Binding to Data with AdapterView

Android應用程式學習筆記

Binding to Data with AdapterView

AdapterView是ViewGroup的子類，它的子View是通過Adapter綁定的數據形式所決定的。AdapterView不管你想在何時顯示數據都是可用的。

Gallery、ListView和Spinner是AdapterView的子類的例子，你可以綁定特定數據並顯示。

AdapterView物件有兩個主要屬性:

• 把數據填充到佈局上。
• 處理用戶的選擇。

Filling the  layout with data

插入到佈局的數據通常通過AdapterView綁定倒是配器上的，它從外部資源取得數據。

以下為例子:

1. 建立Spinner，綁定一個新的ArrayAdapter，ArrayAdapter從資源中讀取顏色陣列。
2. 從一個View建立另一個Spinner，並與SimpleCursorAdapter綁定，從聯絡人中讀取姓名。

// Get a Spinner and bind it to an ArrayAdapter that 
// references a String array.
Spinner s1 = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter adapter = ArrayAdapter.createFromResource(
    this, R.array.colors, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s1.setAdapter(adapter);
// Load a Spinner and bind it to a data query.
private static String[] PROJECTION = new String[] {
        People._ID, People.NAME
    };
Spinner s2 = (Spinner) findViewById(R.id.spinner2);
Cursor cur = managedQuery(People.CONTENT_URI, PROJECTION, null, null);
     SimpleCursorAdapter adapter2 = new SimpleCursorAdapter(this,
    android.R.layout.simple_spinner_item, // Use a template
                                          // that displays a
                                          // text view
    cur, // Give the cursor to the list adapter
    new String[] {People.NAME}, // Map the NAME column in the
                                         // people database to...
    new int[] {android.R.id.text1}); // The "text1" view defined in
                                     // the XML template
                                         
adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s2.setAdapter(adapter2);

Handling User Selection

// Create a message handling object as an anonymous class.
private OnItemClickListener mMessageClickedHandler = new OnItemClickListener() {
    public void onItemClick(AdapterView parent, View v, int position, long id)
    {
        // Display a messagebox.
        Toast.makeText(mContext,"You've got an event",Toast.LENGTH_SHORT).show();
    }
};
// Now hook into our object and set its onItemClickListener member
// to our class handler object.
mHistoryView = (ListView)findViewById(R.id.history);
mHistoryView.setOnItemClickListener(mMessageClickedHandler);