我的应用中遇到AsyncTask问题。 AsyncTask位于SplashScreenAcivity.java。它使用json为MainActivity.java下载数据，同时显示启动画面。加载数据后，应用程序会显示MainActivity屏幕。但是，当我关闭互联网连接应用程序崩溃。而不是它，我想转移到MainActivity.java，并显示必须打开互联网连接的吐司。 SplashScreen.java在MainActivity中加载listView的数据。
SplashActivityScreen.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash_screen);
new DownloadData().execute();
}
private class DownloadData extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... voids) {
SyncHttpClient clientOne = new SyncHttpClient();
clientOne.get("https://api.themoviedb.org/3/tv/top_rated?api_key=d253f520df9cd868af7db8daaa0db8fb&language=en-US", new JsonHttpResponseHandler() {
@Override
public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
try {
tvseries0 = response.getJSONArray("results").getJSONObject(0).getString("name");
tvseries1 = response.getJSONArray("results").getJSONObject(1).getString("name");
tvseries2 = response.getJSONArray("results").getJSONObject(2).getString("name");
tvseries3 = response.getJSONArray("results").getJSONObject(3).getString("name");
tvseries4 = response.getJSONArray("results").getJSONObject(4).getString("name");
tvseries5 = response.getJSONArray("results").getJSONObject(5).getString("name");
tvseries6 = response.getJSONArray("results").getJSONObject(6).getString("name");
tvseries7 = response.getJSONArray("results").getJSONObject(7).getString("name");
tvseries8 = response.getJSONArray("results").getJSONObject(8).getString("name");
tvseries9 = response.getJSONArray("results").getJSONObject(9).getString("name");
tvseries10 = response.getJSONArray("results").getJSONObject(10).getString("name");
tvseries11 = response.getJSONArray("results").getJSONObject(11).getString("name");
tvseries12 = response.getJSONArray("results").getJSONObject(12).getString("name");
tvseries13 = response.getJSONArray("results").getJSONObject(13).getString("name");
tvseries14 = response.getJSONArray("results").getJSONObject(14).getString("name");
tvseries15 = response.getJSONArray("results").getJSONObject(15).getString("name");
tvseries16 = response.getJSONArray("results").getJSONObject(16).getString("name");
tvseries17 = response.getJSONArray("results").getJSONObject(17).getString("name");
tvseries18 = response.getJSONArray("results").getJSONObject(18).getString("name");
tvseries19 = response.getJSONArray("results").getJSONObject(19).getString("name");
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int statusCode, Header[] headers,Throwable e , JSONObject response) {
Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();
}
});
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
Intent i = new Intent(getApplicationContext(), MainActivity.class);
i.putExtra("tvseries0", tvseries0);
i.putExtra("tvseries1", tvseries1);
i.putExtra("tvseries2", tvseries2);
i.putExtra("tvseries3", tvseries3);
i.putExtra("tvseries4", tvseries4);
i.putExtra("tvseries5", tvseries5);
i.putExtra("tvseries6", tvseries6);
i.putExtra("tvseries7", tvseries7);
i.putExtra("tvseries8", tvseries8);
i.putExtra("tvseries9", tvseries9);
i.putExtra("tvseries10", tvseries10);
i.putExtra("tvseries11", tvseries11);
i.putExtra("tvseries12", tvseries12);
i.putExtra("tvseries13", tvseries13);
i.putExtra("tvseries14", tvseries14);
i.putExtra("tvseries15", tvseries15);
i.putExtra("tvseries16", tvseries16);
i.putExtra("tvseries17", tvseries17);
i.putExtra("tvseries18", tvseries18);
i.putExtra("tvseries19", tvseries19);
startActivity(i);
finish();
}
}
}
崩溃1
04-30 13:15:35.165 12349-12365/przemo.me.recommend.recommendme E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: przemo.me.recommend.recommendme, PID: 12349
java.lang.RuntimeException: An error occurred while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:318)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
Caused by: java.lang.RuntimeException: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at com.loopj.android.http.AsyncHttpResponseHandler.onUserException(AsyncHttpResponseHandler.java:304)
at com.loopj.android.http.AsyncHttpResponseHandler.handleMessage(AsyncHttpResponseHandler.java:395)
at com.loopj.android.http.AsyncHttpResponseHandler.sendMessage(AsyncHttpResponseHandler.java:401)
at com.loopj.android.http.AsyncHttpResponseHandler.sendFailureMessage(AsyncHttpResponseHandler.java:319)
at com.loopj.android.http.AsyncHttpRequest.run(AsyncHttpRequest.java:109)
at com.loopj.android.http.SyncHttpClient.sendRequest(SyncHttpClient.java:95)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1078)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1037)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:64)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:56)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:200)
at android.os.Handler.<init>(Handler.java:114)
at android.widget.Toast$TN.<init>(Toast.java:346)
at android.widget.Toast.<init>(Toast.java:101)
at android.widget.Toast.makeText(Toast.java:260)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData$1.onFailure(SplashScreenActivity.java:103)
at com.loopj.android.http.JsonHttpResponseHandler.onFailure(JsonHttpResponseHandler.java:233)
at com.loopj.android.http.AsyncHttpResponseHandler.handleMessage(AsyncHttpResponseHandler.java:359)
at com.loopj.android.http.AsyncHttpResponseHandler.sendMessage(AsyncHttpResponseHandler.java:401)
at com.loopj.android.http.AsyncHttpResponseHandler.sendFailureMessage(AsyncHttpResponseHandler.java:319)
at com.loopj.android.http.AsyncHttpRequest.run(AsyncHttpRequest.java:109)
at com.loopj.android.http.SyncHttpClient.sendRequest(SyncHttpClient.java:95)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1078)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1037)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:64)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:56)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
崩溃2
04-30 13:15:35.162 12349-12365/przemo.me.recommend.recommendme E/AsyncHttpRH: User-space exception detected!
java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:200)
at android.os.Handler.<init>(Handler.java:114)
at android.widget.Toast$TN.<init>(Toast.java:346)
at android.widget.Toast.<init>(Toast.java:101)
at android.widget.Toast.makeText(Toast.java:260)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData$1.onFailure(SplashScreenActivity.java:103)
at com.loopj.android.http.JsonHttpResponseHandler.onFailure(JsonHttpResponseHandler.java:233)
at com.loopj.android.http.AsyncHttpResponseHandler.handleMessage(AsyncHttpResponseHandler.java:359)
at com.loopj.android.http.AsyncHttpResponseHandler.sendMessage(AsyncHttpResponseHandler.java:401)
at com.loopj.android.http.AsyncHttpResponseHandler.sendFailureMessage(AsyncHttpResponseHandler.java:319)
at com.loopj.android.http.AsyncHttpRequest.run(AsyncHttpRequest.java:109)
at com.loopj.android.http.SyncHttpClient.sendRequest(SyncHttpClient.java:95)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1078)
at com.loopj.android.http.AsyncHttpClient.get(AsyncHttpClient.java:1037)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:64)
at przemo.me.recommend.recommendme.SplashScreenActivity$DownloadData.doInBackground(SplashScreenActivity.java:56)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
答案 0 :(得分：3)
您无法从非UI线程执行UI操作。就像在你的代码中一样，你在异步任务线程中显示Toast。
你应该替换
Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();
用这个
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();
}
});
答案 1 :(得分：1)
使用 -
SplashScreenActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();
}
});
答案 2 :(得分：1)
这是我多年前在Android Java中创建的服务器连接AsyncTask任务。后台任务成功运行。我用它来在后台更新我当时开发的App中的数据存储库。
public class DataExchangeStore extends Application {
public void startServerConnection(Context contextGlobal, Activity activityGlobal) {
this.contextGlobal = contextGlobal;
this.activityGlobal = activityGlobal;
connectTask = new ConnectTask();
connectTask.execute("");
}
private ConnectTask connectTask;
public class ConnectTask extends AsyncTask<String, String, TCPClient> {
@Override
protected TCPClient doInBackground(String... message) {
android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_BACKGROUND);
// we create a TCPClient object
mTcpClient = new TCPClient(new TCPClient.OnMessageReceived() {
@Override
// here the messageReceived method is implemented
public void messageReceived(ChatMessage message) {
// this method calls the onProgressUpdate
publishProgress(message.getMessage());
}
}, contextGlobal, activityGlobal);
mTcpClient.run();
return null;
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
System.err.println(values[0]);
// do your stuff here
}
}
导入是永久锁定活动的屏幕方向，使用纵向或横向指定 Android-Manifest 文件中的screenOrientation属性值：
<activity android:screenOrientation="portrait" />
答案 3 :(得分：0)
虽然以前的答案没有错，但是使用runOnUiThread()跳出AsyncTask中的后台线程并不是一个好习惯。你有onPostExecute()方法。
您应该做的是将结果对象传递给onPostExecute()。该对象将封装结果状态（即：错误或成功）和接收的实际数据。然后在onPostExecute()中检查结果状态并在状态为错误时显示Toast。
并帮自己一个忙，用List<TvSerie>替换你的20个TvSerie对象，并在你的AsyncTask中循环填充列表。
有关如何正确使用它的详细信息，请参阅the AsyncTask documentation。