如何异步运行FilterQueryProvider的查询？

问题描述

我使用的是FilterQueryProvider到由一个自定义的CursorAdapter备份列表视图的内容进行过滤。

I'm using a FilterQueryProvider to filter the content of a list view which is backed up by a custom CursorAdapter.

要使用FilterQueryProvider你必须重写它返回一个游标对象runQuery（）方法。现在，我不知道如何为游标查询以异步方式，以避免阻塞UI线程。

To use the FilterQueryProvider you have to override the runQuery() method which returns a Cursor object. Now I'm wondering how to query for the cursor asynchronously to avoid blocking the UI thread.

是否有某种最佳实践？我找不到无论是在UI线程或它自己的线程执行的runQuery（）方法的任何信息。

Is there some kind of best practice? I couldn't find any information whether the the runQuery() method is executed on the UI-thread or on its own thread.

推荐答案

从文档：

过滤操作，
  android.widget.Filter.FilterListener）都是异步执行

所以你的code应该是这样的：

So your code should look like this :

private void filterList(CharSequence constraint) {
    final YourListCursorAdapter adapter = 
        (YourListCursorAdapter) getListAdapter();
    final Cursor oldCursor = adapter.getCursor();
    adapter.setFilterQueryProvider(filterQueryProvider);
    adapter.getFilter().filter(constraint, new FilterListener() {
        public void onFilterComplete(int count) {
            // assuming your activity manages the Cursor 
            stopManagingCursor(oldCursor);
            final Cursor newCursor = adapter.getCursor();
            startManagingCursor(newCursor);
            // safely close the oldCursor
            if (oldCursor != null && !oldCursor.isClosed()) {
                oldCursor.close();
            }
        }
    });
}

private FilterQueryProvider filterQueryProvider = new FilterQueryProvider() {
    public Cursor runQuery(CharSequence constraint) {
        return dbHelper.getListCursor(constraint);
    }
};

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