/EditTextStyle</item>
</style>
<style name="EditTextStyle" parent="#android:style/Widget.EditText">
<item name="android:layout_width">fill_parent</item>
<item name="android:textColor">#808080</item>
</style>
But i'm getting an exception saying that layout_width must be specified.
This is my exception:
07-15 11:13:34.872: E/AndroidRuntime(1195): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.passwordkeeper.ui/com.passwordkeeper.ui.ActivityLogin}: java.lang.RuntimeException: Binary XML file line #29: You must supply a layout_width attribute.
Any easy way out or do i have to change the attribute in all my editText's individually?

You can try this one.
Here is the part of the manifest file you need to change to call your custom theme (the custom theme called here is AppTheme:
<application android:name="YourApplication"
android:theme="#style/AppTheme" >
Then in your file styles.xml, create and customize this custom theme:
<style name="AppTheme" parent="#android:style/Theme.Holo.Light">
<item name="android:typeface">YourTypeFace</item>
</style>
You can add the parameters you need inside the style. This will apply the style to all your textviews.

One solution to your problem is to apply a custom theme to all of your activities. In order to do that, you can inherit properties from an existing theme and override the properties that you want to change.
In AndroidManifest.xml, locate the <application> element.
Add the attribute to it:
android:theme="#style/"
Locate styles.xml file in the values folder.
Use the following template:
<style name="ApplicationStyle" parent="android:Theme.Light">
<item name="#android:editTextStyle">#style/customEditText</item>"
</style>
Names used in the above are just examples, you may use your own. As to the parent theme, that is also up to you.
All that is left is the definition of editTextStyle (or whatever name you have chosen for the style). You should inherit properties from Widget.EditText and override the properties that you want to change, like the following:
<style name="customEditText" parent="#android:style/Widget.EditText">
<item name="android:textColor" >#ffffff</item>
</style>
To quote the official android guide:
The parent attribute in the element is optional and specifies
the resource ID of another style from which this style should inherit
properties. You can then override the inherited style properties if
you want to.
I tried to make it easy to understand and follow. I'm a junior dev so while the above solution works for me, it may not be the best one out there. As I said though, it solves the problem rather efficiently.

Unfortunately it is not possible to set layout attributes (layout_*) from a theme (see Layout Parameters documentation and this answer from an Android framework engineer). You must set them on each element or set the layout attributes in a style and let each element reference the style like this:
<Button style="#style/ButtonBig" android:text="my text" />
where ButtonBig is defined like this:
<style name="ButtonBig" parent="android:Widget.Holo.Light.Button">
<item name="android:textSize">20sp</item>
<item name="android:layout_width">match_parent</item>
<item name="android:layout_height">100dp</item>
</style>

I was having this exact issue. For some reason it helped me to drop the android: part in the AppTheme definition, and leave it only as editTextStyle (as mentioned in this answer):
<style name="AppTheme" parent="android:Theme.Light">
<item name="android:fontFamily">Verdana</item>
<item name="editTextStyle">#style/EditTextStyle</item>
</style>

You'll have to set the property style="#styles/EditTextStyle" to all of your EditText components in your application.

define the style attribute for all EditText like below:
<EditText
android:id="#+id/editText1"
android:layout_height="wrap_content"
style="#style/EditTextStyle">

You have to specify layout_width individually to each and every View. There is no way To escape. You can create a LayoutParams object and set its width and height in it and set in it every EditText like
textView1.setLayoutParams(lParams);
textView2.setLayoutParams(lParams);
...

Modify existing theme

I would like to know if it is possible (and how) to customize an existing theme.
What I'm looking for is how can I retrieve a certain attribute (i.e. color) and change it when the Activity starts and reapply the modified theme before setContentView().
Similar to setTheme(), but instead of using a resource id, use the modified theme.

Why not just make your own theme, setting the android:parent to the theme you want to copy, then set your own attributes? That is demonstrated in this documentation, like so:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="CodeFont" parent="#android:style/TextAppearance.Medium">
<item name="android:layout_width">fill_parent</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:textColor">#00FF00</item>
<item name="android:typeface">monospace</item>
</style>
</resources>
In this case, the CodeFont style will be identical to the TextAppearance.Medium style, except for the items specified here. You can do the same with any theme, including the default Holo or Dark theme or whatnot.

Based on further research and Eric's comment there is not yet a possible way to modify a theme programmatically. Different themes can be applied programmatically but not modified. Once the style is set in XML, it cannot be modified.

android set custom backgorund color to wintow title of Theme.Holo.Light themed applicatin

I am trying to set custom background colour to title of Theme.Holo.Light application with below xml. But it doesn't work.
Theme.Holo.Light somehow overrides #style/WindowTitleBackground
if I set parent to just android:Theme, it works fine. I want to ave Halo.Light theme but with different background. I have seen custom background layout samples but as I am learning I don't want to go in to that.
Any help appreciated.
Thanks
<style name="theme" parent="android:Theme.Holo.Light">
<item name="android:windowNoTitle">false</item>
<item name="android:windowTitleBackgroundStyle">#style/WindowTitleBackground</item>
</style>
<style name="WindowTitleBackground">
<item name="android:background">#000000</item>
</style>

when you use android:background, it must be drawable resource, so using value such as #ff234562 directly will not be valid,in fact you should define the value in colors.xml first,then use like this
<item name="android:background">#color/green</item>

It seems like Android uses bitmaps for that value (either #null or #android:drawable/title_bar).
Try creating a black png and use it instead of the color code:
<style name="WindowTitleBackground">
<item name="android:background">#drawable/black</item>
</style>

How to apply two different styles to one element in android?

I have a TextView and I want to apply a Style which I use for all TextView elements plus another style which I only use within a specific Activity. Is there any possibility to do that?

Just a little piece of information that might add to the overall value of the question - shamelessly copied from: http://developer.android.com/guide/topics/ui/themes.html#DefiningStyles
If you want to inherit from styles that you've defined yourself, you do not have to use the parent attribute. Instead, just prefix the name of the style you want to inherit to the name of your new style, separated by a period. For example, to create a new style that inherits the CodeFont style defined above, but make the color red, you can author the new style like this:
<style name="CodeFont.Red">
<item name="android:textColor">#FF0000</item>
</style>
Notice that there is no parent attribute in the tag, but because the name attribute begins with the CodeFont style name (which is a style that you have created), this style inherits all style properties from that style. This style then overrides the android:textColor property to make the text red. You can reference this new style as #style/CodeFont.Red.
You can continue inheriting like this as many times as you'd like, by chaining names with periods. For example, you can extend CodeFont.Red to be bigger, with:
<style name="CodeFont.Red.Big">
<item name="android:textSize">30sp</item>
</style>

A style under Android can have a parent style.
So just have MyActivityTextView define GeneralTextView as parent style, and change/add style properties.
Then you can use MyActivityTextView for some views and GeneralTextView for the others.
It's described in Defining Styles.

You can extend one style with another in your style.xml:
<style name="current_weekday_white" parent="current_day_white">
<item name="android:textColor">#FFABAB</item>
</style>

Inherit one style from another and copy elements from third.
<style name="Button.Style1" parent="android:style/Widget.Button">
<item name="android:gravity">center</item>
<item name="android:textSize">12sp</item>
<item name="android:background">#drawable/shape_button</item>
<!-- Here are attributes from third style -->
<item name="android:fontFamily">sans-serif-medium</item>
<item name="android:textColor">#112233</item>
</style>