很多人表示对于很多工程中的MATCH_PARENT出现在layout中感到不明白，过去只有FILL_PARENT和WRAP_CONTENT那么 match_parent到底是什么类型呢? 其实从Android 2.2开始FILL_PARENT改名为MATCH_PARENT ，从API Level为8开始我们可以直接用MATCH_PARENT来代替FILL_PARENT，最后Android123提醒大家，他们的定义本质是一样均为 -1，只是换了个别名，可能为了更准确些，比如最终在SDK中的定义为:

fill_parent   -1  The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent.  
match_parent   -1 The view should be as big as its parent (minus padding). Introduced in API Level 8.  
wrap_content   -2  The view should be only big enough to enclose its content (plus padding).