多个类定义attr属性重复的问题:Attribute "xxx" has already been defined

如果从单独开发app的话，可能不会遇到多个自定义类的attribute 的名字重复的问题。但是如果是团队合作开发的话，可能会碰到这样的问题，A和B自定义的两个类都用了同一个名字来定义属性，这时系统会报出警告，Attribute
"xxx" has already been defined. A和B又都不想修改自己的名字，这时就很头痛。

下面举个例子，在values文件夹下定义一个上面的attrs.xml的文件，eclipse即会报错：Attribute
"icon" has already been defined。因为在PreferenceHeader, Preference两个属性集里定义了两个相同的属性。

<? xml version = "1.0" encoding = "utf-8" ?>
< resources >
     < declare-styleable name= "PreferenceHeader" >
        <!-- Identifier value for the header. -->
        < attr name= "id" format = "integer"/>
        < attr name= "icon" format = "integer" />
        <!-- The fragment that is displayed when the user selects this item. -->
    </declare-styleable >
    < declare-styleable name= "Preference" >
        < attr name= "icon" format = "integer" />
        <!-- The key to store the Preference value. -->
        < attr name= "key" format = "string" />
    </declare-styleable >
</ resources >

解决方案：

1.在xml文件里前面先声明属性

2.然后在属性集合里引用声明的属性即可。

以上面的文件为例来修改，如下：

<? xml version = "1.0" encoding = "utf-8" ?>
< resources >
     < attr name = "icon" format = "integer" />
     < declare-styleable name= "PreferenceHeader" >
        <!-- Identifier value for the header. -->
        < attr name= "id" format = "integer"/>
        < attr name= "icon" />
        <!-- The fragment that is displayed when the user selects this item. -->
    </declare-styleable >
    < declare-styleable name= "Preference" >
        < attr name= "icon"  />
        <!-- The key to store the Preference value. -->
        < attr name= "key" format = "string" />
    </declare-styleable >
</ resources >