這個問題網上有很多答案：
過去只有FILL_PARENT和WRAP_CONTENT那麽match_parent到底是什麽類型呢? 其實從Android 2.2開始FILL_PARENT改名為MATCH_PARENT ，從API Level為8開始我們可以直接用MATCH_PARENT來代替FILL_PARENT，最後結論，他們的定義本質是壹樣均為-1，只是換了個別名，可能為了更準確些，比如最終在SDK中的定義為:
（1）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.
（2）match_parent -1 The view should be as big as its parent (minus padding). Introduced in API Level 8.
（3）wrap_content -2 The view should be only big enough to enclose its content (plus padding).