Develop Reference

Why won't my lambda write to the .txt files it creates?

I have an AWS lambda program written in Java that is supposed to create a bunch of txt files then write URLs to them and move them to a bucket. It appears to be creating the .txt files in the /tmp/ folder of the lambda but not writing anything to them, because I keep getting FL2: null. The bucket gets .txt files with the right names but they're empty.
The FileNames are all of the format "/tmp/[name].txt". The map has txt filenames followed by a list of URLs. The buffered reader was simply my own code to see if it could read the .txts that were created.
for (Map.Entry<String, ArrayList<String>> entry: files.entrySet()) {
String fileName = entry.getKey();
ArrayList<String> list = entry.getValue();
File file = new File(fileName);
FileWriter writer = null;
BufferedWriter bw = null;
BufferedReader br = null;
try {
if (!file.exists()){
log.info("It doesn't exist as a temp.");
if( !file.createNewFile()){
log.error(fileName+" not created. Skipping");
continue;
}
}
writer = new FileWriter(file, StandardCharsets.UTF_8);
bw = new BufferedWriter(writer);
for (int i=0; i< list.size(); i++) {
String url = list.get(i);
log.info("Inserting " + url + " into file " + fileName);
if (i !=0){
bw.write("\n");
}
bw.write(url);
}
br = new BufferedReader(new FileReader(file, StandardCharsets.UTF_8));
log.info("FL2: "+br.readLine());
String key = fileName.substring(5);
amazonS3.putObject("[bucketname]", key, file);
} catch (Exception e) {
e.printStackTrace();
}
finally{
try {
if (writer != null) {
writer.close();
}
if (bw != null) {
bw.close();
}
if (br != null) {
br.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
log.info("End of the sitemap generator");
}
I tried the above code, and I tried printWriter turning into a bufferedWriter.

Your code is writing to the text file and later reading from the same text file. But ... your code doesn't close the writer until the finally section of code so the read happens before the writer closes and consequently the written data, which is buffered, has not been flushed to disk.
The fix is to close the buffered writer before reading from the same file.
Also, you can reduce the amount of state in your program as follows, while also reducing the number of closes you have to do:
BufferedWriter bw = new BufferedWriter(new FileWriter(file, ...));
You might also consider using try-with-resources to auto flush/close your files.

Getting Stream closed when reading/writing to file Java

I'm implementing a small tool in Java. I have a excel document and from every sheet I need to generate a .sql file. I've created an sql file model, which I have to read from for every excel sheet then replace a value and write it back to another .sql file. The problem is I use a for where I loop through my sheets and for every sheet I need to read that sql file, modify it and export it somewhere else. I get a "Stream closed" error, and I don't know how to close my buffer and/or my InputStream properly. Can you guys help me out with this ?
This is my code:
This gets everything from the file and converts it to a String
public String getString(InputStream is) throws IOException {
BufferedReader reader = null;
StringBuilder sb = new StringBuilder();
String line;
try {
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
sb.append(line + System.lineSeparator());
}
} catch (IOException ex) {
ex.printStackTrace();
}
return sb.toString();
}
This is used to export the file
public void exportFile(String text, String path, String name, String extension) {
BufferedWriter output = null;
try {
File sqlFile = new File(path + name + extension);
output = new BufferedWriter(new FileWriter(sqlFile));
output.write(text);
} catch (IOException e) {
e.printStackTrace();
logger.severe("Unable to write to file!\n");
} finally {
if (output != null) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
logger.severe("Unable to close buffer\n");
}
}
}
}
And this a the part of my run() method, which uses the code above:
ClassLoader loader = this.getClass().getClassLoader();
InputStream createTableInputStream = loader.getResourceAsStream("val_table_create.sql");
if (createTableInputStream == null) {
logger.severe("No tempalte found for creating table!\n");
return;
}
List<Sheet> bookSheets = getSheets(book);
for (Sheet sheet : bookSheets) {
setHeader(table, sheet);
String exportText = getString(createTableInputStream);
exportText = exportText.replaceAll(TABLE_NAME, tableName);
// exportText = exportText.replaceAll(VAL_DATA_TYPE, valDataType);
// exportText = exportText.replaceAll(MSG_TEXT_DATA_TYPE, messageDataType);
exportFile(exportText, absoluteWorkspacePath + File.separator + outputPath + File.separator, tableName, ".sql");
}
if (createTableInputStream != null) {
createTableInputStream.close();
}

The Problem is in this method:
public String getString(InputStream is) throws IOException {
You close the the reader and stream at the end. (When you close the reader the streams in it are automatic close.
Edit: You should close the reader. getString(InputStream is) throws IOException returns always the same String or? Read it before you go in the loop and reuse the String everytime.
String exportText = getString("val_table_create.sql");
for (Sheet sheet : bookSheets) {
setHeader(table, sheet);
String newExportText = exportText.replaceAll(TABLE_NAME, tableName);
messageDataType);
exportFile(newExportText, absoluteWorkspacePath + File.separator + outputPath + File.separator, tableName, ".sql");
}
Change your getString Method to this:
public String getString(String resourceName) throws IOException {
BufferedReader reader = null;
StringBuilder sb = new StringBuilder();
String line;
try {
InputStream createTableInputStream reader.getResourceAsStream(resourceName);
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
sb.append(line + System.lineSeparator());
}
} catch (IOException ex) {
ex.printStackTrace();
}
return sb.toString();
}
and close there all the streams. Now you have one place where you load your file.

createTableInputStream will be closed for the first time you call getString method so for next sheet in loop you will get stream closed.
It's a better practice to close the stream in the method who created it. You should close the stream in run method instead.

Error in reading file java.io

So i'm trying to read the following string from the text file addToLibrary.txt
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
But when I do i get the following error:
java.io.FileNotFoundException: file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3 (No such file or directory)
Whats odd is that I got that string from a fileChooser using this method:
public static void addToLibrary(File f) {
String fileName = "addToLibrary.txt";
try {
FileWriter filewriter = new FileWriter(fileName, true);
BufferedWriter bufferedWriter = new BufferedWriter(filewriter);
bufferedWriter.newLine();
bufferedWriter.write(f.toURI().toString());
System.out.println("Your file has been written");
bufferedWriter.close();
} catch (IOException ex) {
System.out.println(
"Error writing to file '"
+ fileName + "'");
} finally {
}
}
An even stranger error is that my file reader can read things in another folder but not anything in iTunes Media.
I attempt to read all the files in the different folders with the following method:
public void getMusicDirectory() {
int index = 0;
try {
File[] contents = musicDir.listFiles();
//System.out.println(contents[3].toString());
for (int i = 0; i < contents.length; i++) {
//System.out.println("----------------------------------------"+contents.length);
String name = contents[i].getName();
//System.out.println(name);
if (name.indexOf(".mp3") == -1) {
continue;
}
FileInputStream file = new FileInputStream(contents[i]);
file.read();
System.out.println(contents[i].toURI().toString());
songsDir.add(new Song((new MediaPlayer(new Media(contents[i].toURI().toString()))), contents[i]));
file.close();
}
} catch (Exception e) {
System.out.println("Error -- " + e.toString());
}
try(BufferedReader br = new BufferedReader(new FileReader("addToLibrary.txt"))) {
//System.out.println("In check login try");
for (String line; (line = br.readLine()) != null; ) {
FileInputStream file = new FileInputStream(new File(line));
file.read();
songsDir.add(new Song(new MediaPlayer(new Media(line)), new File(line)));
file.close();
}
// line is not visible here.
} catch (Exception e) {
System.out.println("Error reading add to library-- " + e.toString());
}
}
So how can i make this work? why does the first part of the method work but not the second?

You are not having a problem reading the string
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
from a file. That part works fine. Your problem is after that, when you try to open the file with the path:
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
because that's not actually a path; it's a URI (although it can be converted to a path).
You could convert this to a path, in order to open it, but you have no reason to - your code doesn't actually read from the file (apart from the first byte, which it does nothing with) so there's no point in opening it. Delete the following lines:
FileInputStream file = new FileInputStream(contents[i]); // THIS ONE
file.read(); // THIS ONE
System.out.println(contents[i].toURI().toString());
songsDir.add(new Song((new MediaPlayer(new Media(contents[i].toURI().toString()))), contents[i]));
file.close(); // THIS ONE
and
FileInputStream file = new FileInputStream(new File(line)); // THIS ONE
file.read(); // THIS ONE
songsDir.add(new Song(new MediaPlayer(new Media(line)), new File(line)));
file.close(); // THIS ONE

file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3 is not a valid File reference, especially under Windows.
Since you've idendtified the String as a URI, you should treat it as such...
URI uri = URI.create("file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3");
Okay, but, there's no real way to read URI, but you can read a URL, so we need to convert the URI to URL, luckily, this is quite simple...
URL url = uri.toURL();
From there you can use URL#openStream to open an InputStream (which you can wrap in a InputStreamReader) and read the contents of the file, for example...
String imageFile = "file:/...";
URI uri = URI.create(imageFile);
try {
URL url = uri.toURL();
try (InputStream is = url.openStream()) {
byte[] bytes = new byte[1024 * 4];
int bytesRead = -1;
int totalBytesRead = 0;
while ((bytesRead = is.read(bytes)) != -1) {
// Somthing, something, something, bytes
totalBytesRead += bytesRead;
}
System.out.println("Read a total of " + totalBytesRead);
} catch (IOException ex) {
ex.printStackTrace();
}
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
You could, however, save your self a lot of issues and stop using things like f.toURI().toString()); (File#toURI#toString) and simply use File#getPath instead...This would allow you to simply create a new File reference from the String...
Also, your resource management needs some work, basically, if you open it, you should close it. See The try-with-resources Statement for some more ideas

Android FileReader from R.raw.file

Really newbie question:
I have a .csv file that I need to read. I've put it in the raw folder. For convenience, Im' using the http://opencsv.sourceforge.net/ library for reading the file. The library provides this method for creating a CSVReader object:
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
But I don0't get how to point this constructor to my file, since the file in Android is usually referenced like R.raw.file rather than a String address to the file.
Any help would be greatly appreciated.

You want to do something like this -
public void readCSVFromRawResource(Context context)
{
//this requires there to be a dictionary.csv file in the raw directory
//in this case you can swap in whatever you want
InputStream inputStream = getResources().openRawResource(R.raw.dictionary);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try
{
String word;//word
int primaryKey = 0;//primary key
Map dictionaryHash = new HashMap();
while ((word = reader.readLine()) != null)
{
if(word.length() < 7)
{
dictionaryHash.put(primaryKey,word );
primaryKey++;
if(primaryKey % 1000 == 0)
Log.v("Percent load completed ", " " + primaryKey);
}
}
//write the dictionary to a file
File file = new File(DICTIONARY_FILE_NAME);
BufferedOutputStream fos = new BufferedOutputStream(new FileOutputStream(DICTIONARY_FILE_NAME));
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(dictionaryHash);
oos.flush();
oos.close();
Log.v("alldone","done");
}
catch (Exception ex) {
// handle exception
Log.v(ex.getMessage(), "message");
}
finally
{
try
{
inputStream.close();
}
catch (IOException e) {
// handle exception
Log.v(e.getMessage(), "message");
}
}
}

You can use this solution to get a String from the raw resource:
Android read text raw resource file
then use StringReader instead of FileReader with the CSVReader constructor.

Return the text of a file as a string? [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
How to create a Java String from the contents of a file
Is it possible to process a multi-lined text file and return its contents as a string?
If this is possible, please show me how.
If you need more information, I'm playing around with I/O. I want to open a text file, process its contents, return that as a String and set the contents of a textarea to that string.
Kind of like a text editor.

Use apache-commons FileUtils's readFileToString

Check the java tutorial here -
http://download.oracle.com/javase/tutorial/essential/io/file.html
Path file = ...;
InputStream in = null;
StringBuffer cBuf = new StringBuffer();
try {
in = file.newInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line = null;
while ((line = reader.readLine()) != null) {
System.out.println(line);
cBuf.append("\n");
cBuf.append(line);
}
} catch (IOException x) {
System.err.println(x);
} finally {
if (in != null) in.close();
}
// cBuf.toString() will contain the entire file contents
return cBuf.toString();

Something along the lines of
String result = "";
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
dis = new DataInputStream(bis);
while (dis.available() != 0) {
// Here's where you get the lines from your file
result += dis.readLine() + "\n";
}
fis.close();
bis.close();
dis.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;

String data = "";
try {
BufferedReader in = new BufferedReader(new FileReader(new File("some_file.txt")));
StringBuilder string = new StringBuilder();
for (String line = ""; line = in.readLine(); line != null)
string.append(line).append("\n");
in.close();
data = line.toString();
}
catch (IOException ioe) {
System.err.println("Oops: " + ioe.getMessage());
}
Just remember to import java.io.* first.
This will replace all newlines in the file with \n, because I don't think there is any way to get the separator used in the file.