我试图同时运行两个AsyncTasks。(平台为Android 1.5, HTC Hero)
但是，只执行第一个。下面是一个简单的片段来描述我的问题:
public class AndroidJunk extends Activity {
class PrinterTask extends AsyncTask<String, Void, Void> {
protected Void doInBackground(String ... x) {
while (true) {
System.out.println(x[0]);
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
ie.printStackTrace();
}
}
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new PrinterTask().execute("bar bar bar");
new PrinterTask().execute("foo foo foo");
System.out.println("onCreate() is done.");
}
}
我期望的输出是:
onCreate() is done.
bar bar bar
foo foo foo
bar bar bar
foo foo foo
等等。然而，我得到的是:
onCreate() is done.
bar bar bar
bar bar bar
bar bar bar
第二个AsyncTask永远不会被执行。如果我改变execute()语句的顺序，只有foo任务将产生输出。
我是否遗漏了一些明显的东西，或者做了一些愚蠢的事情?不可能同时运行两个asynctask吗?
编辑:我意识到问题手机运行Android 1.5，我更新了问题描述。相应的行动。运行Android 2.1的HTC Hero就没有这个问题。嗯…
这是可能的。
我的android设备版本是4.0.4和android.os. build . version。SDK_INT是15
我有3个旋转器
Spinner c_fruit=(Spinner) findViewById(R.id.fruits);
Spinner c_vegetable=(Spinner) findViewById(R.id.vegetables);
Spinner c_beverage=(Spinner) findViewById(R.id.beverages);
我还有一个Async-Tack类。
这是我的转轮加载代码
RequestSend reqs_fruit = new RequestSend(this);
reqs_fruit.where="Get_fruit_List";
reqs_fruit.title="Loading fruit";
reqs_fruit.execute();
RequestSend reqs_vegetable = new RequestSend(this);
reqs_vegetable.where="Get_vegetable_List";
reqs_vegetable.title="Loading vegetable";
reqs_vegetable.execute();
RequestSend reqs_beverage = new RequestSend(this);
reqs_beverage.where="Get_beverage_List";
reqs_beverage.title="Loading beverage";
reqs_beverage.execute();
这工作得很完美。我的纺纱机一个接一个装上。我没有使用executeOnExecutor。
这是我的异步任务类
public class RequestSend extends AsyncTask<String, String, String > {
private ProgressDialog dialog = null;
public Spinner spin;
public String where;
public String title;
Context con;
Activity activity;
String[] items;
public RequestSend(Context activityContext) {
con = activityContext;
dialog = new ProgressDialog(activityContext);
this.activity = activityContext;
}
@Override
protected void onPostExecute(String result) {
try {
ArrayAdapter<String> adapter = new ArrayAdapter<String> (activity, android.R.layout.simple_spinner_item, items);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spin.setAdapter(adapter);
} catch (NullPointerException e) {
Toast.makeText(activity, "Can not load list. Check your connection", Toast.LENGTH_LONG).show();
e.printStackTrace();
} catch (Exception e) {
Toast.makeText(activity, "Can not load list. Check your connection", Toast.LENGTH_LONG).show();
e.printStackTrace();
}
super.onPostExecute(result);
if (dialog != null)
dialog.dismiss();
}
protected void onPreExecute() {
super.onPreExecute();
dialog.setTitle(title);
dialog.setMessage("Wait...");
dialog.setCancelable(false);
dialog.show();
}
@Override
protected String doInBackground(String... Strings) {
try {
Send_Request();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public void Send_Request() throws JSONException {
try {
String DataSendingTo = "http://www.example.com/AppRequest/" + where;
//HttpClient
HttpClient httpClient = new DefaultHttpClient();
//Post header
HttpPost httpPost = new HttpPost(DataSendingTo);
//Adding data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("authorized","001"));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// execute HTTP post request
HttpResponse response = httpClient.execute(httpPost);
BufferedReader reader;
try {
reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuilder builder = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
builder.append(line) ;
}
JSONTokener tokener = new JSONTokener(builder.toString());
JSONArray finalResult = new JSONArray(tokener);
items = new String[finalResult.length()];
// looping through All details and store in public String array
for(int i = 0; i < finalResult.length(); i++) {
JSONObject c = finalResult.getJSONObject(i);
items[i]=c.getString("data_name");
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
