Domanda
I have an app that reads an external database and extracts results to fill a ListView, whose row consists of a TextView and a Button. But when I changed the ordinary Button to an ImageButton, the app immediately stops after launching. My .xml for each row is as follows:
https://stackoverflow.com/questions/23333592
italiano
english
français
española
中国
日本の
العربية
Deutsch
한국어
Português
Russian<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/RelativeLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageButton
android:id="@+id/listButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="41dp"
android:layout_marginTop="16dp"
android:background="@null"
android:src="@drawable/ciplus" />
<TextView
android:id="@+id/listText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/listButton"
android:layout_marginRight="56dp"
android:layout_toLeftOf="@+id/listButton"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
</RelativeLayout>
Next to the ImageButton tag, I also get a warning saying: [Accessibility] Missing contentDescription attribute on image. I'm not sure whether it's the cause.
If it's just a Button, the program works fine. I don't know why changing it to ImageButton causes the problem. Thanks in advance.
Here's the java code:
public class MainActivity extends Activity {
static final private String LOG_TAG = "main";
private ArrayList<Content> aList;
private class Content{
Content() {};
public String title;
public String url;
}
private class MyAdapter extends ArrayAdapter<Content>{
int resource;
public MyAdapter(Context _context, int _resource, List<Content> titles) {
super(_context, _resource, titles);
resource = _resource;
// this.context = _context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LinearLayout newView;
final Content content = getItem(position);
// Inflate a new view if necessary.
if (convertView == null) {
newView = new LinearLayout(getContext());
String inflater = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater vi = (LayoutInflater) getContext().getSystemService(inflater);
vi.inflate(resource, newView, true);
} else {
newView = (LinearLayout) convertView;
}
// Fills in the view.
TextView tv = (TextView) newView.findViewById(R.id.listText);
Button b = (Button) newView.findViewById(R.id.listButton);
tv.setText(content.title);
// Sets a listener for the button, and a tag for the button as well.
b.setTag(Integer.toString(position));
b.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Reacts to a button press.
Intent intent = new Intent(MainActivity.this, WebPage.class);
Bundle bundle = new Bundle();
bundle.putString("URL", content.url);
intent.putExtras(bundle);
startActivity(intent);
}
});
return newView;
}
}
class MyAsyncTask extends AsyncTask<String, String, String> {
private ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
InputStream inputStream = null;
String result = "";
Content content;
protected void onPreExecute() {
super.onPreExecute();
progressDialog.setMessage("Downloading the news...");
progressDialog.show();
progressDialog.setOnCancelListener(new OnCancelListener() {
public void onCancel(DialogInterface arg0) {
MyAsyncTask.this.cancel(true);
}
});
}
@Override
protected String doInBackground(String... params) {
String url_select = params[0];
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
try {
// Set up HTTP post
// HttpClient is more then less deprecated. Need to change to URLConnection
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// Read content & Log
inputStream = httpEntity.getContent();
} catch (UnsupportedEncodingException e1) {
Log.e("UnsupportedEncodingException", e1.toString());
e1.printStackTrace();
} catch (ClientProtocolException e2) {
Log.e("ClientProtocolException", e2.toString());
e2.printStackTrace();
} catch (IllegalStateException e3) {
Log.e("IllegalStateException", e3.toString());
e3.printStackTrace();
} catch (IOException e4) {
Log.e("IOException", e4.toString());
e4.printStackTrace();
}
// Convert response to string using String Builder
try {
BufferedReader bReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"), 8);
StringBuilder sBuilder = new StringBuilder();
String line = null;
while ((line = bReader.readLine()) != null) {
sBuilder.append(line + "\n");
}
inputStream.close();
result = sBuilder.toString();
} catch (Exception e) {
Log.e("StringBuilding & BufferedReader", "Error converting result " + e.toString());
}
return result;
} // protected Void doInBackground(String... params)
protected void onPostExecute(String result) {
//parse JSON data
try {
super.onPostExecute(result);
Log.i(LOG_TAG, result);
JSONObject object = new JSONObject(result);
JSONArray jArray = object.getJSONArray("sites");
for(int i=0; i < jArray.length(); i++) {
JSONObject jObject = jArray.getJSONObject(i);
content = new Content();
if (jObject.has("title") && jObject.has("url")){
content.title = jObject.getString("title");
content.url = jObject.getString("url");
aList.add(content);
aa.notifyDataSetChanged();
}
} // End Loop
progressDialog.dismiss();
} catch (JSONException e) {
// progressDialog.dismiss();
Log.e("JSONException", "Error: " + e.toString());
}
} // protected void onPostExecute(String result)
}
private MyAdapter aa;
private MyAsyncTask loadTask;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loadTask = new MyAsyncTask();
loadTask.execute("http://luca-ucsc.appspot.com/jsonnews/default/news_sources.json");
aList = new ArrayList<Content>();
aa = new MyAdapter(this, R.layout.list_element, aList);
ListView myListView = (ListView) findViewById(R.id.listView1);
myListView.setAdapter(aa);
aa.notifyDataSetChanged();
}
public void refresh(View v){
if (loadTask.getStatus() == AsyncTask.Status.FINISHED){
aList.clear();
aa.notifyDataSetChanged();
new MyAsyncTask().execute("http://luca-ucsc.appspot.com/jsonnews/default/news_sources.json");
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Here's the logcat info roughly from lunching to stop:
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 3, Width = 6, current total allocated size out of MAX(1024) = 178
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 7, Width = 6, current total allocated size out of MAX(1024) = 186
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 2, current total allocated size out of MAX(1024) = 194
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 15, Width = 9, current total allocated size out of MAX(1024) = 198
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 8, Width = 7, current total allocated size out of MAX(1024) = 209
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 218
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 14, current total allocated size out of MAX(1024) = 231
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 8, Width = 8, current total allocated size out of MAX(1024) = 247
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 16, Width = 2, current total allocated size out of MAX(1024) = 257
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 0, Width = 0, current total allocated size out of MAX(1024) = 261
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 3, Width = 3, current total allocated size out of MAX(1024) = 263
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 13, current total allocated size out of MAX(1024) = 268
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 3, Width = 4, current total allocated size out of MAX(1024) = 283
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 14, current total allocated size out of MAX(1024) = 289
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 8, current total allocated size out of MAX(1024) = 305
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 4, Width = 3, current total allocated size out of MAX(1024) = 315
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 8, current total allocated size out of MAX(1024) = 320
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 2, Width = 7, current total allocated size out of MAX(1024) = 330
04-28 00:09:03.859: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 2, Width = 7, current total allocated size out of MAX(1024) = 339
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 6, Width = 8, current total allocated size out of MAX(1024) = 348
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 15, Width = 9, current total allocated size out of MAX(1024) = 358
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 7, current total allocated size out of MAX(1024) = 369
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 9, current total allocated size out of MAX(1024) = 378
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 7, Width = 7, current total allocated size out of MAX(1024) = 389
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 10, current total allocated size out of MAX(1024) = 398
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 9, current total allocated size out of MAX(1024) = 410
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 9, current total allocated size out of MAX(1024) = 421
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 3, current total allocated size out of MAX(1024) = 432
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 3, current total allocated size out of MAX(1024) = 437
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 3, Width = 5, current total allocated size out of MAX(1024) = 442
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 9, current total allocated size out of MAX(1024) = 449
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 10, Width = 5, current total allocated size out of MAX(1024) = 460
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 15, Width = 9, current total allocated size out of MAX(1024) = 467
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 10, Width = 14, current total allocated size out of MAX(1024) = 478
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 18, Width = 5, current total allocated size out of MAX(1024) = 494
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 18, Width = 5, current total allocated size out of MAX(1024) = 13
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 9, current total allocated size out of MAX(1024) = 494
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 2, Width = 9, current total allocated size out of MAX(1024) = 505
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 10, Width = 9, current total allocated size out of MAX(1024) = 516
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 9, current total allocated size out of MAX(1024) = 527
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 9, current total allocated size out of MAX(1024) = 538
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 8, current total allocated size out of MAX(1024) = 549
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 6, current total allocated size out of MAX(1024) = 559
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 10, Width = 14, current total allocated size out of MAX(1024) = 567
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 11, Width = 8, current total allocated size out of MAX(1024) = 583
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 9, current total allocated size out of MAX(1024) = 593
04-28 00:09:03.869: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 10, Width = 8, current total allocated size out of MAX(1024) = 604
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 3, current total allocated size out of MAX(1024) = 614
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 619
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 15, Width = 8, current total allocated size out of MAX(1024) = 632
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 9, Width = 8, current total allocated size out of MAX(1024) = 642
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 9, current total allocated size out of MAX(1024) = 652
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 9, current total allocated size out of MAX(1024) = 663
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 9, current total allocated size out of MAX(1024) = 674
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 685
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 18, Width = 4, current total allocated size out of MAX(1024) = 698
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 18, Width = 4, current total allocated size out of MAX(1024) = 20
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 698
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 16, current total allocated size out of MAX(1024) = 711
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 19, Width = 6, current total allocated size out of MAX(1024) = 729
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 19, Width = 6, current total allocated size out of MAX(1024) = 26
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 729
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 14, current total allocated size out of MAX(1024) = 742
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 758
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 11, current total allocated size out of MAX(1024) = 771
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 10, current total allocated size out of MAX(1024) = 784
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 15, Width = 12, current total allocated size out of MAX(1024) = 796
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 10, current total allocated size out of MAX(1024) = 810
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 11, current total allocated size out of MAX(1024) = 822
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 11, current total allocated size out of MAX(1024) = 835
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 14, Width = 10, current total allocated size out of MAX(1024) = 848
04-28 00:09:03.879: E/OpenGLRenderer(14018): HUAWEI_DEBUG: glyph's Height = 13, Width = 12, current total allocated size out of MAX(1024) = 860
04-28 00:09:03.919: I/ActivityManager(279): Displayed ucsc.luca.listviewexample/com.example.newsapp.MainActivity: +467ms
04-28 00:09:04.009: W/SignalStrength(356): getLTELevel - rsrp:2147483647 snr:2147483647 rsrpIconLevel:-1 snrIconLevel:-1
04-28 00:09:04.009: W/SignalStrength(356): getLTELevel - rssi:99 rssiIconLevel:0
04-28 00:09:04.009: W/SignalStrength(356): getGsmLevel=2
04-28 00:09:04.009: W/SignalStrength(356): getLevel=2
04-28 00:09:04.309: W/dalvikvm(14018): threadid=1: thread exiting with uncaught exception (group=0x40d06390)
04-28 00:09:04.849: E/Sensors(279): GsSensor: line +83 ~~~handle===0~~en==0~~!n
04-28 00:09:04.859: E/Sensors(279): GsSensor::setDelay: line +114 ~~~handle===0~~ns==200000000~~
04-28 00:09:04.879: I/WindowManager(279): SCREENLAYOUT_SIZE (1:small, 2:normal, 3:large, 4:xlarge) 2
04-28 00:09:04.879: I/fitatc(485): no preference set
04-28 00:09:04.929: E/OpenGLRenderer(485): HUAWEI_DEBUG: glyph's Height = 8, Width = 3, current total allocated size out of MAX(1024) = 0
04-28 00:09:04.929: E/OpenGLRenderer(485): HUAWEI_DEBUG: glyph's Height = 0, Width = 0, current total allocated size out of MAX(1024) = 5
04-28 00:09:04.929: E/OpenGLRenderer(485): HUAWEI_DEBUG: glyph's Height = 7, Width = 6, current total allocated size out of MAX(1024) = 7
04-28 00:09:04.929: E/OpenGLRenderer(485): HUAWEI_DEBUG: glyph's Height = 8, Width = 4, current total allocated size out of MAX(1024) = 15
04-28 00:09:04.929: E/OpenGLRenderer(485): HUAWEI_DEBUG: glyph's Height = 9, Width = 6, current total allocated size out of MAX(1024) = 21
04-28 00:09:06.009: W/SignalStrength(356): getLTELevel - rsrp:2147483647 snr:2147483647 rsrpIconLevel:-1 snrIconLevel:-1
04-28 00:09:06.009: W/SignalStrength(356): getLTELevel - rssi:99 rssiIconLevel:0
04-28 00:09:06.009: W/SignalStrength(356): getGsmLevel=2
04-28 00:09:06.009: W/SignalStrength(356): getLevel=2
04-28 00:09:06.229: W/SignalStrength(457): SignalStrength before validate=SignalStrength: 5 255 -1 -1 -1 -1 -1 99 -32767 -32767 -32767 -32767.0.0 cdma
04-28 00:09:06.229: W/SignalStrength(457): SignalStrength after validate=SignalStrength: 5 255 -120 -160 -120 -1 -1 99 2147483647 2147483647 2147483647 -32767.0.0 cdma
04-28 00:09:06.329: W/lights(279): TP Button Light current value is 60
04-28 00:09:06.329: W/lights(279): button_backlight:property_get,percent =0
04-28 00:09:06.359: W/MemoryDealer(147): madvise(0x42261000, 16384, MADV_REMOVE) returned Operation not supported on transport endpoint
Soluzione
In xml layout you are using "ImageButton" but in your custom "MyAdapter" you are referencing it as "Button". Thats why you might be getting "ClassCastException".
Change Button b = (Button) newView.findViewById(R.id.listButton); to ImageButton b = (ImageButton) newView.findViewById(R.id.listButton);
