Question

当我从第一个活动类跳过第二个活动类时，我将在第二个活动中开始对某个图像进行图像处理，然后直到新图像进入屏幕我才开始进度条，然后在新图像进入屏幕时结束。我怎么能这样做？

Answer 1

使用ProgreaaDialog和AsyncTask。你会得到你的灵魂在doBackInGroundProcess中使用AsyncTask进行图像处理。并在doPostExecute（）中退出或取消进度对话框

查看示例代码。要启动AsyncTsk，请使用您要进行图像处理的活动中的new ProgressTask().execute(null);。

    private class ProgressTask extends AsyncTask<String, Void, Boolean> {
        private ProgressDialog dialog;
        List<Message> titles;
        private ListActivity activity;
        //private List<Message> messages;
        public ProgressTask(ListActivity activity) {
            this.activity = activity;
            context = activity;
            dialog = new ProgressDialog(context);
        }



        /** progress dialog to show user that the backup is processing. */

        /** application context. */
        private Context context;

        protected void onPreExecute() {
            this.dialog.setMessage("Progress start");
            this.dialog.show();
        }

            @Override
        protected void onPostExecute(final Boolean success) {
                List<Message> titles = new ArrayList<Message>(messages.size());
                for (Message msg : messages){
                    titles.add(msg);
                }
                MessageListAdapter adapter = new MessageListAdapter(activity, titles);
                activity.setListAdapter(adapter);
                adapter.notifyDataSetChanged();

                if (dialog.isShowing()) {
                dialog.dismiss();
            }

            if (success) {
                Toast.makeText(context, "OK", Toast.LENGTH_LONG).show();
            } else {
                Toast.makeText(context, "Error", Toast.LENGTH_LONG).show();
            }
        }

        protected Boolean doInBackground(final String... args) {
            try{    
                BaseFeedParser parser = new BaseFeedParser();
                messages = parser.parse();


                return true;
             } catch (Exception e){
                Log.e("tag", "error", e);
                return false;
             }
          }


    }

}

拥有look here

Answer 2

尝试使用Async任务，如下所示：

try{
class test extends AsyncTask{


     TextView tv_per;
     int mprogress;

    Dialog UpdateDialog = new Dialog(ClassContext);

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        mprogress = 0;

        UpdateDialog.setTitle(getResources().getString(R.string.app_name));
        UpdateDialog.setContentView(R.layout.horizontalprogressdialog);
        TextView dialog_message =  (TextView)UpdateDialog.findViewById(R.id.titleTvLeft);
        tv_per = (TextView)UpdateDialog.findViewById(R.id.hpd_tv_percentage);
        dialog_message.setText(getResources().getString(R.string.dialog_retrieving_data));
        dialog_message.setGravity(Gravity.RIGHT);
        UpdateDialog.setCancelable(false);
        UpdateDialog.show();
        super.onPreExecute();
    }



    @Override
    protected void onProgressUpdate(Object... values) {
        // TODO Auto-generated method stub
        ProgressBar update = (ProgressBar)UpdateDialog.findViewById(R.id.horizontalProgressBar);
        update.setProgress((Integer) values[0]);
        int percent =  (Integer) values[0];
        if(percent>=100)
        {
            percent=100;
        }
        tv_per = (TextView)UpdateDialog.findViewById(R.id.hpd_tv_percentage);
         tv_per.setText(""+percent);
    }



    @Override
    protected Object doInBackground(Object... params) {
        // TODO Auto-generated method stub
        //your code
}

        super.onPostExecute(result);
        UpdateDialog.dismiss();
    }

 }
 new test().execute(null);

 }
catch(Exception e)
{
 e.printStackTrace();
}

Answer 3

试试这种方式首先初始化您的ProgressDialog

 progressDialog = ProgressDialog.show(this, "", "Trying to ...");

然后启动一个新线程，您可以在其中编写需要执行的代码最后在处理程序中处理代码并结束progessDialog

Answer 4

这是一种方法，在调用时启动进度条

private void downloadText(String urlStr) {

    final String url = urlStr;
     progressDialog = ProgressDialog.show(this, "", "Trying to register...");
    Log.i("First string", urlStr);
try{
    new Thread () {
        public void run() {
            int BUFFER_SIZE = 2000;
            InputStream in = null;
            try{
           msg = Message.obtain();
            msg.what=1;
            }catch(Exception e)
            {
            }

            try {
                in = openHttpConnection(url);
           InputStreamReader isr = new InputStreamReader(in);
                int charRead;
                  text = "";
                  char[] inputBuffer = new char[BUFFER_SIZE];

                      while ((charRead = isr.read(inputBuffer))>0)
                      {                    
                          //---convert the chars to a String---
                          String readString = 
                          String.copyValueOf(inputBuffer, 0, charRead);                    
                          text += readString;
                          inputBuffer = new char[BUFFER_SIZE];
                      }
                     Bundle b = new Bundle();
                        b.putString("text", text);
                        msg.setData(b);
                      in.close();

            }catch (Exception e) {

            //////////////////////////////////////  
                e.printStackTrace();
            }
            try{
            messageHandler.sendMessage(msg);
            }catch(Exception e)
            {
            }
        }
    }.start();
}catch(Exception e)
{

}

}

这是处理程序代码

private Handler messageHandler = new Handler() {


    public void handleMessage(Message msg) {
        try{
        super.handleMessage(msg);
        switch (msg.what) {

        case 1:

{ 打破; } } progressDialog.dismiss（）; } catch（例外e） {

如何在android中动态启动和完成progressBar

4 个答案: