Java adds a content sample share to the end of the file

BufferedWriter out = null;   
try {   
    out = new BufferedWriter(new FileWriter( " filename " , true));   
    out.write("aString");   
} catch (IOException e) {   
    // error processing code   
} finally {   
    if (out != null) {   
        out.close();   
    }   
}