BufferInputStream or FileInputStream IOException

Question

I just released an Android app that parses a local file and processes some data. A few days ago, one of my clients informed me of an error, every time he tries to process his file, the application crashes.

This is the error log he sent me:

java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:300)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: lock == null
    at java.io.Reader.<init>(Reader.java:64)
    at java.io.InputStreamReader.<init>(InputStreamReader.java:120)

And the code associated with this is as follows:

// EDIT 1: Following greenapps comment I will put a more realistic version of this 
// method (The first version was invented because I wanted to be breaf)
public void selectFile()
{
    List<File> files = getDocsToParse();
    this.listview.setAdapter(this.myadapter);
    this.listview.setOnItemClickListener(new OnItemClickListener()
    {
        ...
        @Override
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
        parseFile(files.get(position));
                }
        ...
    }
    this.myadapter.addFiles(files);
}

public static List<File> getDocsToParse() {
    File sdcard = Environment.getExternalStorageDirectory();
    File subdir = new File(sdcard, "MyAppFolder/Files/");
    // EDIT 2: I'm using  subdir.mkdirs(); because I want to 
    // create MyAppFolder/Files/ folders the first time the user use the app. 
    // Is this not correct? Should I create these folders any other way? 
    if (!subdir.exists()) {
        subdir.mkdirs();
    }
    File files[] = subdir.listFiles();
    List<File> filterFiles = new ArrayList<File>();
    for (int i = 0; i < files.length; i++) {
        File file = files[i];
        filterFiles.add(file);
    }
    return filterFiles;
}

public void parseFile(File fileToParse)
{
    long totalSize = 0;
    InputStream is = null;
    try {
            totalSize = fileToParse.length();
            is = new BufferedInputStream(new FileInputStream(fileToParse));
    } catch (IOException e) {
        e.printStackTrace();
    }
    BufferedReader reader = null;
    reader = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
    String line = "";
    StringTokenizer st = null;
    try {
        while ((line = reader.readLine()) != null) {
           // Here I parse the file
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

The line that fails is as follows:

reader = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));

I understand that this is because "is" is null, and I will have to catch this case to avoid the application crashing (I will fix this in my next version).

EDIT 3: you are right, greenapps, I will check if the value is null before using it, otherwise I will not use it.

, "is" null, IOException :

 totalSize = fileToParse.length();
    is = new BufferedInputStream(new FileInputStream(fileToParse));

EDIT 4: , IOEXception, , .

, 2 IOException.

, fileToParse , , , "" , files.get(i).getName(), .

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!

5: ctarabusi, parseFile :

public void parseFile(File fileToParse)
{
    long totalSize = 0;
    InputStream is = null;
    try {
            totalSize = fileToParse.length();
            is = new BufferedInputStream(new FileInputStream(fileToParse));
            BufferedReader reader = null;
            reader = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
            String line = "";
            StringTokenizer st = null;
            while ((line = reader.readLine()) != null) {
               // Here I parse the file
            }
    } catch (IOException e) {
          Toast.makeText(getApplicationContext(), "Error parsing file", Toast.LENGTH_LONG).show();
        e.printStackTrace();
    } finally {
        if(is != null)
        {
            try
            {
                is.close();
            }
            catch (IOException e)
            {
                Log.e("", e.getMessage(), e);
            }
        }
    }
}

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Answer 1

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finally, :

InputStream inputStream = null;
try 
{
    ... use your input stream
}
catch (IOException e)
{
    Log.e(TAG, e.getMessage(), e);
}
finally
{
    if (inputStream != null)
    {
        try
        {
            inputStream.close();
        }
        catch (IOException e)
        {
            Log.e(TAG, e.getMessage(), e);
        }
    }
}