先說下標籤的第一個比較簡單的用法。如果我們使用FrameLayout作爲activity's content view的父元素(也就是在main.xml裏把它寫在最外層),那麼可以考慮用替換標籤。官方文檔給出的解釋是這樣做可以減少一級佈局層次達到優化佈局的效果。
這是文檔裏關於這部分結論的原文,個人E文水平有限,直接貼出來好了:
Obviously, using works in this case because the parent of an activity's content view is always a FrameLayout. You could not apply this trick if your layout was using a LinearLayout as its root tag for instance.
關於merge標籤和include標籤的使用,直接用實例說明吧。
TestMergeInclude.java
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public class TestMergeInclude extends Activity
{ @Override public void onCreate(Bundle
savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.main); } } |