Develop Reference

Java - Delete file after reading from it

I am trying to figure out why my inputFile.delete() will not delete the file. After looking at numerous topics it looks like something is still using the file and hence it won't delete. But I can't figure it out. What am I missing??
File inputFile = new File("data/Accounts.txt");
File tempFile = new File("data/tmp.txt");
try {
tempFile.createNewFile();
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String line;
int i = 0;
for (User u : data) {
String toRemove = getIDByUsername(username);
while ((line = reader.readLine()) != null) {
if (line.contains(toRemove + " ")) {
line = (i + " " + username + " " + getStatusByUsername(username) + " " + password);
}
writer.write(line + "\n");
i++;
}
}
reader.close();
writer.close();
} catch (FileNotFoundException e) {
ex.FileNotFound();
} catch (IOException ee) {
ex.IOException();
} finally {
inputFile.delete();
tempFile.renameTo(inputFile);
}

You can have that much shorter and easier by using java.nio:
public static void main(String[] args) {
// provide the path to your file, (might have to be an absolute path!)
Path filePath = Paths.get("data/Accounts.txt");
// lines go here, initialize it as empty list
List<String> lines = new ArrayList<>();
try {
// read all lines (alternatively, you can stream them by Files.lines(...)
lines = Files.readAllLines(filePath);
// do your logic here, this is just a very simple output of the content
System.out.println(String.join(" ", lines));
// delete the file
Files.delete(filePath);
} catch (FileNotFoundException fnfe) {
// handle the situation of a non existing file (wrong path or similar)
System.err.println("The file at " + filePath.toAbsolutePath().toString()
+ " could not be found." + System.lineSeparator()
+ fnfe.toString());
} catch (FileSystemException fse) {
// handle the situation of an inaccessible file
System.err.println("The file at " + filePath.toAbsolutePath().toString()
+ " could not be accessed:" + System.lineSeparator()
+ fse.toString());
} catch (IOException ioe) {
// catch unexpected IOExceptions that might be thrown
System.err.println("An unexpected IOException was thrown:" + System.lineSeparator()
+ ioe.toString());
}
}
This prints the content of the file and deletes it afterwards.
You will want to do something different instead of just printing the content, but that will be possible, too ;-) Try it...

I am trying to figure out why my inputFile.delete() will not delete the file.
That's because the old file API is crappy specifically in this way: It has no ability to tell you why something is not succeeding. All it can do, is return 'false', which it will.
See the other answer, by #deHaar which shows how to do this with the newer API. Aside from being cleaner code and the newer API giving you more options, the newer API also fixes this problem where various methods, such as File.delete(), cannot tell you the reason for why it cannot do what you ask.
There are many, many issues with your code, which is why I strongly suggest you go with deHaar's attempt. To wit:
You aren't properly closing your resources; if an exception happens, your file handlers will remain open.
Both reading and writing here is done with 'platform default encoding', whatever that might be. Basically, never use those FileReader and FileWriter constructors. Fortunately, the new API defaults to UTF_8 if you fail to specify an encoding, which is more sensible.
your exception handling is not great (you're throwing away any useful messages, whatever ex.FileNotFound() might be doing here) - and you still try to delete-and-replace even if exceptions occur, which then fail, as your file handles are still open.
The method should be called getIdByUsername
Your toRemove string is the same every time, or at least, the username variable does not appear to be updated as you loop through. If indeed it never updates, move that line out of your loop.

Send Email from Java with default mail client

I have Java code, that should send emails.
The default mail client opens correctly and also the receiver as well as the subject is smoothly set, but the body is not set. No body is shown. Here's my code:
public void emailOhneStandort() throws URISyntaxException {
try {
composeEmail("benjamin.koubik#daimler.com", "Thanks for the snippet!",
"Hello Raffael,\r\nthis mail was initiated by Java.");
} catch (Exception err) {
err.printStackTrace();
}
System.out.println("Done!");
}
public static void composeEmail(String receiver, String subject, String body) throws Exception {
String mailto = "mailTo:" + receiver;
mailto += "?subject=" + uriEncode(subject);
mailto += "&body=" + uriEncode(body);
String cmd = "";
String os = System.getProperty("os.name").toLowerCase();
if (os.contains("win")) {
cmd = "cmd.exe /c start " + mailto;
} else if (os.contains("osx")) {
cmd = "open " + mailto;
} else if (os.contains("nix") || os.contains("aix") || os.contains("nux")) {
cmd = "xdg-open " + mailto;
}
// Call default mail client with paramters
Runtime.getRuntime().exec(cmd);
}
private static String uriEncode(String in) {
String out = new String();
for (char ch : in.toCharArray()) {
out += Character.isLetterOrDigit(ch) ? ch : String.format("%%%02X", (int) ch);
}
return out;
}

From trying on Windows, I find that I need to escape the & with a ^.
So, if I do this:
C:\>start mailto:test#example.com?subject=foo&body=bar
I get the following error:
'body' is not recognized as an internal or external command, operable program or batch file.
and my email client opens with the subject populated but not the body.
If I do this:
C:\>start mailto:test#example.com?subject=foo^&body=bar
then it works as expected.
I daresay the equivalent will happen in other environments, but can't test that at the moment.
For the record, it seems worth adding that this is a bit of an odd requirement, and if it's something you're doing for production code that will be used by anyone other than yourself, it's probably not the best approach!

Start user's standard mail client with attachment pre-attached

I'm looking for a way that my application can call the user's standard mail application (e.g. Outlook, Thunderbird, etc.). And give it an recipient address, the email text and an attachment.
So, basically the standard email application should pop up have the email ready for me (with recipient, text and attachment) and all that is left to do for me is pressing "send" in my outlook, thunderbird etc.
I've been googling for a while now, but I couldn't find a real solution.
I've been looking into mapi a bit but it seems like 1. it's deprecated and 2. it's mainly built for outlook.
Any help/suggestions/solutions greatly appreciated!
Edit: I have seen the question Start Mail-Client with Attachment but no working answer was provided there and also the question is more than 3 years old.
Edit: Other languages would be ok, too. Has to work on Windows XP, Vista, 7, 8 (both 32 and 64 bit)
UPDATE: It seems to be more difficult than I have thought it to be.
I've been looking into JMAPI, which apparently only works for 32bit Systems.
I've also seen the solutions on codeproject.org (here and here), but I somehow couldn't get them to work.
Now I'm trying to do it with command line:
1. Read user's default mail client
2. Call a batch file according to the email client. (Yes you have to write a batch file for every common mail client.
Example for outlook:
"outlook.exe" /a "F:\test.png" /m "test.test#test.test&cc=test#test.test&subject=subject123&body=Hello, how are you%%3F%%0D%%0Anew line"
--> see my provided answer for futher info on that method

So...
After days of research I gave up to get a general solution.
I came up with a solution working at least for the two most common clients (Thunderbird & Outlook)
My solution is basically calling the application from command line.
For those interested, here is my solution: (I haven't tested it cross platform - works on my old XP laptop though)
import java.io.IOException;
/*
:: Punctuation Hexadecimal equivalent
:: ----------------------------------------------
:: Space ( ) %20
:: Comma (,) %2C
:: Question mark (?) %3F
:: Period (.) %2E
:: Exclamation point (!) %21
:: Colon (:) %3A
:: Semicolon (;) %3B
:: Line feed %0A --> New line %0D%0A
:: Line break (ENTER key) %0D --> New line %0D%0A
*/
public class Main {
static String test = "hi";
private static String attachment;
private static String to;
private static String cc;
private static String subject;
private static String body;
public static void main (String[] args){
attachment = "F:\\pietquest.png";
to = "test#test.de";
cc = "a.b#c.de";
subject = "TestSubject 123";
body = "Hi, what\'s going on%0D%0Anew line";
body = replace(body);
subject = replace(subject);
String[] value = WindowsRegistry.readRegistry("HKEY_LOCAL_MACHINE\\SOFTWARE\\Clients\\Mail", "");
if (value[10].contains("Thunderbird")){
System.out.println("Thunderbird");
String[] pfad = WindowsRegistry.readRegistry("HKEY_LOCAL_MACHINE\\SOFTWARE\\Clients\\Mail\\Mozilla Thunderbird\\shell\\open\\command", "");
String Pfad = pfad[10] + " " + pfad[11];
String argument = Pfad + " /compose \"to=" + to + ",cc=" + cc + ",subject=" + subject + ",body=" + body + ",attachment=" + attachment + "\"";
// System.out.println(argument);
try {
Runtime.getRuntime().exec(argument);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else if (value[10].contains("Outlook")){
System.out.println("Outlook");
String[] pfad = WindowsRegistry.readRegistry(
"HKEY_LOCAL_MACHINE\\SOFTWARE\\Clients\\Mail\\Microsoft Outlook\\shell\\open\\command", "");
String Pfad = pfad[10];
String argument = Pfad + " /a " + attachment + " /m \"" + to
+ "&cc=" + cc + "&subject=" + subject + "&body=" + body + "\"";
// System.out.println(argument);
try {
Runtime.getRuntime().exec(argument);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static String replace(String toReplace){
toReplace = toReplace.replace(" ", "%20");
toReplace = toReplace.replace(",", "%2C");
toReplace = toReplace.replace("?", "%3F");
toReplace = toReplace.replace(".", "%2E");
toReplace = toReplace.replace("!", "%21");
toReplace = toReplace.replace(":", "%3A");
toReplace = toReplace.replace(";", "%3B");
return toReplace;
}
}
and this is the Windows Registry Class: (got that from here)
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
public class WindowsRegistry {
/**
*
* #param location path in the registry
* #param key registry key
* #return registry value or null if not found
*/
public static final String[] readRegistry(String location, String key){
try {
// Run reg query, then read output with StreamReader (internal class)
Process process = Runtime.getRuntime().exec("reg query " +
'"'+ location);
StreamReader reader = new StreamReader(process.getInputStream());
reader.start();
process.waitFor();
reader.join();
// Parse out the value
String[] parsed = reader.getResult().split("\\s+");
if (parsed.length > 1) {
return parsed;
}
} catch (Exception e) {}
return null;
}
static class StreamReader extends Thread {
private InputStream is;
private StringWriter sw= new StringWriter();
public StreamReader(InputStream is) {
this.is = is;
}
public void run() {
try {
int c;
while ((c = is.read()) != -1)
sw.write(c);
} catch (IOException e) {
}
}
public String getResult() {
return sw.toString();
}
}

you can use C#: Example C# or java: Example Java
EDIT
You can use Boost for ssl and send email via smtp

Java's System.getRuntime().exec not behaving as if the shell user called it

I am running a java application from the console on an HP-UX machine. In it, I generate some reports, zip them, and then email them. Everything is working, except the email.
I am using the mail binary to send mail from the command line. Since it's HP-UX, it's a bit different than the standard GNU sendmail.
This is the code I'm using to send the mail:
public static void EmailReports(String[] recipients, String reportArchive, String subject){
SimpleDateFormat dateFormat = new SimpleDateFormat("MM-dd-yyyy");
String today = dateFormat.format(new Date());
File tempEmailFile;
BufferedWriter emailWriter;
try {
tempEmailFile = File.createTempFile("report_email_" + today, "msg");
emailWriter = new BufferedWriter(new FileWriter(tempEmailFile));
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not create temporary file.");
return;
}
try {
emailWriter.write("SUBJECT: " + subject + "\n");
emailWriter.write("FROM: " + FROM + "\n");
emailWriter.write(BODY + "\n");
emailWriter.close();
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not write to temporary file.");
}
//read the archive in
try {
FileInputStream archiveIS = new FileInputStream(new File(reportArchive));
OutputStream archiveEncoder = MimeUtility.encode(new FileOutputStream(tempEmailFile, true), "uuencode", Zipper.getArchiveName(reportArchive));
//read archive
byte[] buffer = new byte[archiveIS.available()]; //these should never be more than a megabyte or two, so storing it in memory is no big deal.
archiveIS.read(buffer);
//encode archive
archiveEncoder.write(buffer);
//close both
archiveIS.close();
archiveEncoder.close();
} catch (FileNotFoundException e) {
System.out.println("Failed to send email. Could not find archive to email.");
e.printStackTrace();
} catch (MessagingException e) {
System.out.println("Failed to send email. Could not encode archive.");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not encode archive.");
}
System.out.println("Sending '" + subject + "' email.");
try {
Process p = Runtime.getRuntime().exec("mail me#example.com < " + tempEmailFile.getAbsolutePath());
System.out.println("mail me#example.com < " + tempEmailFile.getAbsolutePath());
StringBuffer buffer = new StringBuffer();
while(p.getErrorStream().available() > 0){
buffer.append((char) p.getErrorStream().read());
}
System.out.println("STDERR: " + buffer.toString());
buffer = new StringBuffer();
while(p.getInputStream().available() > 0){
buffer.append((char) p.getInputStream().read());
}
System.out.println("STDOUT: " + buffer.toString());
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not get access to the shell.");
}
}
When I run the program, and it sends the email, I get a blank email, no subject, no body, no attachment, and it's from the user#hostname from the HP-UX box instead of from the email specified in FROM.
However, when I run the same line that it runs (see the command printed out after I call exec), I get the correct email, from the correct user, with a subject, body, and attachment.
STDOUT and STDERR are both empty. It's almost as if I'm sending mail a blank file, but when I print the file before I call the exec, it's there.
What's going on here?
Edit: Attempts made:
Using Ksh:
try {
String cmd = "mail me#example.com.com < " + tempEmailFile.getAbsolutePath();
Runtime.getRuntime().exec(new String[] {"/usr/bin/ksh", cmd});
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not get access to the shell.");
}
Using STDIN:
try {
System.out.println("mail me#example.com < " + tempEmailFile.getAbsolutePath());
Process p = Runtime.getRuntime().exec("mail me#example.com ");
FileInputStream inFile = new FileInputStream(tempEmailFile);
byte[] byteBuffer = new byte[inFile.available()];
inFile.read(byteBuffer);
p.getOutputStream().write(byteBuffer);
inFile.close();
p.getOutputStream().close();
StringBuffer buffer = new StringBuffer();
while(p.getErrorStream().available() > 0){
buffer.append((char) p.getErrorStream().read());
}
System.out.println("STDERR: " + buffer.toString());
buffer = new StringBuffer();
while(p.getInputStream().available() > 0){
buffer.append((char) p.getInputStream().read());
}
System.out.println("STDOUT: " + buffer.toString());
} catch (IOException e) {
e.printStackTrace();
System.out.println("Failed to send email. Could not get access to the shell.");
}

I strongly suspect the problem is the redirection. That's normally handled by the shell - and there's no shell here.
Either you need to execute the process normally and then get the process's standard input stream and write to it from Java, or (probably simpler) run /bin/sh (or whatever) to get the shell to do the redirection.

Try exec'ing { "ksh", "-c", "mail me#example.com < " + etc }. The -c option tells the shell specifically to parse the next argument as a shell command with possible redirection and so on. Without the -c, ksh follows a heuristic to decide what to do with its command line, and it may not be running the command in the way you want it to.

Split into two lines, just to get better readability:
String cmd = "mail me#example.com < " + tempEmailFile.getAbsolutePath () ;
Process p = Runtime.getRuntime().exec (cmd);
This will look for a program named "mail me#example.com < " + tempEmailFile.getAbsolutePath (). It will not do redirection - for that to do you have to read the output of that process yourself.
Furtermore it will not lookup the path, so you might have to specify the whole path /usr/bin/mail or whatever it is.
And you have to split command and parameters; use an Array of String instead: ("/path/to/prg", "param1", "param2", "foo=bar");
You can use redirection, if you call as program a script, like
String cmd = "/usr/bin/mail me#example.com < " + tempEmailFile.getAbsolutePath () ;
String cmdarr = new String [] {"/bin/bash", "-c", cmd};
Process p = Runtime.getRuntime().exec (cmdarr);
It is shorter than invoking file redirection from Java yourself, more simple but you lose the ability to react sensible on different errors.

IOException doesn't give enough information

My android program isn't working. I am using normal client-server sockets. I have tested my server with telnet and it works fine, but when I try it with my android program, it doesn't work (more details in a second). Here's my code:
Socket s = null;
try
{
String SocketServerAddress = db.getPhSsServerAddress();
Integer SocketServerPort = db.getPhSsServerPort();
s = new Socket(SocketServerAddress, SocketServerPort);
Log.d(MY_DEBUG_TAG, "Setting up Socket: " + SocketServerAddress + ":" + SocketServerPort);
DataOutputStream out = new DataOutputStream(s.getOutputStream());
DataInputStream in = new DataInputStream(s.getInputStream());
Log.d(MY_DEBUG_TAG, "Connected to: " + s.getInetAddress() + " on port " + s.getPort());
out.writeUTF("Helo, Server");
out.flush();
Log.d(MY_DEBUG_TAG, "Bytes written: " + out.size());
String st = in.readUTF();
Log.d(MY_DEBUG_TAG, "SocketServerResponse: " + st);
}
catch (UnknownHostException e)
{
Log.e(MY_ERROR_TAG, "UnknownHostException: " + e.getMessage() + "; " + e.getCause());
}
catch (IOException e)
{
Log.e(MY_ERROR_TAG, "IOException: " + e.getMessage() + "; " + e.getCause() + "; " + e.getLocalizedMessage());
}
finally
{
try {
s.close();
} catch (IOException e) {
Log.e(MY_ERROR_TAG, "IOException on socket.close(): " + e.getMessage() + "; " + e.getCause());
}
}
All I ever get here is a thrown IOException with no message or cause attached. The specific line causing the error is the String st = in.readUTF(). If I comment out that line, my code runs fine (no exceptions thrown), but my server does not acknowledge that any data has been sent to it. And of course I don't get any data back since that line is commented out.
So, how can I figure out what the problem is? Tonight I am going to try and see what is being passed with wireshark to see if that gives any insight.

Is the server using readUTF() and writeUTF() too? writeUTF() writes data in a unique format that can only be understood by readUTF(), which won't understand anything else.
EDIT EOFException means that there is no more data. You should catch it separately and handle it by closing the socket etc. It can certainly be caused spuriously by readUTF() trying to read data that wasn't written with writeUTF().
And deciding it was an IOException when it was really an EOFException means you didn't print out or log the exception itself, just its message. Always use the log methods provided for exceptions, or at least use Exception.toString().

As I remember I had a problem with DataInpuStream some day... try doing so:
in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));