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I am developing an application and I have a problem when I try to save a file into the internal storage.

The file is an xml and it's on the res/raw folder on my project. When the application starts, it checks if the file exists or not. If it doesn't exist, it copies the file from the res/raw folder into the internal storage, else it retrieves a field inside the file to check its version and if it's a newer version, it deletes the previous file and copies it again.

Well, the problem is that if I have a new version and I have deleted the previous one, when I'm going to copy it again, it throws an NullPointerExceptcion and I can't find the problem, but I'm using the same code for both situations and I don't know how to solve it.

This is the code I'm using:

 private void writeFileToInternalStorage() { FileOutputStream fos = null; try { InputStream fXmlFile = getResources().openRawResource(R.raw.partidos); File file = getBaseContext().getFileStreamPath("file.xml"); if(file.exists()) { String resourcesVersion= getFileVersion(fXmlFile); String localVersion = getFileVersion(new FileInputStream(file)); if (!resourcesVersion.equalsIgnoreCase(localVersion)) { //file.delete(); fos = openFileOutput("file.xml", Context.MODE_PRIVATE); copyFile(fos, fXmlFile); } } else { fos = openFileOutput("file.xml", Context.MODE_PRIVATE); copyFile(fos, fXmlFile); } } catch(IOException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } finally { if (fos != null) { try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } protected void copyFile(OutputStream fos, InputStream fXmlFile) throws IOException { byte[] buffer = new byte[1024]; int bytesRead = 0; while((bytesRead = fXmlFile.read(buffer)) > 0){ fos.write(buffer, 0, bytesRead); } } protected String getFileVersion(InputStream file) { String version = null; try { DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance(); DocumentBuilder dBuilder = dbFactory.newDocumentBuilder(); Document doc = dBuilder.parse(file); doc.getDocumentElement().normalize(); version = doc.getElementsByTagName("numero").item(0).getFirstChild().getNodeValue(); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return version; }

Any tips for solving it??

PS: The exception is thrown on this statement:

while((bytesRead = fXmlFile.read(buffer)) > 0)

PS2: This is the code from LogCat:

03-03 20:47:07.140: W/System.err(2166): java.lang.NullPointerException: asset 03-03 20:47:07.148: W/System.err(2166): at android.content.res.AssetManager.readAsset(Native Method) 03-03 20:47:07.158: W/System.err(2166): at android.content.res.AssetManager.access$700(AssetManager.java:35) 03-03 20:47:07.168: W/System.err(2166): at android.content.res.AssetManager$AssetInputStream.read(AssetManager.java:573) 03-03 20:47:07.168: W/System.err(2166): at com.jfma75.myapp.MyApp.copyFile(MyApp.java:291) 03-03 20:47:07.178: W/System.err(2166): at com.jfma75.myapp.MyApp.writeFileToInternalStorage(MyApp.java:263) 03-03 20:47:07.178: W/System.err(2166): at com.jfma75.myapp.MyApp.onCreate(MyApp.java:62) 03-03 20:47:07.188: W/System.err(2166): at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:999) 03-03 20:47:07.188: W/System.err(2166): at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4151) 03-03 20:47:07.198: W/System.err(2166): at android.app.ActivityThread.access$1300(ActivityThread.java:130) 03-03 20:47:07.198: W/System.err(2166): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1255) 03-03 20:47:07.208: W/System.err(2166): at android.os.Handler.dispatchMessage(Handler.java:99) 03-03 20:47:07.208: W/System.err(2166): at android.os.Looper.loop(Looper.java:137) 03-03 20:47:07.218: W/System.err(2166): at android.app.ActivityThread.main(ActivityThread.java:4745) 03-03 20:47:07.218: W/System.err(2166): at java.lang.reflect.Method.invokeNative(Native Method) 03-03 20:47:07.228: W/System.err(2166): at java.lang.reflect.Method.invoke(Method.java:511) 03-03 20:47:07.237: W/System.err(2166): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 03-03 20:47:07.237: W/System.err(2166): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-03 20:47:07.248: W/System.err(2166): at dalvik.system.NativeStart.main(Native Method)
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  • Try removing file.delete(), it will just overwrite the file Commented Mar 3, 2013 at 19:30
  • Paste Logcat in the question. Commented Mar 3, 2013 at 19:34
  • @Matt, I tried that, but I still have the same issue. Commented Mar 3, 2013 at 19:51
  • Add the code for copyFile to your question. Also, why do you do your initial version check with new File(dir, "file.xml"); but then just use a relative file name (openFileOutput("file.xml", Context.MODE_PRIVATE)) for the copy function? Commented Mar 3, 2013 at 19:51
  • 1
    I think I know what the problem is. You open the resource file and hold it in an InputStream then you call String resourcesVersion= getFileVersion(fXmlFile); which, I guess, is your own private function to get the version. I'm betting you advance the InputStream or close it in that function. Then, when you later call copyFile the InputStream is either consumed or closed. Try just removing that line and put a constant String resourcesVersion = "versionThatDoesn'tMatch" just to test the InputStream Commented Mar 3, 2013 at 21:16

2 Answers 2

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Just added my comment as the answer since it seemed to fix the OP's issue and will close this question:

I think I know what the problem is. You open the resource file and hold it in an InputStream then you call String resourcesVersion= getFileVersion(fXmlFile); which, I guess, is your own private function to get the version. I'm betting you advance the InputStream or close it in that function. Then, when you later call copyFile the InputStream is either consumed or closed. Try just removing that line and put a constant String resourcesVersion = "versionThatDoesn'tMatch"; just to test the InputStream

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It appears that in the statement 

InputStream fXmlFile = getResources().openRawResource(R.raw.partidos);

the variable fXmlFile is null. You can check why that happens.

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