Question

我正在尝试在我的片段中放入progressDialog，这样我的应用程序在每个操作之间感觉更顺畅。我遇到的问题是主线程在异步线程修改它之前返回视图。在切换到这个方法之前，我正在做一个Thread.join（）。

    public class MyFragment extends Fragment {
    public View onCreateView(LayoutInflater inflater,ViewGroup container, Bundle args) {
    mLLayout = new LinearLayout(getActivity()); 
    mLLayout.setPadding(0, 0, 0, 0);
    mLLayout.setOrientation(LinearLayout.VERTICAL);
    mScroll = new ScrollView(getActivity().getApplicationContext());
    mScroll.setVerticalScrollBarEnabled(true);
    mScroll.addView(mLLayout);

    new AsyncCaller().execute();

    return mScroll;
}

private class AsyncCaller extends AsyncTask<Void, Void, Void>
{
    ProgressDialog nDialog = new ProgressDialog(getActivity());

    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();

        //this method will be running on UI thread
        nDialog = new ProgressDialog(getActivity());
        nDialog.setMessage("Loading..");
        nDialog.setTitle("Checking Network");
        nDialog.setIndeterminate(false);
        nDialog.setCancelable(true);
        nDialog.show();
    }
    @Override
    protected Void doInBackground(Void... params) 
    {
        //Doing http requests and modifying views
        return null;
    }

    @Override
    protected void onPostExecute(Void result) 
    {
        super.onPostExecute(result);

        //this method will be running on UI thread

        nDialog.dismiss();
    }
}
...
}

我无法在不阻塞主线程的情况下找到一个解决方案，并且同样没有看到progressDialog，而是有一个很大的延迟。另外，我从未看到我的代码进入“onPostExecute（）”。

提前感谢您的帮助！

Answer 1

直接从我已经完成的应用程序，这段代码应该有所帮助：

ProgressBar mProgress = (ProgressBar) findViewById(R.id.progressBar);
private float mProgressStatus = 0;
private Handler mHandler = new Handler();

private void startProgressBar()
{
    new Thread(new Runnable()
    {
        @Override
        public void run()
        {
            while (mProgressStatus < 100)
            {
                try
                {
                    Thread.sleep(1000);
                }
                catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
                mProgressStatus += 1.3;
                mHandler.post(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        mProgress.setProgress((int) mProgressStatus);
                    }
                });
            }
        }
    }).start();
}

片段在线程结束之前返回视图

1 个答案: