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POListView throws NULL Pointer exception
 

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  1. POListView throws NULL Pointer exception
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    <p>read a lot of the questions about NPE's.. still in the dark.</p> <p>I declare a listview :</p> <pre><code>public class SelecteerKernen extends Activity { protected WoordData kerndata; public ListView listView = null; </code></pre> <p>Later, I fill it with data from a SQLite dBase. This works.</p> <pre><code>// Fill Listview with the kern-names ListView listView = (ListView) findViewById(R.id.kernenlist); listView.setAdapter(new ArrayAdapter&lt;String&gt;(this,android.R.layout.simple_list_item_multiple_choice, al)); </code></pre> <p>But then, when I want to count the items, to save the checked items to preferences, I get a NPE on the int count = ... line of this code .</p> <p>Edit I solved the count.. line, now the if (this.listView)... line throws the NPE.. Argh! :</p> <pre><code> private String getSavedItems() { String savedItems = ""; int count = this.listView.getAdapter().getCount(); for (int i = 0; i &lt; count; i++) { //edit now THIS line trows the NPE : if (this.listView.isItemChecked(i)) { if (savedItems.length() &gt; 0) { savedItems += "," + this.listView.getItemAtPosition(i); } else { savedItems += this.listView.getItemAtPosition(i); } } } return savedItems; </code></pre> <p>Thanks for the help!!</p> <hr> <p>PS. I noticed that users are asked for LogCats. How can that help to find the error? Here's mine :</p> <blockquote> <p>11-01 19:42:35.680: W/dalvikvm(28146): threadid=1: thread exiting with uncaught exception (group=0x40015560) 11-01 19:42:35.700: E/AndroidRuntime(28146): FATAL EXCEPTION: main 11-01 19:42:35.700: E/AndroidRuntime(28146): java.lang.NullPointerException 11-01 19:42:35.700: E/AndroidRuntime(28146): at happyworx.nl.Flitswoorden.SelecteerKernen.getSavedItems(SelecteerKernen.java:163) 11-01 19:42:35.700: E/AndroidRuntime(28146): at happyworx.nl.Flitswoorden.SelecteerKernen.SavePreferences(SelecteerKernen.java:121) 11-01 19:42:35.700: E/AndroidRuntime(28146): at happyworx.nl.Flitswoorden.SelecteerKernen.access$0(SelecteerKernen.java:115) 11-01 19:42:35.700: E/AndroidRuntime(28146): at happyworx.nl.Flitswoorden.SelecteerKernen$1.onClick(SelecteerKernen.java:72) ...</p> </blockquote>
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    1. USKees Koenen
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    1. COI solved this by adding `public ListAdapter la = null;` and defining the adapter like this : `la = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice, al); listView.setAdapter(la);`.. But now, I'm getting the same error on the line `if (this.listView.isItemChecked(i)) {`.. guess that's what happens if you Google a lot and solve errors without actually knowing what the cause is ;) :-S.
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      1. USKees Koenen
    2. COOh.. and I changed the count from `listview.getadapter().count()` to `int count = la.getCount();`.. So I'm actually not solving the problem, but counting the arrayitems instead of the listview items. And thusly moving the problem to the next line that relies on the listview() thingie.
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      1. POListView throws NULL Pointer exception
      1. USKees Koenen
    3. COPondering.. is it because the class extends Activity instead of ListActivity? But.. if I change that, I get into the part where I have to change /@id+ to android:id in the XML, and add android.R to imports.. I've tried that.. it was HORROR..
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      1. POListView throws NULL Pointer exception
      1. USKees Koenen
 

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