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POjava.lang.NullPointerException in AsyncTask
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  1. POjava.lang.NullPointerException in AsyncTask
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    copied!<p>I'm trying to "optimize" my app's code using AsycTask, but I receive the java.lang.NullPointerException error. </p> <p>Can you please help me to figure it out where I'm doing it wrong?</p> <pre><code>package it.vscreazioni.farmachimica; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.List; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; import android.app.ProgressDialog; import android.os.AsyncTask; import android.os.Bundle; import android.widget.ListView; import com.actionbarsherlock.app.SherlockActivity; import com.actionbarsherlock.view.Menu; public class MostraTutti extends SherlockActivity { final ListView lv = (ListView) findViewById(R.id.listView); final List&lt;ListViewItem&gt; items = new ArrayList&lt;MostraTutti.ListViewItem&gt;(); final ArrayList&lt;String&gt; nome = new ArrayList&lt;String&gt;(); final ArrayList&lt;String&gt; immagine = new ArrayList&lt;String&gt;(); ... ... final int array_image2[] ={R.drawable.iodocloroidrossichinolina,R.drawable.acidoacetilsalicilico, R.drawable.acidoascorbico,R.drawable.acidobarbiturico,R.drawable.acidobenzoico,...}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.mostra_tutti); getSupportActionBar().setDisplayShowHomeEnabled(false); RssFeedTask rssTask = new RssFeedTask(); rssTask.execute(); } private class RssFeedTask extends AsyncTask&lt;String, Void, String&gt; { private ProgressDialog Dialog; String response = ""; @Override protected void onPreExecute() { Dialog = new ProgressDialog(MostraTutti.this); Dialog.setMessage("Leggo..."); Dialog.show(); } @Override protected String doInBackground(String... urls) { InputStream xmlFile = getResources().openRawResource(R.raw.sostanze); try { DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance(); DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder(); final Document document = documentBuilder.parse(xmlFile); document.getDocumentElement().normalize(); NodeList nodeList = document.getElementsByTagName("sostanza"); for (int i = 0; i &lt; nodeList.getLength(); i++) { final int indice = i; nome.add(document.getElementsByTagName("nome").item(indice).getTextContent()); iupac.add(document.getElementsByTagName("iupac").item(indice).getTextContent()); aspetto.add(document.getElementsByTagName("aspetto").item(indice).getTextContent()); formula.add(document.getElementsByTagName("formula").item(indice).getTextContent()); immagine.add(document.getElementsByTagName("immagine").item(indice).getTextContent()); appartenenza.add(document.getElementsByTagName("appartenenza").item(indice).getTextContent()); spiegazione.add(document.getElementsByTagName("spiegazione").item(indice).getTextContent()); tempFus.add(document.getElementsByTagName("temperaturaFusione").item(indice).getTextContent()); tempEboll.add(document.getElementsByTagName("temperaturaEbollizione").item(indice).getTextContent()); solubilita.add(document.getElementsByTagName("solubilita").item(indice).getTextContent()); note.add(document.getElementsByTagName("eccezioni").item(indice).getTextContent()); String str = document.getElementsByTagName("formula").item(indice).getTextContent(); str = str.replaceAll("0", "\u2080"); str = str.replaceAll("1", "\u2081"); str = str.replaceAll("2", "\u2082"); str = str.replaceAll("3", "\u2083"); str = str.replaceAll("4", "\u2084"); str = str.replaceAll("5", "\u2085"); str = str.replaceAll("6", "\u2086"); str = str.replaceAll("7", "\u2087"); str = str.replaceAll("8", "\u2088"); str = str.replaceAll("9", "\u2089"); final String stringa = str; formulaConvertita.add(stringa); items.add(new ListViewItem() {{ ThumbnailResource = array_image2[indice]; Title = document.getElementsByTagName("nome").item(indice).getTextContent(); SubTitle = stringa; }}); }; } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } catch (ParserConfigurationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } return response; } @Override protected void onPostExecute(String result) { CustomListViewAdapter adapter = new CustomListViewAdapter(MostraTutti.this,items); lv.setAdapter(adapter); /* _adapter = new CustomListViewAdapter(News.this,Rssparser.items); lv=(ListView)findViewById(R.id.list); lv.setAdapter(_adapter); Dialog.dismiss(); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView&lt;?&gt; arg0, View v, int position, long id) { Context context = getBaseContext(); Intent myIntent = new Intent(context, LeggiArticolo.class); myIntent.putExtra("testo",Rssparser.testo.get(position)); myIntent.putExtra("titolo",Rssparser.titolo.get(position)); myIntent.putExtra("immagine",Rssparser.immagini.get(position)); myIntent.putExtra("link",Rssparser.indirizzo.get(position)); startActivityForResult(myIntent, 0); } } ); */ } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getSupportMenuInflater().inflate(R.menu.activity_main, menu); return true; } class ListViewItem { public int ThumbnailResource; public String Title; public String SubTitle; } } </code></pre> <p>And I get this Error:</p> <pre><code>04-25 11:43:57.872: W/dalvikvm(1663): threadid=1: thread exiting with uncaught exception (group=0x40a13300) 04-25 11:43:57.902: E/AndroidRuntime(1663): FATAL EXCEPTION: main 04-25 11:43:57.902: E/AndroidRuntime(1663): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{it.vscreazioni.farmachimica/it.vscreazioni.farmachimica.MostraTutti}: java.lang.NullPointerException 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread.access$600(ActivityThread.java:130) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.os.Handler.dispatchMessage(Handler.java:99) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.os.Looper.loop(Looper.java:137) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread.main(ActivityThread.java:4745) 04-25 11:43:57.902: E/AndroidRuntime(1663): at java.lang.reflect.Method.invokeNative(Native Method) 04-25 11:43:57.902: E/AndroidRuntime(1663): at java.lang.reflect.Method.invoke(Method.java:511) 04-25 11:43:57.902: E/AndroidRuntime(1663): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 04-25 11:43:57.902: E/AndroidRuntime(1663): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 04-25 11:43:57.902: E/AndroidRuntime(1663): at dalvik.system.NativeStart.main(Native Method) 04-25 11:43:57.902: E/AndroidRuntime(1663): Caused by: java.lang.NullPointerException 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.Activity.findViewById(Activity.java:1825) 04-25 11:43:57.902: E/AndroidRuntime(1663): at it.vscreazioni.farmachimica.MostraTutti.&lt;init&gt;(MostraTutti.java:25) 04-25 11:43:57.902: E/AndroidRuntime(1663): at java.lang.Class.newInstanceImpl(Native Method) 04-25 11:43:57.902: E/AndroidRuntime(1663): at java.lang.Class.newInstance(Class.java:1319) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.Instrumentation.newActivity(Instrumentation.java:1053) 04-25 11:43:57.902: E/AndroidRuntime(1663): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974) 04-25 11:43:57.902: E/AndroidRuntime(1663): ... 11 more </code></pre> <p>Can you please help me?</p> <p>EDIT AFTER ANSWER:</p> <pre><code>public class MostraTutti extends SherlockActivity { ListView lv; final List&lt;ListViewItem&gt; items = new ArrayList&lt;MostraTutti.ListViewItem&gt;(); final ArrayList&lt;String&gt; nome = new ArrayList&lt;String&gt;(); ... final int array_image2[] ={R.drawable.iodocloroidrossichinolina,R.drawable.acidoacetilsalicilico, R.drawable.acidoascorbico,R.drawable.acidobarbiturico,R.drawable.acidobenzoico, ... }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.mostra_tutti); lv = (ListView) findViewById(R.id.listView); getSupportActionBar().setDisplayShowHomeEnabled(false); RssFeedTask rssTask = new RssFeedTask(); rssTask.execute(); } private class RssFeedTask extends AsyncTask&lt;String, Void, String&gt; { private ProgressDialog Dialog; String response = ""; @Override protected void onPreExecute() { Dialog = new ProgressDialog(MostraTutti.this); Dialog.setMessage("Leggo le sostanze..."); Dialog.show(); } @Override protected String doInBackground(String... urls) { InputStream xmlFile = getResources().openRawResource(R.raw.sostanze); try { DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance(); DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder(); final Document document = documentBuilder.parse(xmlFile); document.getDocumentElement().normalize(); //tagHandler.handleChannelTag(document); NodeList nodeList = document.getElementsByTagName("sostanza"); for (int i = 0; i &lt; nodeList.getLength(); i++) { final int indice = i; nome.add(document.getElementsByTagName("nome").item(indice).getTextContent()); iupac.add(document.getElementsByTagName("iupac").item(indice).getTextContent()); aspetto.add(document.getElementsByTagName("aspetto").item(indice).getTextContent()); formula.add(document.getElementsByTagName("formula").item(indice).getTextContent()); immagine.add(document.getElementsByTagName("immagine").item(indice).getTextContent()); appartenenza.add(document.getElementsByTagName("appartenenza").item(indice).getTextContent()); spiegazione.add(document.getElementsByTagName("spiegazione").item(indice).getTextContent()); tempFus.add(document.getElementsByTagName("temperaturaFusione").item(indice).getTextContent()); tempEboll.add(document.getElementsByTagName("temperaturaEbollizione").item(indice).getTextContent()); solubilita.add(document.getElementsByTagName("solubilita").item(indice).getTextContent()); note.add(document.getElementsByTagName("eccezioni").item(indice).getTextContent()); String str = document.getElementsByTagName("formula").item(indice).getTextContent(); str = str.replaceAll("0", "\u2080"); str = str.replaceAll("1", "\u2081"); str = str.replaceAll("2", "\u2082"); str = str.replaceAll("3", "\u2083"); str = str.replaceAll("4", "\u2084"); str = str.replaceAll("5", "\u2085"); str = str.replaceAll("6", "\u2086"); str = str.replaceAll("7", "\u2087"); str = str.replaceAll("8", "\u2088"); str = str.replaceAll("9", "\u2089"); final String stringa = str; formulaConvertita.add(stringa); items.add(new ListViewItem() {{ ThumbnailResource = array_image2[indice]; Title = document.getElementsByTagName("nome").item(indice).getTextContent(); SubTitle = stringa; }}); }; } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } catch (ParserConfigurationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } return response; } @Override protected void onPostExecute(String result) { Dialog.dismiss(); CustomListViewAdapter adapter = new CustomListViewAdapter(MostraTutti.this,items); lv.setAdapter(adapter); lv.setOnItemClickListener( new OnItemClickListener() { public void onItemClick(AdapterView&lt;?&gt; arg0, View v, int position, long id) { Context context = getBaseContext(); Intent myIntent = new Intent(context, Dettagli.class); myIntent.putExtra("nome_sostanza",nome.get(position)); // myIntent.putExtra("formula",formula.get(position)); myIntent.putExtra("iupac",iupac.get(position)); myIntent.putExtra("aspetto",aspetto.get(position)); myIntent.putExtra("appartenenza",appartenenza.get(position)); myIntent.putExtra("solubilita",solubilita.get(position)); myIntent.putExtra("tempFus",tempFus.get(position)); myIntent.putExtra("tempEboll",tempEboll.get(position)); myIntent.putExtra("spiegazione",spiegazione.get(position)); myIntent.putExtra("immagine", array_image2[position]); myIntent.putExtra("formulaConvertita", formulaConvertita.get(position)); myIntent.putExtra("note", note.get(position)); startActivityForResult(myIntent, 0); } } ); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getSupportMenuInflater().inflate(R.menu.activity_main, menu); return true; } class ListViewItem { public int ThumbnailResource; public String Title; public String SubTitle; } } </code></pre> <p>And the error's gone! But there's a strange behaviour: now in simulator it take's longer than the "normal" way:</p> <p>16 seconds with the not Async and 1 minute with Async...</p>
 

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