java - 应用程序崩溃而无法执行 AsyncTask

Question

我的应用程序中的 AsyncTask 存在问题。 AsyncTask 位于 SplashScreenAcivity.java 中。它使用 MainActivity.java 的 json 下载数据，同时显示启动屏幕。加载数据后，应用程序将显示 MainActivity 屏幕。但是，当我关闭互联网连接时，应用程序崩溃。相反，我想移动到 MainActivity.java 并显示必须打开互联网连接。 SplashScreen.java 为 MainActivity 中的 listView 加载数据。

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)

Answer 1

您不能从非 UI 线程执行 UI 操作。就像在您的代码中一样，您在异步任务线程中显示 Toast。

你应该更换

Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();     

有了这个

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(SplashScreenActivity.this, "Turn on the internet and swipe to refresh.", Toast.LENGTH_SHORT).show();     
        }
    });