Develop Reference

Change the actionbar homeAsUpIndicator Programmatically

I used the following hack to change the homeAsupIndicator programmatically.
int upId = Resources.getSystem().getIdentifier("up", "id", "android");
if (upId > 0) {
ImageView up = (ImageView) findViewById(upId);
up.setImageResource(R.drawable.ic_action_bar_menu);
up.setPadding(0, 0, 20, 0);
}
But this is not working on most new phones (HTC One, Galaxy S3, etc). Is there a way that can be changed uniformly across devices. I need it to be changed only on home screen. Other screens would have the default one. So cannot use the styles.xml

This is what i did to acheive the behavior. I inherited the base theme and created a new theme to use it as a theme for the specific activity.
<style name="CustomActivityTheme" parent="AppTheme">
<item name="android:homeAsUpIndicator">#drawable/custom_home_as_up_icon</item>
</style>
and in the android manifest i made the activity theme as the above.
<activity
android:name="com.example.CustomActivity"
android:theme="#style/CustomActivityTheme" >
</activity>
works great. Will update again when i check on all devices I have. Thanks #faylon for pointing in the right direction

The question was to change dynamically the Up Home Indicator, although this answer was accepting and it is about Themes and Styles. I found a way to do this programmatically, according to Adneal's answer which gives me the clue and specially the right way to do. I used the below snippet code and it works well on (tested) devices with APIs mentioned here.
For lower APIs, I use R.id.up which is not available on higher API. That's why, I retrieve this id by a little workaround which is getting the parent of home button (android.R.id.home) and its first child (android.R.id.up):
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
// get the parent view of home (app icon) imageview
ViewGroup home = (ViewGroup) findViewById(android.R.id.home).getParent();
// get the first child (up imageview)
( (ImageView) home.getChildAt(0) )
// change the icon according to your needs
.setImageResource(R.drawable.custom_icon_up));
} else {
// get the up imageview directly with R.id.up
( (ImageView) findViewById(R.id.up) )
.setImageResource(R.drawable.custom_icon_up));
}
Note: If you don't use the SDK condition, you will get some NullPointerException.

API 18 has new methods ActionBar.setHomeAsUpIndicator() - unfortunately these aren't supported in the support library at this moment
http://developer.android.com/reference/android/app/ActionBar.html#setHomeAsUpIndicator(android.graphics.drawable.Drawable)
edit: these are now supported by the support library
http://developer.android.com/reference/android/support/v7/app/ActionBar.html#setHomeAsUpIndicator(android.graphics.drawable.Drawable)

All you need to do is to use this line of code:
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
This will change the icon with the up indicator. To disable it later, just call this function again and pass false as the param.

The solution by checking Resources.getSystem() doesn't work on all devices, A better solution to change the homeAsUpIndicator is to set it #null in style and change the logo resource programmatically.
Below is my code from style.xml
<style name="Theme.HomeScreen" parent="AppBaseTheme">
<item name="displayOptions">showHome|useLogo</item>
<item name="homeAsUpIndicator">#null</item>
<item name="android:homeAsUpIndicator">#null</item>
</style>
In code you can change the logo using setLogo() method.
getSupportActionBar().setLogo(R.drawable.abc_ic_ab_back_holo_light); //for ActionBarCompat
getActionBar().setLogo(R.drawable.abc_ic_ab_back_holo_light); //for default actionbar for post 3.0 devices
Also note that the Android API 18 has methods to edit the homeAsUpIndicator programatically, refer documentation.

You can achieve this in an easier way. Try to can change the homeAsUpIndicator attribute of actionBarStyle in your theme.xml and styles.xml.
If you want some padding, just add some white space in your image.

You can try this:
this.getSupportActionBar().setHomeAsUpIndicator( R.drawable.actionbar_indicator ); //for ActionBarCompat
this.getActionBar().setHomeAsUpIndicator( R.drawable.actionbar_indicator ); //for default actionbar for post 3.0 devices
If you need change the position of the icon, you must create a drawable file containing a "layer-list" like this:
actionbar_indicator.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list
xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:drawable="#drawable/indicator"
android:right="5dp"
android:left="10dp" />
</layer-list>

use getActionBar().setCustomView(int yourView); because ActionBar haven't method to change homeUp icon!

Adding to Fllo answer Change the actionbar homeAsUpIndicator Programamtically
I was able to use this hack on Android 4+ but could not understand why the up/home indicator was back to the default one when search widget was expanded. Looking at the view hierarchy, turns out that the up/home indicator + icon section of the action bar has 2 implementations and of course the first on is the one for when the search widget is not expanded. So here is the code I used to work around this and get the up/home indicator changed in both cases.
mSearchItem.setOnActionExpandListener(new MenuItem.OnActionExpandListener() {
#Override
public boolean onMenuItemActionExpand(MenuItem item) {
// https://stackoverflow.com/questions/17585892/change-the-actionbar-homeasupindicator-programamtically
int actionBarId = getResources().getIdentifier("android:id/action_bar", null, null);
View view = getActivity().getWindow().getDecorView().findViewById(actionBarId);
if (view == null
|| !(view instanceof ViewGroup)) {
return true;
}
final ViewGroup actionBarView = (ViewGroup)view;
// The second home view is only inflated after
// setOnActionExpandListener() is first called
actionBarView.post(new Runnable() {
#Override
public void run() {
//The 2 ActionBarView$HomeView views are always children of the same view group
//However, they are not always children of the ActionBarView itself
//(depends on OS version)
int upId = getResources().getIdentifier("android:id/up", null, null);
View upView = actionBarView.findViewById(upId);
ViewParent viewParent = upView.getParent();
if (viewParent == null) {
return;
}
viewParent = viewParent.getParent();
if (viewParent == null
|| !(viewParent instanceof ViewGroup)) {
return;
}
ViewGroup viewGroup = (ViewGroup) viewParent;
int childCount = viewGroup.getChildCount();
for (int i = 0; i < childCount; i++) {
View childView = viewGroup.getChildAt(i);
if (childView instanceof ViewGroup) {
ViewGroup homeView = (ViewGroup) childView;
upView = homeView.findViewById(upId);
if (upView != null
&& upView instanceof ImageView) {
Drawable upDrawable = getResources().getDrawable(R.drawable.ic_ab_back_holo_dark_am);
upDrawable.setColorFilter(accentColorInt, PorterDuff.Mode.MULTIPLY);
((ImageView) upView).setImageDrawable(upDrawable);
}
}
}
}
});

If someone uses the library support-v7 appcompat, you can directly call this method:
getSupportActionBar().setHomeAsUpIndicator(int redId)
In other case you can use this solution:
https://stackoverflow.com/a/23522910/944630

If you are using DrawerLayout with ActionBarDrawerToggle, then check out this answer.

this.getSupportActionBar().setDisplayUseLogoEnabled(true);
this.getSupportActionBar().setLogo(R.drawable.about_selected);
Also you can define the logo in manifest in attribute android:logo of and tags and set in theme that you want to use logo instead of app icon in the action bar.

How to change home as up resource programmatically?

I know how to change the homeAsUpIndicator in the styles xml file. The question is how to change it programmatically.
The reason I want to do it because in some views I support side navigation (sliding menu) - pressing the up/back title button, shows the side menu.
In other views I support the natural up/back botton.
Thus I would like to different indicator icons to indicate the two different logics - side navigation vs. up/back.
Please, lets not argue on the motivation of doing this. That's the given state. Thanks.

int upId = Resources.getSystem().getIdentifier("up", "id", "android");
if (upId > 0) {
ImageView up = (ImageView) findViewById(upId);
up.setImageResource(R.drawable.ic_drawer_indicator);
}

The solution by #matthias doesn't work on all devices, A better solution to change the homeAsUpIndicator is to set it #null in style and change the logo resource programmatically.
Below is my code from style.xml
<style name="Theme.HomeScreen" parent="AppBaseTheme">
<item name="displayOptions">showHome|useLogo</item>
<item name="homeAsUpIndicator">#null</item>
<item name="android:homeAsUpIndicator">#null</item>
</style>
In code you can change the logo using setLogo() method.
getSupportActionBar().setLogo(R.drawable.abc_ic_ab_back_holo_light); //for ActionBarCompat
getActionBar().setLogo(R.drawable.abc_ic_ab_back_holo_light); //for default actionbar for post 3.0 devices
Also note that the Android API 18 has methods to edit the homeAsUpIndicator programatically, refer documentation.

This worked for me
getSupportActionBar().setHomeAsUpIndicator(R.drawable.my_home_as_up)

Although this answer might achieve the expected behaviour, as you can read in the comments below it: "This hack does not work on some devices". I found another way according to Adneal's answer which gives me the clue and specially the right way to do.
Lower API: use id R.id.up to retrieve the related ImageView.
API >= 14: get the relative Parent of Home ImageView (android.R.id.home) and retrieve the first child which is the UpIndicator (android.R.id.up).
Then, this snippet code changes dynamically the UpIndicator:
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
// get the parent view of home (app icon) imageview
ViewGroup home = (ViewGroup) findViewById(android.R.id.home).getParent();
// get the first child (up imageview)
( (ImageView) home.getChildAt(0) )
// change the icon according to your needs
.setImageDrawable(getResources().getDrawable(R.drawable.custom_icon_up));
} else {
// get the up imageview directly with R.id.up
( (ImageView) findViewById(R.id.up) )
.setImageDrawable(getResources().getDrawable(R.drawable.custom_icon_up));
}
I have not tested on multiple devices (that's why I'm not sure this above code works for all devices), however this seems to work great in APIs mentioned in the update part here.
Note: If you don't make the difference between higher and lower APIs, you will get a NullPointerException because R.id.up is not available in higher API while android.R.id.up is not available in lower API.

I write solution for this. It's not beautiful but works:
public static ImageView getHomeAndUpIndicator(View decorView) {
ImageView res = null;
int upId = Resources.getSystem().getIdentifier("up", "id", "android");
if (upId > 0) {
res = (ImageView) decorView.findViewById(upId);
} else {
if (android.os.Build.VERSION.SDK_INT <= 10) {
ViewGroup acbOverlay = (ViewGroup)((ViewGroup)decorView).getChildAt(0);
ViewGroup abcFrame = (ViewGroup)acbOverlay.getChildAt(0);
ViewGroup actionBar = (ViewGroup)abcFrame.getChildAt(0);
ViewGroup abLL = (ViewGroup)actionBar.getChildAt(0);
ViewGroup abLL2 = (ViewGroup)abLL.getChildAt(1);
res = (ImageView)abLL2.getChildAt(0);
} else if (android.os.Build.VERSION.SDK_INT > 10 && android.os.Build.VERSION.SDK_INT < 16) {
ViewGroup acbOverlay = (ViewGroup)((ViewGroup)decorView).getChildAt(0);
ViewGroup abcFrame = (ViewGroup)acbOverlay.getChildAt(0);
ViewGroup actionBar = (ViewGroup)abcFrame.getChildAt(0);
ViewGroup abLL = (ViewGroup)actionBar.getChildAt(1);
res = (ImageView)abLL.getChildAt(0);
} else {
ViewGroup acbOverlay = (ViewGroup)((ViewGroup)decorView).getChildAt(0);
ViewGroup abcFrame = (ViewGroup)acbOverlay.getChildAt(1);
ViewGroup actionBar = (ViewGroup)abcFrame.getChildAt(0);
ViewGroup abLL = (ViewGroup)actionBar.getChildAt(0);
ViewGroup abF = (ViewGroup)abLL.getChildAt(0);
res = (ImageView)abF.getChildAt(0);
}
}
return res;
}
As a param put: getWindow().getDecorView()
Test on few devices (nexus 7 (4.4.2), samsung galaxy s+ (2.3.6), yaiu g3 (4.2.2)) and emulators with android 2.3.3 and 4.1.1

Here is working code
final Drawable upArrow = getResources().getDrawable(R.drawable.ic_arrow_back_black_24dp);
upArrow.setColorFilter(Color.parseColor("#000000"), PorterDuff.Mode.SRC_ATOP);
getSupportActionBar().setHomeAsUpIndicator(upArrow);

How can I programmatically set android:button="#null"?

I'm trying to programmatically add a set of RadioButtons to a RadioGroup like so:
for (int i = 0; i < RANGE; i++) {
RadioButton button = new RadioButton(this);
button.setId(i);
button.setText(Integer.toString(i));
button.setChecked(i == currentHours); // Select button with same index as currently selected number of hours
button.setButtonDrawable(Color.TRANSPARENT);
button.setBackgroundResource(R.drawable.selector);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
((RadioGroup)view.getParent()).check(view.getId());
currentHours = view.getId();
}
});
radioGroupChild.addView(button);
}
and I need to set the button drawable to null (I want just text on top of my background). Manually doing this in the XML with android:button="#null" works great, but I don't want to hardcode each radio button. I've tried just doing button.setButtonDrawable(null) but it doesn't change anything.
Any help is greatly appreciated!

You need to set an empty StateListDrawable as the drawable. So the Java equivalent of android:button="#null" is:
radioButton.setButtonDrawable(new StateListDrawable());

You should do this:
button.setBackgroundDrawable(null);
If your drawable has a reference to selector you can make it transparent through your selector xml:
<item android:drawable="#android:color/transparent" />
as you'd probably found the solution ;)

setButtonDrawable(getResources().getDrawable(android.R.color.transparent))
should do the trick.
Only this worked for me.

What worked for me in multiple devices and APIs and is as simple as it gets was setButtonDrawable(android.R.color.transparent);

in Kotlin you can do that
radioButton.buttonDrawable = null

Honeycomb - customize SearchView inside the action bar

I have a field where the user can type a search query in the action bar of the application. This is declared in the action bar using a menu inflate in the Activity:
<menu
xmlns:android="http://schemas.android.com/apk/res/android"
>
<item
android:id="#+id/action_search"
android:showAsAction="ifRoom"
android:actionViewClass="android.widget.SearchView"
android:title="#string/search"
></item>
</menu>
I need to customize the appearance of the SearchView (for instance background and text color). So far I could not find a way to do it using XML (using styles or themes).
Is my only option to do it in the code when inflating the menu?
Edit #1: I have tried programmatically but I cannot get a simple way to set the text color. Plus when I do searchView.setBackgroundResource(...) The background is set on the global widget, (also when the SearchView is iconified).
Edit #2: Not much information on the Search Developer Reference either

Seibelj had an answer that is good if you want to change the icons. But you'll need to
do it for every API version. I was using ICS with ActionBarSherlock and it didn't do justice for me but it did push me in the correct direction.
Below I change the text color and hint color. I showed how you might go about changing the
icons too, though I have no interest in that for now (and you probably want to use the default icons anyways to be consistent)
#Override
public boolean onPrepareOptionsMenu(Menu menu) {
// Set up the search menu
SearchView searchView = (SearchView)menu.findItem(R.id.action_search).getActionView();
traverseView(searchView, 0);
return true;
}
private void traverseView(View view, int index) {
if (view instanceof SearchView) {
SearchView v = (SearchView) view;
for(int i = 0; i < v.getChildCount(); i++) {
traverseView(v.getChildAt(i), i);
}
} else if (view instanceof LinearLayout) {
LinearLayout ll = (LinearLayout) view;
for(int i = 0; i < ll.getChildCount(); i++) {
traverseView(ll.getChildAt(i), i);
}
} else if (view instanceof EditText) {
((EditText) view).setTextColor(Color.WHITE);
((EditText) view).setHintTextColor(R.color.blue_trans);
} else if (view instanceof TextView) {
((TextView) view).setTextColor(Color.WHITE);
} else if (view instanceof ImageView) {
// TODO dissect images and replace with custom images
} else {
Log.v("View Scout", "Undefined view type here...");
}
}

adding my take on things which is probably a little more efficient and safe across different android versions.
you can actually get a numeric ID value from a string ID name. using android's hierarchyviewer tool, you can actually find the string IDs of the things you are interested in, and then just use findViewById(...) to look them up.
the code below sets the hint and text color for the edit field itself. you could apply the same pattern for other aspects that you wish to style.
private static synchronized int getSearchSrcTextId(View view) {
if (searchSrcTextId == -1) {
searchSrcTextId = getId(view, "android:id/search_src_text");
}
return searchSrcTextId;
}
private static int getId(View view, String name) {
return view.getContext().getResources().getIdentifier(name, null, null);
}
#TargetApi(11)
private void style(View view) {
ImageView iv;
AutoCompleteTextView actv = (AutoCompleteTextView) view.findViewById(getSearchSrcTextId(view));
if (actv != null) {
actv.setHint(getDecoratedHint(actv,
searchView.getContext().getResources().getString(R.string.titleApplicationSearchHint),
R.drawable.ic_ab_search));
actv.setTextColor(view.getContext().getResources().getColor(R.color.ab_text));
actv.setHintTextColor(view.getContext().getResources().getColor(R.color.hint_text));
}
}

You can use the attribute android:actionLayout instead which lets you specify a layout to be inflated. Just have a layout with your SearchView and you won't have to modify anything really.
As to changing text style on the SearchView that is probably not possible as the SearchView is a ViewGroup. You should probably try changing text color via themes instead.

In case anyone wants to modify the views directly, here is how you can change the colors/fonts/images and customize the search box to your pleasure. It is wrapped in a try/catch in case there are differences between versions or distributions, so it won't crash the app if this fails.
// SearchView structure as we currently understand it:
// 0 => linearlayout
// 0 => textview (not sure what this does)
// 1 => image view (the search icon before it's pressed)
// 2 => linearlayout
// 0 => linearlayout
// 0 => ImageView (Search icon on the left of the search box)
// 1 => SearchView$SearchAutoComplete (Object that controls the text, subclass of TextView)
// 2 => ImageView (Cancel icon to the right of the text entry)
// 1 => linearlayout
// 0 => ImageView ('Go' icon to the right of cancel)
// 1 => ImageView (not sure what this does)
try {
LinearLayout ll = (LinearLayout) searchView.getChildAt(0);
LinearLayout ll2 = (LinearLayout) ll.getChildAt(2);
LinearLayout ll3 = (LinearLayout) ll2.getChildAt(0);
LinearLayout ll4 = (LinearLayout) ll2.getChildAt(1);
TextView search_text = (TextView) ll3.getChildAt(1);
search_text.setTextColor(R.color.search_text);
ImageView cancel_icon = (ImageView)ll3.getChildAt(2);
ImageView accept_icon = (ImageView)ll4.getChildAt(0);
cancel_icon.setBackgroundDrawable(d);
accept_icon.setBackgroundDrawable(d);
} catch (Throwable e) {
Log.e("SearchBoxConstructor", "Unable to set the custom look of the search box");
}
This example shows changing the text color and the background colors of the cancel/accept images. searchView is a SearchView object already instantiated with it's background color:
Drawable d = getResources().getDrawable(R.drawable.search_widget_background);
searchView.setBackgroundDrawable(d);
Here is the drawable code:
<?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" />
</shape>
Obviously, this is hacky, but it will work for now.

From ICS this is doable using themes and styles. I'm using ActionBarSherlock which makes it applicable also for HC and below.
Add a style to define "android:textColorHint":
<style name="Theme.MyHolo.widget" parent="#style/Theme.Holo">
<item name="android:textColorHint">#color/text_hint_corp_dark</item>
</style>
Apply this as "actionBarWidgetTheme" to your theme:
<style name="Theme.MyApp" parent="#style/Theme.Holo.Light.DarkActionBar">
...
<item name="android:actionBarWidgetTheme">#style/Theme.MyHolo.widget</item>
</style>
Presto! Make sure that you use getSupportActionBar().getThemedContext() (or getSupportActionBar() for ActionBarSherlock) if any widgets are initiated where you might have other themes in effect.

How do you inflate the menu xml in your Activity? if you inflate the menu by using getMenuInflator() in your Activity, then the menu and also the searchView get the themed context, that have attached to the activity.
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater.inflate(R.menu.search_action_menu, menu);
}
if you check the source code of Activity.getMenuInflator() at API-15, you can see the themed context codes. Here it is.
*/
public MenuInflater getMenuInflater() {
// Make sure that action views can get an appropriate theme.
if (mMenuInflater == null) {
initActionBar();
if (mActionBar != null) {
mMenuInflater = new MenuInflater(mActionBar.getThemedContext());
} else {
mMenuInflater = new MenuInflater(this);
}
}
return mMenuInflater;
}

Creating an Android View with a particular style programmatically

Other questions say that the style cannot be set programmatically, but a View can be initialised with a style such as when it is loaded from XML.
How can I initialise a View with a particular style programmaticly (not in XML)? I tried using View(Context context, AttributeSet attrs, int defStyle), but I don't know what to parse in for the second argument. Passing in null results in the View not being displayed

I'm having the same problem, but haven't found any practical way to directly set a style programmatically, so far. I would like to populate my screen with a lot of widgets, of a given type, let's say buttons. It is impractical to define them all in the layout file. I would like to create them programmatically, but I would also like to define their style in a style xml file.
The solution I have devised consists in defining just one of those widgets in the layout file, create all the others programmatically, and clone the style info from the first one to the other ones.
An example follows.
In the style file, define the style for your buttons. For example:
<style name="niceButton">
<item name="android:layout_width">160dip</item>
<item name="android:layout_height">60dip</item>
<item name="android:gravity">center</item>
<item name="android:textSize">18dip</item>
<item name="android:textColor">#000000</item>
</style>
Then subclass class "Button", by deriving a class "NiceButton". Define the constructor that will be needed by the inflater:
public NiceButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
Then define another constructor, which purpose is to clone an existing button:
public NiceButton(int id, NiceButton origButton) {
super(origButton.getContext());
setId(id);
setLayoutParams(origButton.getLayoutParams());
setGravity(origButton.getGravity());
setPadding(origButton.getPaddingLeft(),
origButton.getPaddingTop(),
origButton.getPaddingRight(),
origButton.getPaddingBottom());
setTextSize(TypedValue.COMPLEX_UNIT_PX, origButton.getTextSize());
setTextColor(origButton.getTextColors());
// ... also copy whatever other attributes you care about
}
In your layout file, define just the first one of your buttons. Suppose for example that you want to put your buttons in a table:
<TableLayout android:id="#+id/button_table"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TableRow android:id="#+id/button_row_0">
<com.mydomain.mypackage.NiceButton
style="#style/niceButton" android:id="#+id/button_0" />
<!-- More rows/buttons created programmatically -->
</TableRow>
</TableLayout>
Notice that the full qualified name of the widget class is used; obviously, you will have to replace com.mydomain.mypackage with the actual package name.
In your activity, you may want to define an array which is going to hold a reference to all of the buttons, and a common listener to be called when any of the buttons is pressed:
NiceButton[] mButtonViews = new NiceButton[10];
private View.OnClickListener mNiceButtonClickListener = new View.OnClickListener() {
public void onClick(View view) {
int i = view.getId();
mButtonViews[i].setText("PRESSED!");
}
};
Notice how the view id is used as an index in the array of buttons. So you will need your buttons to have an id from 0 to n-1.
Finally, here is the way you can create your buttons in the onCreate method:
// Retrieve some elements from the layout
TableLayout table = (TableLayout)findViewById(R.id.button_table);
TableRow row = (TableRow)findViewById(R.id.button_row_0);
NiceButton origButton = (NiceButton)findViewById(R.id.button_0);
// Prepare button 0
origButton.setId(0);
origButton.setText("Button 0");
origButton.setOnClickListener(mNiceButtonClickListener);
mButtonViews[0] = origButton;
// Create buttons 1 to 10
for (int i = 1; i < 10; i++) {
if (i % 2 == 0) {
row = new TableRow(this);
table.addView(row);
}
NiceButton button = new NiceButton(i, origButton);
button.setText("Button " + i);
button.setOnClickListener(mNiceButtonClickListener);
mButtonViews[i] = button;
row.addView(button);
}
Here's how the screen appears after you have pressed some buttons:
Well, there's some code involved, but in the end you can create as many widgets you want programmatically, and still have their attributes defined as a style.

If you want to style a view you have 2 choices: the simplest one is to just specify all the elements in code:
button.setTextColor(Color.RED);
button.setTextSize(TypedValue.COMPLEX_UNIT_SP, 18);
The other option is to define the style in XML, and apply it to the view. In the general case, you can use a ContextThemeWrapper for this:
ContextThemeWrapper newContext = new ContextThemeWrapper(baseContext, R.style.MyStyle);
button = new Button(newContext);
To change the text-related attributes on a TextView (or its subclasses like Button) there is a special method:
button.setTextAppearance(context, R.style.MyTextStyle);
This last one cannot be used to change all attributes; for example to change padding you need to use a ContextThemeWrapper. But for text color, size, etc. you can use setTextAppearance.

AttributeSet contains the list of attributes specified in xml (ex. layout_width, layout_height etc).
If you are passing it as null, then you should explicitly set the height/width of view.