Я пытаюсь создать приложение для чтения RSS для Android, но продолжаю получать исключение нулевого указателя. Я новичок в java и не могу сказать, не возвращает ли URL-адрес фида какие-либо данные или данные не хранятся должным образом.
мой логарифм читает:
08-08 18:44:25.840: E/Trace(621): error opening trace file: No such file or directory (2)
08-08 18:44:25.910: W/ActivityThread(621): Application com.app.fullmetalmanga is waiting for the debugger on port 8100...
08-08 18:44:25.930: I/System.out(621): Sending WAIT chunk
08-08 18:44:25.951: I/dalvikvm(621): Debugger is active08-08 18:44:26.140: I/System.out(621): Debugger has connected
08-08 18:44:27.710: I/System.out(621): debugger has settled (1382)
08-08 18:44:29.291: D/gralloc_goldfish(621): Emulator without GPU emulation detected.
08-08 18:44:48.060: W/System.err(621): java.lang.NullPointerException
08-08 18:44:48.760: W/System.err(621): at java.util.Calendar.setTime(Calendar.java:1324)
08-08 18:44:48.810: W/System.err(621): at java.text.SimpleDateFormat.formatImpl(SimpleDateFormat.java:536)
08-08 18:44:49.050: W/System.err(621): at java.text.SimpleDateFormat.format(SimpleDateFormat.java:821)
08-08 18:44:49.150: W/System.err(621): at java.text.DateFormat.format(DateFormat.java:376)
08-08 18:44:49.490: W/System.err(621): at com.app.fullmetalmanga.RssItem.getDate(RssItem.java:48)
08-08 18:44:49.810: W/System.err(621): at com.app.fullmetalmanga.MainActivity$RSSHandler.endElement(MainActivity.java:146)
08-08 18:44:50.090: W/System.err(621): at org.apache.harmony.xml.ExpatParser.endElement(ExpatParser.java:156)
08-08 18:44:50.250: W/System.err(621): at org.apache.harmony.xml.ExpatParser.appendBytes(Native Method)
08-08 18:44:50.410: W/System.err(621): at org.apache.harmony.xml.ExpatParser.parseFragment(ExpatParser.java:513)
08-08 18:44:50.610: W/System.err(621): at org.apache.harmony.xml.ExpatParser.parseDocument(ExpatParser.java:474)
08-08 18:44:50.791: W/System.err(621): at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:321)
08-08 18:44:50.990: W/System.err(621): at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:279)
08-08 18:44:51.800: W/System.err(621): at com.app.fullmetalmanga.MainActivity$SAXHelper.parseContent(MainActivity.java:112)
08-08 18:44:51.870: W/System.err(621): at com.app.fullmetalmanga.MainActivity$loadingTask.doInBackground(MainActivity.java:74)
08-08 18:44:52.350: W/System.err(621): at com.app.fullmetalmanga.MainActivity$loadingTask.doInBackground(MainActivity.java:1)
08-08 18:44:52.700: W/System.err(621): at android.os.AsyncTask$2.call(AsyncTask.java:287)
08-08 18:44:53.070: W/System.err(621): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
08-08 18:44:53.190: W/System.err(621): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
08-08 18:44:53.370: W/System.err(621): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
08-08 18:44:53.561: W/System.err(621): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
08-08 18:44:53.980: W/System.err(621): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
08-08 18:44:54.051: W/System.err(621): at java.lang.Thread.run(Thread.java:856)
И моя основная деятельность:
public class MainActivity extends Activity {
/** Called when the activity is first created. */
ListView lv1;
ProgressDialog ShowProgress;
public ArrayList<RssItem> RssItemList = new ArrayList<RssItem>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
lv1 = (ListView) findViewById(R.id.listView1);
ShowProgress = ProgressDialog.show(MainActivity.this, "",
"Loading. Please wait...", true);
new loadingTask().execute("http://fandom.com/rss/news/manga");
lv1.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Intent intent = new Intent(Intent.ACTION_VIEW).setData(Uri
.parse(RssItemList.get(position).getTitle()));
startActivity(intent);
}
});
}
class loadingTask extends AsyncTask<String, Void, String> {
protected String doInBackground(String... urls) {
SAXHelper sh = null;
try {
sh = new SAXHelper(urls[0]);
} catch (MalformedURLException e) {
e.printStackTrace();
}
sh.parseContent("");
return "";
}
protected void onPostExecute(String s) {
lv1.setAdapter(new EfficientAdapter(MainActivity.this, RssItemList));
ShowProgress.dismiss();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
class SAXHelper {
public HashMap<String, String> userList = new HashMap<String, String>();
private URL url2;
public SAXHelper(String url1) throws MalformedURLException {
this.url2 = new URL(url1);
}
public RSSHandler parseContent(String parseContent) {
RSSHandler df = new RSSHandler();
try {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
xr.setContentHandler(df);
xr.parse(new InputSource(url2.openStream()));
} catch (Exception e) {
e.printStackTrace();
}
return df;
}
}
class RSSHandler extends DefaultHandler {
private RssItem currentPost = new RssItem();
StringBuffer chars = new StringBuffer();
@Override
public void startElement(String uri, String localName, String qName,
Attributes atts) {
chars = new StringBuffer();
if (localName.equalsIgnoreCase("item")) {
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (localName.equalsIgnoreCase("title")
&& currentPost.getTitle() == null) {
currentPost.setTitle(chars.toString());
}
if (localName.equalsIgnoreCase("pubDate")
&& currentPost.getDate() == null) {
currentPost.setDate(chars.toString());
}
/*if (localName.equalsIgnoreCase("thumbnail")
&& currentPost.getThumbnail() == null) {
currentPost.setThumbnail(chars.toString());
} */
if (localName.equalsIgnoreCase("link")
&& currentPost.getLink() == null) {
currentPost.setLink(chars.toString());
}
if (localName.equalsIgnoreCase("item")) {
RssItemList.add(currentPost);
currentPost = new RssItem();
}
}
@Override
public void characters(char ch[], int start, int length) {
chars.append(new String(ch, start, length));
}
}
}
Мой класс RssItem:
public class RssItem {
static SimpleDateFormat FORMATTER =
new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z");
private String title;
private URL link;
private String description;
private Date date;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title.trim();
}
// getters and setters omitted for brevity
public URL getLink() {
return link;
}
public void setLink(String link) {
try {
this.link = new URL(link);
} catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description.trim();
}
public String getDate() {
return FORMATTER.format(this.date);
}
public void setDate(String date) {
// pad the date if necessary
while (!date.endsWith("00")){
date += "0";
}
try {
this.date = FORMATTER.parse(date.trim());
} catch (ParseException e) {
throw new RuntimeException(e);
}
}
}
Мой код был создан с использованием этого пример. Изменение только URL-адреса и использование моего собственного модифицированного файла «Post». (переименован в RssItem)
