Question

我需要向用户显示进度消息。但我无法显示。这是我的代码。我的代码出了什么问题。请指导我。

public class MyProgressDemo extends Activity {
/** Called when the activity is first created. */

private Button clickBtn;
public ProgressDialog progressDialog;
Handler handler = new Handler();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    clickBtn = (Button) findViewById(R.id.Button01);
    clickBtn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            progressDialog = ProgressDialog.show(MyProgressDemo.this, "",
                    "Please Wait");
            processThread();

        }

    });

}

protected void processThread() {

    handler.post(new Runnable() {

        @Override
        public void run() {
            longTimeMethod();
            UI();
            progressDialog.dismiss();
        }
    });

}

private void longTimeMethod() {
    try {
        String strMethod = "MethodName";
        String strUrl = "url";
        String strResponse = WebserviceCall.Mobileaappstore(strUrl,
                strMethod);
        Log.d("RES", strResponse);
    } catch (Exception e) {
        Log.e("Exc", e.getMessage());
    }

}

private void UI() {
    TextView tv = new TextView(this);
    tv.setText("This is new UI");
    setContentView(tv);
}

}

Answer 1

方法Handler.post，在UI线程中产生一个线程，所以你的longTimeMethod（）;将在UI线程中运行，阻止它。你应该这样做：

protected void processThread() {
    Thread t = new Thread(){
       longTimeMethod();
       // Sends message to the handler so it updates the UI
       handler.sendMessage(Message.obtain(mHandler, THREAD_FINISHED));
    }
    // Spawn the new thread as a background thread
    t.start
}

您的处理程序应如下所示，以便管理消息

private Handler mHandler = new Handler() {
    @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            switch (msg.what) {
            case THREAD_FINISHED:
                       UI();
                       progressDialog.dismiss();
                       break    
                }   
        }
};

您可以使用此解决方案或AsynTask，这取决于您，两者都有效。选择最适合你的那个。

Answer 2

您尝试做的完全适合Android中的AsyncTask framework。尝试通过继承AsyncTask类来实现它，负责将所有与UI相关的东西放在onPreExecute / onPostExecute方法中，并在doInBackground方法中使用长时间方法。

如果您需要活动中的内容，请将其作为参数传递给AsyncTask的构造函数，或者将AsyncTask作为活动的内部类。

Answer 3

要添加到MarvinLabs的帖子，您可以像这样显示和解除ProgressDialog。

private class SubmitCommentTask extends AsyncTask<String, Void, Void> {
    ProgressDialog dialog;
    protected Void doInBackground(String... params) {
        // Your long running code here
        return null;
    }

    protected void onPreExecute() {
        dialog = ProgressDialog.show(DetailsInfo.this, "Submitting Comment", "Please wait for the comment to be submitted.", true);
    }

    protected void onPostExecute(Void Result)
    {
        dialog.dismiss();
    }
}

如何在Android中显示进度对话框？

3 个答案: