１ 創建fragment
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_arguments_support);
if (savedInstanceState == null) {
// First-time init; create fragment to embed in activity.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Fragment newFragment = MyFragment.newInstance("From Arguments");
ft.add(R.id.created, newFragment);
ft.commit();
}
}2 tools:text 和android:text區別
android:text --> what you would see while running the app
tools:text --> what you would see just on preview window (when you need to design layout, but won't it to see on layout in app)
xmlns:tools="http://schemas.android.com/tools"
tools可以告訴Android Studio，哪些屬性在運行的時候是被忽略的，只在設計佈局的時候有效。
３ RecyclerView.onBindViewHolder called only once
原因：Make sure you set layout_height =" wrap_content" of RecyclerView child item.
４ Only one item displaying in recycler view. 顯示列表的時候，有三條記錄，卻僅僅顯示第一條。
具體佈局：<RecyclerView> <RelativeLayout/> <TextView/>
</RecyclerView>
方案： Change height of LinearLayout to wrap_content in itemlist.xml
android:layout_height="wrap_content"
That means : RecyclerView and RelativeLayout both need to set
layout_height="wrap_content"
5