Question

我正在尝试使用下面的代码在弹出窗口中显示图像。基本上有一个音频文件列表，当我点击它时，会出现一个弹出窗口，显示其专辑封面（这是我期望它做的）。但是，应用程序崩溃了。 LogCat提供了NullPointerException - 我确信这只是因为ImageView。这是我的代码：

public class MainActivity extends SherlockListActivity {
    Uri sourceUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    @SuppressWarnings("deprecation")
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        
        @SuppressWarnings("unused")
        ActionBar ab = getSupportActionBar();
        String[] from = {MediaStore.MediaColumns.TITLE,MediaStore.MediaColumns.DATA};
        int[] to = {android.R.id.text1};

        CursorLoader cursorLoader = new CursorLoader(this,sourceUri,null,null,null,MediaStore.Audio.Media.TITLE);
        Cursor cursor = cursorLoader.loadInBackground();
        startManagingCursor(cursor);
        ListAdapter adapter = new SimpleCursorAdapter(this,android.R.layout.simple_list_item_1,cursor,from,to,CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
        setListAdapter(adapter);

    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        Cursor cl = ((SimpleCursorAdapter)l.getAdapter()).getCursor();
        cl.moveToPosition(position);
        String loc = cl.getString(cl.getColumnIndex(MediaStore.MediaColumns.DATA));
        File f = new File(loc);
        MusicMetadataSet mmds;
        try {
            mmds = new MyID3().read(f);
            if(mmds!=null){
            MusicMetadata mmd =  (MusicMetadata)mmds.getSimplified();
            String s = mmd.getArtist() +"-"+mmd.getSongTitle();
            Toast.makeText(this,s,Toast.LENGTH_SHORT).show();
            @SuppressWarnings("unchecked")
            Vector<ImageData> img = mmd.getPictureList();
                if(!img.isEmpty()){
                    byte[] imgData = img.get(0).imageData;
                    Bitmap bmp = BitmapFactory.decodeByteArray(imgData, 0, imgData.length);
                    LayoutInflater layoutInflater=(LayoutInflater)getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);  
                    View popupView = layoutInflater.inflate(R.layout.popup, null);
                    final PopupWindow popupWindow = new PopupWindow(popupView,100,100);

                                /**** PROBLEM BECAUSE OF THIS ************/
                    ImageView iv = (ImageView)findViewById(R.id.imageView);
                    iv.setImageBitmap(bmp);



                    popupWindow.showAtLocation(popupView, Gravity.CENTER, 0, 0);
                    Button btnOk = (Button)popupView.findViewById(R.id.btnOk);
                    btnOk.setOnClickListener(new OnClickListener() 
                    {                    
                        @Override
                        public void onClick(View v) 
                        {
                            popupWindow.dismiss();  //dismissing the popup
                        }
                    });


                }
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

我该如何解决？这是我的popup.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:orientation="vertical"
  android:background="#90FFFFFF"
  android:layout_height="wrap_content">

  <TextView
      android:layout_width="fill_parent"
      android:text="@string/art"
      android:textColor="#000000"
      android:gravity="center"
      android:textStyle="bold"
      android:layout_height="wrap_content">
  </TextView>
  <ImageView
      android:layout_width="fill_parent"
      android:id="@+id/imageView"
      android:contentDescription="@string/art"
      android:layout_height="wrap_content"
      />
  <Button
      android:layout_width="fill_parent"
      android:id="@+id/btnOk"
      android:text="@string/ok"
      android:layout_height="wrap_content">
  </Button>
</LinearLayout>

问题是，TextView和Button看起来很好。仅ImageView奇怪地出现这个问题！请帮助，这让我疯了。

Answer 1

更改您的代码

 ImageView iv = (ImageView)findViewById(R.id.imageView);

到

 ImageView iv = (ImageView)popupView.findViewById(R.id.imageView);

应用程序因ImageView NullPointerException而崩溃

1 个答案: