Question

我正在尝试在gridView中显示图像。这些图像来自对ElasticSearch服务器的研究。用户在文本字段中提供关键字，ElasticSearch上的查询结果是字符串列表（图像的网址），图像显示在gridView中。

按下按钮进行研究时的动作：

public void sendMessage(View view){

    imgAdapter.clearmThumbIds();  //mThumbs is a list of string (urls image)

    gridView = (GridView) findViewById(R.id.grid_view);
    EditText editText = (EditText) findViewById(R.id.searchBar);
    String message = editText.getText().toString();          
    try {
        eSearchElastic.ESE(imgAdapter,message);
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    System.out.println("Etape 2");
    gridView.setAdapter(imgAdapter);


}

eSearchElastic.java

public static void ESE (final ImageAdapter imgAdapter,final String keyword)throws ClientProtocolException, IOException {

AsyncTask<Void, Void, Void> task = new AsyncTask<Void, Void, Void>(){
    @Override
    protected Void doInBackground(Void... params) {

        //Build the query, connect to ElasticServer and receive a list or urls of image as answer
         System.out.println("Etape 1");
        return null;
    }

};
task.execute();}

在Etape1之前打印Etape2的结果和我希望这行“gridView.setAdapter（imgAdapter）”仅在eSearchElastic的后台进程/线程完成后执行。我怎样才能做到这一点？

Answer 1

只需在gridView.setAdapter(imgAdapter);内的onPostExecute()方法中拨打AsyncTask，而不是从sendMessage()调用doInBackground()。保证仅在public static void ESE (final GridView gridView, final ImageAdapter imgAdapter, final String keyword) throws ClientProtocolException, IOException { AsyncTask<Void, Void, Void> task = new AsyncTask<Void, Void, Void>(){ @Override protected Void doInBackground(Void... params) { // Build the query, connect to ElasticServer and receive a list or urls of image as answer System.out.println("Etape 1"); return null; } @Override protected void onPostExecute(Void result) { super.onPostExecute(result); gridView.setAdapter(imgAdapter); } }; task.execute(); }方法完成后调用，并且将在主线程上调用，因此触摸UI是安全的。

例如：

{{1}}

使用asynctask“安排”我的程序？

1 个答案: