Android 官方文檔：（三）資源 —— 3.6.3 顏色狀態表

A ColorStateList is an object you can define in XMLthat you can apply as a color, but will actually change colors, depending on the state ofthe View object to which it is applied. For example, a Button widget can exist in one of several different states (pressed, focused,or niether) and, using a color state list, you can provide a different color during each state.

You can describe the state list in an XML file. Each color is defined in an <item> element inside a single <selector> element. Each <item>uses various attributes to describe the state in which it should be used.

During each state change, the state list is traversed top to bottom and the first item thatmatches the current state will be used—the selection is not based on the "bestmatch," but simply the first item that meets the minimum criteria of the state.

Note: If you want to provide a static color resource, use asimple Color value.

file location:

res/color/filename.xml
The filename will be used as the resource ID.

compiled resource datatype:

Resource pointer to a ColorStateList.

resource reference:

In Java: R.color.filename
In XML: @[package:]color/filename

syntax:

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android" >    <item        android:color="hex_color"        android:state_pressed=["true" | "false"]        android:state_focused=["true" | "false"]        android:state_selected=["true" | "false"]        android:state_checkable=["true" | "false"]        android:state_checked=["true" | "false"]        android:state_enabled=["true" | "false"]        android:state_window_focused=["true" | "false"] /></selector>

elements:

<selector>

Required. This must be the root element. Contains one or more <item> elements.

attributes:

xmlns:android

String. Required. Defines the XML namespace, which must be "http://schemas.android.com/apk/res/android".

<item>

Defines a color to use during certain states, as described by its attributes. Must be achild of a <selector> element.

attributes:

android:color

Hexadeximal color. Required. The color is specified with anRGB value and optional alpha channel.

The value always begins with a pound (#) character and then followed by theAlpha-Red-Green-Blue information in one of the following formats:

• #RGB
• #ARGB
• #RRGGBB
• #AARRGGBB

android:state_pressed

Boolean. "true" if this item should be used when the object is pressed (such as when a buttonis touched/clicked); "false" if this item should be used in the default, non-pressed state.

android:state_focused

Boolean. "true" if this item should be used when the object is focused (such as when a buttonis highlighted using the trackball/d-pad); "false" if this item should be used in the default,non-focused state.

android:state_selected

Boolean. "true" if this item should be used when the object is selected (such as when atab is opened); "false" if this item should be used when the object is not selected.

android:state_checkable

Boolean. "true" if this item should be used when the object is checkable; "false" if thisitem should be used when the object is not checkable. (Only useful if the object cantransition between a checkable and non-checkable widget.)

android:state_checked

Boolean. "true" if this item should be used when the object is checked; "false" if itshould be used when the object is un-checked.

android:state_enabled

Boolean. "true" if this item should be used when the object is enabled (capable ofreceiving touch/click events); "false" if it should be used when the object is disabled.

android:state_window_focused

Boolean. "true" if this item should be used when the application window has focus (theapplication is in the foreground), "false" if this item should be used when the applicationwindow does not have focus (for example, if the notification shade is pulled down or a dialog appears).

Note: Remember that the first item in the state list thatmatches the current state of the object will be applied. So if the first item in the list containsnone of the state attributes above, then it will be applied every time, which is why yourdefault value should always be last (as demonstrated in the following example).

example:

XML file saved at res/color/button_text.xml:

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="true"          android:color="#ffff0000"/> <!-- pressed -->    <item android:state_focused="true"          android:color="#ff0000ff"/> <!-- focused -->    <item android:color="#ff000000"/> <!-- default --></selector>

This layout XML will apply the color list to a View:

<Button    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:text="@string/button_text"    android:textColor="@color/button_text" />

see also:

• Color (simple value)
• ColorStateList
• State List Drawable