我在从位图显示图像时遇到问题 . 我从JsonObject获取base64编码的字符串并解码后获取字节数组和位图 . 我很不走运，所以我现在尝试使用drawable中的相同图像 .
现在问题是我在imageView中设置图像位图时得到空指针异常，并且不知道为什么......
读过这个：ImageView variable returning null even after defined; Android
全班的代码是：`package com.statsports.subjectiveandroid;
public class PlayersListActivity extends Activity {
// URL to make request
private static String URL = "http://000.000.00.0/index.php";
private static int userID;
ArrayList<HashMap<String, Object>> playersList;
ListView playerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.list_view);
Bundle extras = getIntent().getExtras();
userID = extras.getInt("id");
initLayout();
}
private void initLayout() {
playerView = (ListView) findViewById(R.id.list);
playersList = new ArrayList<HashMap<String, Object>>();
playerView.setAdapter(new SimpleAdapter(PlayersListActivity.this,
playersList, R.layout.activity_players_list, null, null));
//playerView.setDividerHeight(0);
}
@Override
protected void onResume() {
if (!ConnectivityStatus.isNetworkAvailable(getApplicationContext())) {
Toast.makeText(PlayersListActivity.this, R.string.network_failed,
Toast.LENGTH_SHORT).show();
} else {
playerView.setAdapter(null);
new PlayersLoadTask().execute();
}
super.onResume();
}
ProgressDialog pDialog;
class PlayersLoadTask extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(PlayersListActivity.this);
pDialog.setMessage("Reading data");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
playersList.clear();
}
@Override
protected String doInBackground(String... arg0) {
try {
ArrayList<BasicNameValuePair> parameters = new ArrayList<BasicNameValuePair>();
parameters.add(new BasicNameValuePair("request", "getPlayers"));
parameters.add(new BasicNameValuePair("clubid", Integer
.toString(userID)));
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(PlayersListActivity.URL);
httpPost.setEntity(new UrlEncodedFormEntity(parameters,
("ISO-8859-1")));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// if this is null the web service returned an empty page
if (httpEntity == null) // response is empty so exit out
return null;
String jsonString = EntityUtils.toString(httpEntity);
// again some simple validation around the returned string
if (jsonString != null && jsonString.length() != 0) // checking
// string
// returned
// from
// service
// to grab
// id
{
JSONArray jsonArray = new JSONArray(jsonString);
for (int i = 0; i < jsonArray.length(); i++) {
HashMap<String, Object> map = new HashMap<String, Object>();
JSONObject jsonObject = (JSONObject) jsonArray.get(i);
int id = jsonObject.getInt("id");
String name = jsonObject.getString("name");
String base64 = jsonObject.getString("image");
map.put("id", id);
map.put("name", name);
if (name == null || name.trim().length() == 0) {
name = "Player unknown";
} else {
map.put("image", (R.drawable.baboon));
}
Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.walcott);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
Bitmap bmp1 = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);
ImageView image = (ImageView) findViewById(R.id.image);
image.setImageBitmap(bmp1);
//ByteArrayOutputStream stream = new ByteArrayOutputStream();
//byte[] decodedString = Base64.decode(
// base64.getBytes("UTF-8"), Base64.NO_PADDING);
/*
* InputStream is = new
* ByteArrayInputStream(decodedString); Bitmap bitmap =
* BitmapFactory.decodeStream(is);
* bitmap.compress(Bitmap.CompressFormat.PNG, 100,
* stream);
*
* if(bitmap != null){ //Drawable drawableImg = new
* BitmapDrawable(getResources(), bitmap); ImageView
* imgView = (ImageView) findViewById(R.id.image);
* imgView.setImageBitmap(bitmap); map.put("image",
* bitmap); }
*/
//String images = new String(decodedString);
//Bitmap decodedByte = BitmapFactory.decodeByteArray(
// decodedString, 0, decodedString.length);
//decodedByte.compress(Bitmap.CompressFormat.PNG, 100,
// stream);
//Log.d("DECODEDBYTE IS: ", decodedByte.toString());
//LayoutInflater inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
//View view = inflater.inflate(R.layout.activity_players_list, null);
//setContentView(view);
//ImageView imgView = (ImageView) findViewById(R.id.image);
//imgView.setImageBitmap(decodedByte);
playersList.add(map);
}
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
Log.e("ERROR SOMEWHERE!!!! ", e.toString());
}
return null;
}
protected void onPostExecute(String file_url) {
if (playersList.size() == 0) {
Toast.makeText(PlayersListActivity.this,
"No players in a list", Toast.LENGTH_SHORT).show();
} else {
playerView.setAdapter(new PlayerListAdapter(
PlayersListActivity.this, playersList,
R.layout.activity_players_list, new String[] { "id",
"image", "name" }, new int[] {
R.id.player_list_id, R.id.image, R.id.name, }));
}
pDialog.dismiss();
}
}
}