标签: android-asynctask

除非我删除这个,否则我会收到例外:

机器人:targetSdkVersion = "15"

我在SO的另一个帖子中找到了.

但是,我已经在那里使用了targetSdkVersion运行了几天.这是我的代码:

public class MainActivity extends BaseActivity {
    private TextView textView;
    private String url = "http://www.backcountryskiers.com/sac/sac-full.html";
    private ImageView image;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.todaysReport);
        image = (ImageView) findViewById(R.id.dangerRose);

        fetcher task = new fetcher();
        task.execute();
    }

    public static Bitmap getBitmapFromURL(String src) {
        try {
            Log.e("src", src);
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url
                    .openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();
            Bitmap myBitmap = BitmapFactory.decodeStream(input);
            Log.e("Bitmap", "returned");
            return …

我正在开发一个Android应用程序,它使用在.ashx请求处理程序中开发的Web服务.

• 应用程序等待很多,并在第一次启动aap时显示黑屏.
• 有时它会给出内存虚拟机预算错误.

这是一些代码.

 public class Home extends Activity implements AdapterView.OnItemClickListener {
        /** Called when the activity is first created. */

        Context context = Home.this;
        HashMap<String, String> map = new HashMap<String, String>();
        ArrayList<String> BookTitle = new ArrayList<String>();
        ArrayList<String> BookCoverPhotos = new ArrayList<String>();

        URL bookImageURL = null;
        Bitmap bitMapImage = null;

        View homeTabLayout;
        View reviewLayout;
        ArrayList<String> ImageUrl = new ArrayList<String>();
        ImageButton btnBack;


        // XML Parsing
        ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();

        // All static variables
        static final String URL = …

是否可以将文件传递给AsyncTask？像这样？

public class UploadImagesTask extends AsyncTask<String, String, File> {
    @Override
    protected File doInBackground(String... params) {

这样做我会访问该文件吗？

params[2]

我正在扩展AsyncTask并在我的doInBackground()中使用findViewById得到一个按钮视图,当我调用button.performClick()时,我的应用程序崩溃了.

知道为什么吗？

这是logcat:

E/AndroidRuntime(604): FATAL EXCEPTION: AsyncTask #2
E/AndroidRuntime(604): java.lang.RuntimeException: An error occured while executing doInBackground()
E/AndroidRuntime(604):  at android.os.AsyncTask$3.done(AsyncTask.java:278)
E/AndroidRuntime(604):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
E/AndroidRuntime(604):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
E/AndroidRuntime(604):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
E/AndroidRuntime(604):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
E/AndroidRuntime(604):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
E/AndroidRuntime(604):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
E/AndroidRuntime(604):  at java.lang.Thread.run(Thread.java:856)
E/AndroidRuntime(604): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
E/AndroidRuntime(604):  at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4039)
E/AndroidRuntime(604):  at android.view.ViewRootImpl.playSoundEffect(ViewRootImpl.java:3610)
E/AndroidRuntime(604):  at android.view.View.playSoundEffect(View.java:13103)
E/AndroidRuntime(604):  at android.view.View.performClick(View.java:3510)

我有一个Async正在运行以从我创建的页面获取数据.它得到的文本很好,但当我尝试通过另一个类从图像src获取图像时,应用程序强制关闭.以下是强制关闭的代码:

public class FullReportActivity extends NavigationActivity {
    private TextView textView;
    private String url = "http://www.backcountryskiers.com/sac/sac-full.html";
    private ImageView ivDangerRose;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        // tell which region this covers
        getSupportActionBar().setSubtitle("...from Sierra Avalanche Center");
        setContentView(R.layout.activity_fullreport);
        textView = (TextView) findViewById(R.id.todaysReport);
        ivDangerRose = (ImageView) findViewById(R.id.dangerRose);
        fetcher task = new fetcher();
        task.execute();
    }

    // GET THE IMAGE and RETURN IT
    public static Bitmap getBitmapFromURL(String src) {
        try {
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url
                    .openConnection();
            connection.setDoInput(true);
            connection.connect(); …

我有一个非常简单的应用程序,主要威胁启动2 AsyncTasks.2个AsyncTasks几乎相同,这是我的一个AsyncTasks的代码:

private class waitPlayer extends AsyncTask<Integer, Integer, Void> {

        @Override
        protected Void doInBackground(Integer... params) {

            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                       CreateLog.addToLog(e.toString);
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            // Update your layout here
            super.onPostExecute(result);
            setCanPlay(true, lastPlayerPlayed);
        }

        @Override
        protected void onProgressUpdate(Integer... progress) {

             //progress_p1.setProgress((int) progress[0]);
             //progress_p2.setProgress((int) progress[0]);

        }
    }

AsyncTask唯一能做的就是等待200ms,完成后它会调用一个方法.该方法将再次调用AsyncTask.另一个AsyncTask几乎相同,只等待3000ms并调用另一种方法.

问题是,在我添加第二个AsyncTask之后,我的应用程序变得很慢.它在AsyncTasks运行时冻结几秒钟.我的Logcat说充满了垃圾收集器通知.

我的手机没有冻结,只有应用程序.我有大约200mb的免费RAM.

01-06 19:26:00.695: W/ActivityThread(25739): Application com.obattech.twoplayergame is waiting for the debugger on port 8100...
01-06 19:26:00.705: I/System.out(25739): Sending WAIT chunk
01-06 19:26:00.710: …

我的应用程序中有一个AsyncTask类,但我注意到无论传递给onPostExecute函数的结果是什么,它仍会指示应用程序转到else {},即使它完全符合if语句.为什么会这样？

这是我正在运行的AsyncTask:

class CheckPassword extends AsyncTask<String, String, String>{

@Override
protected void onPreExecute() {
    super.onPreExecute();
    pDialog = new ProgressDialog(ChooseTable.this);
    pDialog.setMessage("Checking Password. Please wait...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show();
}

@Override
protected String doInBackground(String... p) {
    String password = p[0];
    int success;
    String access = "";

    try {
        // Building Parameter
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("password", password));

        //ipaddress of server

        Intent i = getIntent();
        Bundle b = i.getExtras();
        ipaddress = b.getString("IP_Address");

        if(ipaddress != "" || ipaddress != "...:")
        {
            // single …

我是android的新手,我想获取联系人并在列表视图中显示.这是我在asynctask.please中获取联系人的代码,帮助我们在获取每个联系人后更新列表视图.

protected Void doInBackground(Void... params) {
         ContentResolver cr = ReadContactsActivity.this.getContentResolver();
         Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI,
                null, null, null, null);

         if (cur.getCount() > 0) {
             while (cur.moveToNext()) {
                 String id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
                 String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
                 if (Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) {
                     Cursor pCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,null,
                                            ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = ?",
                                            new String[]{id}, null);
                     while (pCur.moveToNext()) {
                           String phone = pCur.getString(
                                  pCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                        //li.add("Name:"+name+",Number:"+phone);
                           publishProgress("Name:"+name+",Number:"+phone);
                     }
                     pCur.close();
                     }
                 }
             }
        return null;
    }


    // A callback method executed on UI thread, invoked by the publishProgress() …

在这里第一次发布问题.刚开始编程和编码我的第一个应用程序

我有一个Application类文件,其方法为fetchUpdates():

public synchronized void fetchUpdates() {
    String[] mURLs = getURLs();
    new DownloadJSONData().execute(mURLs[0], mURLs[1]);
}

DownloadJSONData是asyncTask从服务器获取更新,该onPostExecute方法使用服务器中的JSON数组更新sqlite数据库.

应用程序的不同组件(小部件和活动)调用此方法以从服务器获取更新以更新数据库.

问题:synchronized方法是否在与UI线程不同的线程上运行？如果是这样,DownloadJSONData将同步fetchUpdates()方法中的代码移动到右边应该没有问题吗？如果在连接服务器或从服务器下载数据时存在滞留,它不应该阻止UI线程吗？

动机:我正在尝试更改fetchUpdates()方法以返回指示数据库是否已更新的布尔值.然而,因为它现在是(我认为)fetchUpdates()方法之前完成asyncTask的onPostExecute方法,因此,fetchUpdates()方法不能指明呼叫是否DownloadJSONData()更新数据库.fetchUpdates()如果在调用后更新数据库,我需要调用方法的应用程序组件以不同的方式运行.

PS因为我刚接触编程简单而详细的解释会非常有用.

谢谢!

我正试图在我的应用程序中解析json:

所以首先我为我的Android应用程序创建了常量类,它为app.config提供了大约6个变量:

(等级:1)

public class Constants{

    // url to make request
    public static String url = "http://server.com/";

    // JSON Node names
    public static final String TAG_CONTACTS = "contacts";
    public static final String TAG_ID = "id";
    public static final String TAG_NAME = "name";
    public static final String TAG_EMAIL = "email";
    public static final String TAG_ADDRESS = "address";
    public static final String TAG_GENDER = "gender";

}

现在我想在不同的类中使用它,所以我继续创建了不同的类:

(等级:2)

    public class ReadFiles{

        public void readConstant(){
       //appConfig is JSONArray
        JSONArray appConfig = null;
       // …