Question

我设置了ProgressDialog，但我不会解雇它！它只是继续加载消息，不会结束。我认为我做得对，在onPreExecute设置了展示消息，将dismiss设置为onPostExecute，但有些设置如何无效

继承我的代码：

public class MainActivity extends Activity {

//String[] imgUrls = {getString(R.string.uncc_main_thumb),getString(R.string.football_main_thumb,getString(R.string.ifest_main_thumb),getString(R.string.commencement_main_thumb))};
String[] imgUrls={"http://farm5.staticflickr.com/4113/4843614620_c541de5a5c_m.jpg",
                  "http://farm8.staticflickr.com/7265/8151547298_85e60e7368_m.jpg",
                  "http://farm9.staticflickr.com/8054/8414075899_e87a74407b_m.jpg",
                  "http://farm9.staticflickr.com/8210/8277674769_7d1245dbf1_m.jpg"};
ProgressDialog progressDialog;
ImageView iv1,iv2,iv3,iv4;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    iv1 =(ImageView) findViewById(R.id.imageView1);
    iv2 =(ImageView) findViewById(R.id.imageView2);
    iv3 =(ImageView) findViewById(R.id.imageView3);
    iv4 =(ImageView) findViewById(R.id.imageView4);

    for (String imgUrl : imgUrls) {
        new DownLoadImages().execute(imgUrl);
    }
}

private class DownLoadImages extends
AsyncTask<String, Void, Bitmap> {
    @Override
        protected Bitmap doInBackground(String... params) {
        String imgUrl = params[0];
        Bitmap image = null;
        try {
            URL url = new URL(imgUrl);
            image = BitmapFactory.decodeStream(url.openStream());
            } catch (MalformedURLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        return image;
}

       @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // show the loading message while downloading the image

            ProgressDialog.show(MainActivity.this, null, "Loading");
        }

       @Override
       protected void onPostExecute(Bitmap result) {

           if (result == null) {
               result = ((BitmapDrawable) getResources().getDrawable(
                       R.drawable.not_found)).getBitmap();
            }

           //ImageView imageViewToBeAdded = new ImageView(getBaseContext());
          // imageViewToBeAdded.setLayoutParams(new LayoutParams(
            //     LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
          // imageViewToBeAdded.setPadding(5, 5, 5, 5);

           iv1.setImageBitmap(result);
           progressDialog.dismiss();

}
}

}

Answer 1

您没有创建ProgressDialog的实例。

替换

ProgressDialog.show(MainActivity.this, null, "Loading");

使用

progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Loading");

Answer 2

使用progressDialog代替ProgressDialog来调用ProgressDialog的show方法：

progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setCancelable(true);
progressDialog.setMessage("Loading...");

由于您使用ProgressDialog调用show方法但尝试使用progressDialog实例解雇，因此发生了问题。

Answer 3

在onPreExecute中，你使用className ProgressDialog.show这是一个静态方法，在onPostExecute中你实际上正在使用你的对象来阻止它。

使用你的对象在onPreExecute中启动它，它会起作用。

Answer 4

实例化对话框并保存参考：

progressDialog = ProgressDialog.show(MainActivity.this, null, "Loading");

ProgressDialog解雇不起作用

4 个答案: