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returns its query results to your implementation of, in the form of a . In the callback, you can update your data display, do further processing on the data, and so forth. http://blog.csdn.net/sergeycao

When the loader framework detects changes to data associated with the query, it resets the, closes the current , and then invokes your implementation of. Use this callback to delete references to the current; when the loader framework destroys the , you won't have outstanding references that cause memory leaks.

Handle Query Results

The following two snippets are an example of displaying the results of a query, using a backed by a .

The first snippet shows the and :

// Gets a handle to the Android built-in ListView widgetmListView = ((ListView) findViewById(android.R.id.list));// Creates a CursorAdaptermAdapter =    new SimpleCursorAdapter(    this,                   // Current context    R.layout.logitem,       // View for each item in the list    null,                   // Don't provide the cursor yet    FROM_COLUMNS,           // List of cursor columns to display    TO_FIELDS,              // List of TextViews in each line    0                       // flags);// Links the adapter to the ListViewmListView.setAdapter(mAdapter);

The next snippet shows an implementation of that moves the query results in the returned to the . Changing the in the triggers a refresh of the with the new data:

public void onLoadFinished(Loader
   
     loader, Cursor cursor){    /*     * Move the results into the adapter. This     * triggers the ListView to re-display.     */    mAdapter.swapCursor(cursor);}
   

Handle a Loader Reset

The loader framework resets the whenever the becomes invalid. This usually occurs because the data associated with the has changed. Before re-running the query, the framework calls your implementation of. In this callback, make sure to prevent memory leaks by deleting all references to the current. Once you return from , the loader framework re-runs the query.

For example:

public void onLoaderReset(Loader
   
     loader){    // Remove the reference to the current Cursor    mAdapter.swapCursor(null);}