title: Erro reading an epub file in Android
body: <p>I want to read epub file page by page in my Android app.</p>
  
  <p>I have tried but am getting a nullPointer Exception for at this line:</p>
  
  <pre><code>Bitmap coverImage = BitmapFactory.decodeStream(book.getCoverImage().getInputStream());
  </code></pre>
  
  <p>Can anyone explain why I am getting this error or how to do read books page by page?</p>
  
  <p>Here is my Activity code:</p>
  
  <pre><code>public class LogTestBookInfo extends Activity
   {
     @Override
     public void onCreate(Bundle savedInstanceState) {
  
      super.onCreate(savedInstanceState);
  
      setContentView(R.layout.main);
  
      AssetManager assetManager = getAssets();
  
      try {
  
        // find InputStream for book
        InputStream epubInputStream = assetManager.open("assets/books/wodehouse.epub");
  
          // Load Book from inputStream
        Book book = (new EpubReader()).readEpub(epubInputStream);
  
  
        // Log the book's authors
  
        Log.i("epublib", "author(s): " + book.getMetadata().getAuthors());
  
        // Log the book's title
        Log.i("epublib", "title: " + book.getTitle());
  
        // Log the book's coverimage property
        Bitmap coverImage = BitmapFactory.decodeStream(book.getCoverImage().getInputStream());
  
        Log.i("epublib", "Coverimage is " + coverImage.getWidth() + " by "+ coverImage.getHeight() + " pixels");
        // Log the tale of contents
        logTableOfContents(book.getTableOfContents().getTocReferences(), 0);
  
      }
      catch (IOException e) 
      {
  
        Log.e("epublib", e.getMessage());
  
      }
  
    }
  
  
    private void logTableOfContents(List&lt;TOCReference&gt; tocReferences, int depth) {
  
      if (tocReferences == null) {
  
        return;
  
      }
  
      for (TOCReference tocReference : tocReferences) {
  
        StringBuilder tocString = new StringBuilder();
  
        for (int i = 0; i &lt; depth; i++) {
  
          tocString.append("\t");
  
        }
  
        tocString.append(tocReference.getTitle());
  
        Log.i("epublib", tocString.toString());
  
  
        logTableOfContents(tocReference.getChildren(), depth + 1);
  
      }
  
    }
  
  }
  </code></pre>
  
  <p>Here is my logcat information:</p>
  
  <pre><code>12-04 11:12:08.606: I/AndroidLoggerFactory(334): Logger name 'nl.siegmann.epublib.epub.EpubReader' exceeds maximum length of 23 characters, using 'n*.s*.e*.e*.EpubReader' instead.
  12-04 11:12:08.635: I/AndroidLoggerFactory(334): Logger name 'nl.siegmann.epublib.domain.Resource' exceeds maximum length of 23 characters, using 'n*.s*.e*.d*.Resource' instead.
  12-04 11:12:08.886: I/AndroidLoggerFactory(334): Logger name 'nl.siegmann.epublib.epub.EpubProcessorSupport' exceeds maximum length of 23 characters, using 'n*.s*.e*.e*.EpubProces*' instead.
  12-04 11:12:08.996: I/AndroidLoggerFactory(334): Logger name 'nl.siegmann.epublib.epub.PackageDocumentReader' exceeds maximum length of 23 characters, using 'n*.s*.e*.e*.PackageDoc*' instead.
  12-04 11:12:09.336: I/AndroidLoggerFactory(334): Logger name 'nl.siegmann.epublib.epub.NCXDocument' exceeds maximum length of 23 characters, using 'n*.s*.e*.e*.NCXDocument' instead.
  12-04 11:12:09.565: I/epublib(334): author(s): [B., Gummere, Francis]
  12-04 11:12:09.565: I/epublib(334): title: Beowulf
  12-04 11:12:09.606: E/AndroidRuntime(334): FATAL EXCEPTION: main
  12-04 11:12:09.606: E/AndroidRuntime(334): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bookapp/com.bookapp.LogTestBookInfo}: java.lang.NullPointerException
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.os.Handler.dispatchMessage(Handler.java:99)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.os.Looper.loop(Looper.java:123)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread.main(ActivityThread.java:3683)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at java.lang.reflect.Method.invokeNative(Native Method)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at java.lang.reflect.Method.invoke(Method.java:507)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at dalvik.system.NativeStart.main(Native Method)
  12-04 11:12:09.606: E/AndroidRuntime(334): Caused by: java.lang.NullPointerException
  12-04 11:12:09.606: E/AndroidRuntime(334):  at com.bookapp.LogTestBookInfo.onCreate(LogTestBookInfo.java:80)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
  12-04 11:12:09.606: E/AndroidRuntime(334):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
  12-04 11:12:09.606: E/AndroidRuntime(334):  ... 11 more
  </code></pre>