Usage of Selector in Android

Selector in Android is mainly used to change the default background of ListView and Button controls. You can follow the steps below to design the method:

Take mylist_view.xml as an example)

1. Create the mylist_view.xml File

First, create a drawable folder under the res directory, and then create mylist_view.xml in the new drawable folder. The directory structure is res/drawable/mylist_view.xml.

2. Edit the mylist_view.xml file as needed

After the mylist_view.xml file is created, its internal code structure is:

1. <? Xmlversion = "1.0" encoding = "UTF-8"?>

2. <Selectorxmlns: android = "http://schemas.android.com/apk/res/android">

3. </Selector>

You can define the style you want internally according to the project requirements. The main attributes are as follows:

1. <? Xmlversion = "1.0" encoding = "UTF-8"?>

2. <Selectorxmlns: android = "http://schemas.android.com/apk/res/android">

3. <! -- Default background image -->

4. <Itemandroid: drawable = "@ drawable/pic1"/>

5. <! -- Background image without focus -->

6. <Itemandroid: state_window_focused = "false"

7. Android: drawable = "@ drawable/pic1"/>

8. <! -- Background image when the focus is obtained in non-touch mode and clicked -->

9. <Itemandroid: state_focused = "true" android: state_pressed = "true" android: drawable = "@ drawable/pic2"/>

10. <! -- Background image when clicked in touch mode -->

11. <Itemandroid: state_focused = "false" android: state_pressed = "true" android: drawable = "@ drawable/pic3"/>

12. <! -- Background of the selected image -->

13. <Itemandroid: state_selected = "true" android: drawable = "@ drawable/pic4"/>

14. <! -- Background of the image when the focus is obtained -->

15. <Itemandroid: state_focused = "true" android: drawable = "@ drawable/pic5"/>

16. </Selector>

3. Reference The mylist_view.xml File

Three methods can be used to reference the file just created:

1) Add the following property code to ListView:

1. Android: listSelector = "@ drawable/mylist_view"

2) Add the following property code to the item interface of ListView:

1. Android: background = "@ drawable/mylist_view"

3) use JAVA code to directly write

1. Drawable drawable = getResources (). getDrawable (R. drawable. mylist_view );

2. ListView. setSelector (drawable );

To prevent list blacklisting, add the following property code to ListView:

1. Android: cacheColorHint = "@ android: color/transparent"

Attribute introduction:

Android: state_selected

Android: state_focused get focus

Android: state_pressed click

Android: state_enabled: sets whether to respond to events. It indicates all events.

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