Develop Reference

How do i change from the default look of a list activity list?

I have created a list activity class and made an array adapter. However, how would i change the appearance of the list it generates when run. As in how do i change the colour, style etc.
Thank you in advance.

You can create a styles.xml in your values folder then do something like
<!-- ListView -->
<style name="List_Item" parent="#android:style/Widget.ListView">
<item name="android:background">#drawable/list_item_bg</item> // if you have a drawable you want to use
//add whatever other attributes you want
</style>
then in the xml with your ListView delcare your style
<ListView
android:id="#+id/listID"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/search_plate"
style="#style/List_Item"/> //here you implement your style

You can use Theme & Styles and xml attributes for ListView or any View inside your ListView

How to set style for spinner programmatically?

I have spinner with a style selection (I set the spinner style in strings.xml) and it's works well if I set the style in main.xml. But I want to know how to set the style programmatically in which the style already defined in strings.xml.
Refer my code below
main.xml:
<Spinner
android:id="#+id/PassengersSpinner1"
android:layout_width="100dp"
android:layout_height="40dp"
android:layout_span="3"
android:layout_marginTop="6dp"
style="#style/SpinnerStyle" />
strings.xml:
<style
name="SpinnerStyle"
parent="#android:style/Widget.Spinner">
<item name="android:background">#android:drawable/btn_default</item>
</style>
Now, I want to know that how can I set this strings.xml programmatically without main.xml?

From all my reading, you cannot do it, because the style has to be set before the view is created.
You can do it if you create the view in code (since then you can set the style before creating the view).
If you want to do that, a good example is here. Both the question and the answer give you methods to achieve your goal.

Android - use attributes to tweak custom styles

here's my issue. I have defined custom themes and styles, so as to customize various Views, in the relevant .xml files. Here are some code extracts:
themes.xml:
...
<style name="Legacy" parent="android:Theme.NoTitleBar">
<item name="android:buttonStyle">#style/Legacy.Button</item>
...
</style>
styles.xml:
...
<style name="Legacy.Button" parent="#android:style/Widget.Button">
<item name="android:textColor">#ffffff</item>
<item name="android:background">#drawable/button_selector_blue</item>
<item name="android:textSize">15dp</item>
</style>
Let's say I set my application's theme to Legacy. If I use a Button in a layout, it will get my custom default parameters (white text, background is #drawable/button_selector_blue, etc).
Now let's say I want to keep those parameters save for the text size: I'd like to have some buttons with a larger text size, which would be defined in an titleSize attribute in attrs.xml:
...
<attr name="titleSize" format="reference|dimension" />
and which value is set for each theme in my themes.xml file.
So my layout would contain something like:
<Button
android:id="#+idmyButtonId"
android:drawableRight="#drawable/aDrawable"
android:text="#string/someText"
android:textSize="?titleSize"
android:layout_width="fill_parent" android:layout_height="wrap_content">
</Button>
When launching my app I get the following error:
java.lang.UnsupportedOperationException: Can't convert to dimension: type=0x2
So it seems I cannot tweak custom styles using attributes - at least not this way. Is such a thing possible ? If not, what would you use to achieve such a result ?
I'd like to give the user the ability to select among different themes, so I can't just define an additionnal ButtonWithLargeText style and directly use it in my layout.
Thanks for your help !

I finally got it to work. Instead of defining my titles' size in attrs.xml, I used dimens.xml. So now the following works:
<Button
android:id="#+idmyButtonId"
android:drawableRight="#drawable/aDrawable"
android:text="#string/someText"
android:textSize="#dimen/titleSize"
android:layout_width="fill_parent" android:layout_height="wrap_content">
</Button>
While I get my regular text size (which I defined in my styles.xml) on the Button by using this:
<Button
android:id="#+id/idRegularButton"
android:text="#string/regularSizeText"
android:layout_width="wrap_content" android:layout_height="wrap_content">
</Button>

set the textsize of a listview

I have a custom listview and have defined a style for it. I am not able to change the textsize of the items on listview. I am trying to change it through layout so that it can dynamically change depending on device.
styles.xml
<style parent="#android:attr/listViewStyle" name="ListStyle">
<item name="android:background">#android:color/white</item>
<item name="android:divider">#drawable/divider</item>
<item name="android:textSize">26dp</item>
<item name="android:textStyle">bold</item>
</style>
xml layout
<TvList style="ListStyle"
android:id="#+id/mainview"
android:layout_height="300dp"
android:layout_width="wrap_content" />
I know that i can use setTextSize in my code for changing the font size . But i want to change it applying styles.
Any suggestions on how to go about changing it?
Thanks

The size of the text within the List View is defined by the ListView's adapter's item resource. If you create a custom view for the list view item and define a TextView, you can change the size of the font within that text view, which will define the size of the text in each item within the List.

I would say the best way is to define resource files that you want and then override them in different configurations. For example, create a values/dimen.xml file and define:
<dimen name="text_size_medium">18sp</dimen>
and then create another file values-large/dimen.xml which defines
<dimen name="text_size_medium">22sp</dimen>
Then you just say in your styles.xml:
<item name="android:textSize">#dimen/text_size_medium</item>

How do I change the text style of a spinner?

I'm creating a spinner in my layout xml files and setting an string array to this spinner.
If I change the textstyle of the spinner the text is not affected by the changes.
I read in the googlegroups that a spinner has no text and therefore the textstyle can not be changed and I have to change the style of the textview that is shown in the spinner. But how can I do that. Preferably in my xml file.

As my predecessor specified, you can't do it on the main XML layout file where the Spinner component is.
And the answer above is nice, but if we want to use Google's best practices, like you know... to use styles for everything... you could do it in 3 'easy' steps as follows:
Step 1: You need an extra file under your layout folder with the look for the Spinner's items:
<?xml version="1.0" encoding="utf-8"?>
<TextView
android:id="#+id/textViewSpinnerItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="#style/SpinnerTextViewItem"
xmlns:android="http://schemas.android.com/apk/res/android" />
Name this file: spinner_item_text.xml
Step 2: Then, on your Activity Class when you are filling the Spinner with an array of items:
adapter = new ArrayAdapter<CharSequence>(this, R.layout.spinner_item_text, items);
spinner.setAdapter(adapter);
Note that the R.layout.spinner_item_text resource is in your own R's file.
Step 3: Under your values folder, create or use (you might have one already) the file styles.xml. The style entry needed should look like this one:
<style name="SpinnerTextViewItem" parent="#android:style/Widget.TextView" >
<item name="android:textSize" >8dp</item>
<item name="android:textStyle" >bold</item>
</style>
And that's it!
So far it has been really, really handy to put all about text sizes, styles, colors, etc... on a styles.xml file so it's easy to maintain.

Via XML Only
As a follow-up to #Cyril REAL's excellent answer, here is a thorough implementation of how to style your Spinners just through XML if you're populating your Spinner via android:entries.
The above answers work if you're creating your Spinner via code but if you're setting your Spinner entries via XML, i.e. using android:entries, then you can adjust the text size and other attributes with the following two theme settings:
In your res/values/styles.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="AppBaseTheme" parent="android:Theme.Holo">
</style>
<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
<!-- For the resting Spinner style -->
<item name="android:spinnerItemStyle">
#style/spinnerItemStyle
</item>
<!-- For each individual Spinner list item once clicked on -->
<item name="android:spinnerDropDownItemStyle">
#style/spinnerDropDownItemStyle
</item>
</style>
<style name="spinnerItemStyle">
<item name="android:padding">10dp</item>
<item name="android:textSize">20sp</item>
<item name="android:textColor">#FFFFFF</item>
</style>
<style name="spinnerDropDownItemStyle">
<item name="android:padding">20dp</item>
<item name="android:textSize">30sp</item>
<item name="android:textColor">#FFFFFF</item>
</style>
</resources>

When you create the Adapter that backs the Spinner you can set a layout for the spinner item.
spinner.setAdapter(new ArrayAdapter(this, R.id.some_text_view));
You can style some_text_view the way you want.
<TextView android:id="#+id/some_text_view" android:textStyle="bold" />

Actually you can customize spinner's text by xml.
In your own style, define a :
<item name="android:spinnerItemStyle">#style/yourStyleForSpinnerItem</item>
and define this style also :
<style name="yourStyleForSpinnerItem">
// Stuff you want for the item style.
</style>
When you instantiate the spinner's adapter in the java code, you can use the default android.R.layout.simple_spinner_item

If you don't want such workarounds, there's a simple way. Get the textview from the spinner and change its parameters:
TextView tv = (TextView) spin.getSelectedView();
tv.setTypeface(Typeface.DEFAULT_BOLD); //to make text bold
tv.setTypeface(Typeface.DEFAULT); //to make text normal

if you want just change background of popup View in spinner, call this method:
spinner.setPopupBackgroundResource(R.color.pa_md_white);