我正在尝试从http://projectxapp.herokuapp.com/dashboard/ads/api/v1/ads/的 Json 格式获取数据
它显示 NullPointerException，我尝试了多种方法来解决它。但是我还是没有想法！！objectList 似乎是空的。
public class ImagePagerActivity extends Activity {
// url to make request
private static String url =
"http://projectxapp.herokuapp.com/dashboard/ads/api/v1/ads/";
// JSON Node names
static final String TAG_META = "meta";
static final String TAG_META_LIMIT = "limit";
private static final String TAG_META_NEXT = "next";
private static final String TAG_META_total_count = "count";
private static final String TAG_OBJECTS = "objects";
private static final String TAG_OBJECTS_END_TIME = "endTime";
private static final String TAG_OBJECTS_ID = "id";
private static final String TAG_OBJECTS_LINK = "link";
private static final String TAG_OBJECTS_PHOTO = "photo";
private static final String TAG_OBJECTS_PHOTO_HEIGHT = "height";
static final String TAG_OBJECTS_PHOTO_RESOURCE_URI = "resourceUri";
private static final String TAG_OBJECTS_PHOTO_SOURCE = "source";
private static final String TAG_OBJECTS_PHOTO_WIDTH = "width";
private static final String TAG_OBJECTS_RESOURCE_URI = "OResourceUri";
private static final String TAG_OBJECTS_START_TIME = "startTime";
// contacts JSONArray
JSONArray meta = null;
JSONArray objects = null;
//
private static final String TEST_FILE_NAME = "Universal Image Loader @#&=+-_.,!()~'%20.png";
private static final String STATE_POSITION = "STATE_POSITION";
ImageLoader imageLoader = ImageLoader.getInstance();
DisplayImageOptions options;
ViewPager pager;
@SuppressWarnings("null")
@SuppressLint("NewApi")
public void onCreate(Bundle savedInstanceState) {
//
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork()
.penaltyLog().build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
.detectLeakedSqlLiteObjects().detectLeakedClosableObjects()
.penaltyLog().penaltyDeath().build());
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
;
setContentView(R.layout.mos);
File testImageOnSdCard = new File("/mnt/sdcard", TEST_FILE_NAME);
if (!testImageOnSdCard.exists()) {
copyTestImageToSdCard(testImageOnSdCard);
}
ArrayList<HashMap<String, String>> objectsList = new
ArrayList<HashMap<String, String>>();
JSONParser jParser = new JSONParser();
JSONObject json = null;
try {
json = jParser.getStringContent(url);
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
// Getting Array of Contacts
objects = json.getJSONArray(TAG_OBJECTS);
// looping through All Contacts
for (int i = 0; i < objects.length(); i++) {
JSONObject c = objects.getJSONObject(i);
String link = c.getString(TAG_OBJECTS_LINK);
JSONObject photo = c.getJSONObject(TAG_OBJECTS_PHOTO);
String source = photo.getString(TAG_OBJECTS_PHOTO_SOURCE);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_OBJECTS_LINK, link);
map.put(TAG_OBJECTS_PHOTO_SOURCE, source);
// adding HashList to ArrayList
objectsList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
String[] imageUrls = null;
if(objectsList.isEmpty());
Toast.makeText(this, "No Data", Toast.LENGTH_LONG).show();
Log.i("getData1", "!!!!!!!!!!!");
//
for(int i=0; i<objects.length(); i++)
{
Log.i("getData2", "!!!!!!!!!!!");
imageUrls[i]=objectsList.get(i).get(TAG_OBJECTS_PHOTO_RESOURCE_URI);
Log.i("getData3", "!!!!!!!!!!!");
}
//
private void copyTestImageToSdCard(final File testImageOnSdCard) {
new Thread(new Runnable() {
@Override
public void run() {
try {
InputStream is = getAssets().open(TEST_FILE_NAME);
FileOutputStream fos = new FileOutputStream(
testImageOnSdCard);
byte[] buffer = new byte[8192];
int read;
try {
while ((read = is.read(buffer)) != -1) {
fos.write(buffer, 0, read);
}
} finally {
fos.flush();
fos.close();
is.close();
}
} catch (IOException e) {
L.w("Can't copy test image onto SD card");
}
}
}).start();
}
有 JSONParser()。
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public static JSONObject getStringContent(String uri) throws Exception {
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(uri));
HttpResponse response = client.execute(request);
InputStream ips = response.getEntity().getContent();
BufferedReader buf = new BufferedReader(new InputStreamReader(ips,"UTF-8"));
StringBuilder sb = new StringBuilder();
String s;
while(true )
{
s = buf.readLine();
if(s==null || s.length()==0)
break;
sb.append(s);
}
buf.close();
ips.close();
jObj = new JSONObject(sb.toString());
return jObj;
}
}
这些是下面的 logcat 消息！
04-05 07:25:17.889: E/StrictMode(630): at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
04-05 07:25:17.889: E/StrictMode(630): at java.lang.Thread.run(Thread.java:856)
04-05 07:25:21.831: E/AndroidRuntime(3285): FATAL EXCEPTION: main
04-05 07:25:21.831: E/AndroidRuntime(3285): java.lang.RuntimeException: Unable to
start activity ComponentInfo{com.sai.mosorder/com.sai.mosorder.ImagePagerActivity}:
java.lang.NullPointerException
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread.access$600(ActivityThread.java:141)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.os.Handler.dispatchMessage(Handler.java:99)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.os.Looper.loop(Looper.java:137)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread.main(ActivityThread.java:5041)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
java.lang.reflect.Method.invokeNative(Native Method)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
java.lang.reflect.Method.invoke(Method.java:511)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
dalvik.system.NativeStart.main(Native Method)
04-05 07:25:21.831: E/AndroidRuntime(3285): Caused by:
java.lang.NullPointerException
04-05 07:25:21.831: E/AndroidRuntime(3285): at
com.sai.mosorder.ImagePagerActivity.onCreate(ImagePagerActivity.java:132)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.Activity.performCreate(Activity.java:5104)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
04-05 07:25:21.831: E/AndroidRuntime(3285): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
04-05 07:25:21.831: E/AndroidRuntime(3285): ... 11 more
04-05 07:25:22.200: E/SurfaceFlinger(37): ro.sf.lcd_density must be defined as a
build property
04-05 07:25:22.560: E/SurfaceFlinger(37): ro.sf.lcd_density must be defined as a
build property
04-05 07:26:07.869: E/ActivityThread(630): at
com.android.exchange.ExchangeService$7.run(ExchangeService.java:1856)