Question

您好我有一个运行我的getQus类的类（通过asynctask）现在的问题是我试图以这样的方式设置它，如果我的返回结果为null，用更新的变量再次重新运行getQus，即增加我的主题＆amp;直到我得到一个有效的结果。

这是我的系统流程。第一类（设置主题＆amp; lvl） - ＆gt;将主题＆amp; lvl传递给getQus - ＆gt; getQus通过onPostExecute（委托）返回结果。

第一类代码

 public void GenerateQus(){
    //run code to get new qus
    x.setLvl(lvl);
    x.setTopic(topic);
    System.out.println("GENERATEQUS:"+ lvl +" , "+topic);
    new getQus(CAT.this).execute(x);
}

getQus Class

    protected Question doInBackground(Level... params) {
    int r = params[0].getLvl();
    int z = params[0].getTopic();
    System.out.println("getQlvl:" + r);
    System.out.println("getQtopic:" + z);

    String range = String.valueOf(r);
    String topic = String.valueOf(z);

    // TODO Auto-generated method stub
    ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("range",range));
    nameValuePairs.add(new BasicNameValuePair("topic",topic));
    int q_id = 0;
    String result=null;
    String q_qus =" ";
    String result2 = " ";

    Question q = new Question();


     InputStream is = null;
        try {
            Globals g = Globals.getInstance();
               String ip = g.getip();
              HttpClient httpclient = new DefaultHttpClient();
                HttpPost httppost = new HttpPost("http://"+ip+"/fyp/qus.php");
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                is = entity.getContent();
        }catch(Exception e){
                Log.e("log_tag", "Error in http connection "+e.toString());
        }
        //convert response to string
        try{

            BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                        sb.append(line + "\n");
                }
                is.close();

                result2=sb.toString();
                System.out.println("TEDASD: "+result2);

                if(result2.equals("[]")){
                    //to rerun again
                }

我该怎么办才能让getQus再次重新召唤自己？提前谢谢！

Answer 1

在onPostExecute（）方法中，您将获得结果。所以，如果你的结果为null，那么就开始使用AysncTask itselt。

Answer 2

如果我理解你的问题，你只想在doInBackground中重新运行逻辑。那么，你为什么不这样做呢？

protected Question doInBackground(Level... params) {
    Question q;
    while((q = doTheStuff(params))==null){
        updateParams(params);
    }
    return q;
}

private Question doTheStuff(Level.. params){
    //your logic here
}

private void updateParams(Level.. params){
    //update params here
}

如果只能在主线程中更新x，则可以在onPostExecute中重新执行该任务：

public class SomeActivity extends Activity {

    private X x = new X();

    @Override protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        new AsyncTask<X, String, Long>() {

            @Override protected Long doInBackground(final X... params) {
                //  do something here
                return null;
            }

            @Override protected void onPostExecute(final Long result) {
                if (result == null) {
                    //  update args and restart task
                    x.setFoo("a");
                    x.setBar("b");
                    execute(x);
                }

            }
        }.execute(x);
    }

    private class X {
        String foo;
        String bar;

        public void setFoo(final String foo) {
            this.foo = foo;
        }

        public void setBar(final String bar) {
            this.bar = bar;
        }
    }
}

Asynctask类再次重新运行？

2 个答案: