Develop Reference

Append list of string to end of text file in Android external storage

I am trying to write an array of string into the external storage of Android emulator. Here is my code:
private void writeToFile(String[] data) {
File workingDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS + "/wordlist.txt");
try (BufferedWriter bw = new BufferedWriter(new FileWriter(workingDir))) {
for (String line : data) {
bw.write(line + "\n");
}
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
It did managed to write each of the item in string array into the text file. However, the next time when I execute this function again, it wipes all the previous existing strings in the text file and replaced them instead. Any ideas on how to keep append new strings to the end of the file?
Thanks!

I solved it already. Basically I need to read all the existing text from the text file, add them to a new list, then append the latest string onto the new list, then proceed to write to the text file.

You can use the append option to append to the existing file without overwriting it.
BufferedWriter bw = new BufferedWriter(new FileWriter(workingDir, true))
The optional true argument sets the file writer to append mode. Also see the answers here.

How to Write text file Java

The following code does not produce a file (I can't see the file anywhere).
What is missing?
try {
//create a temporary file
String timeLog = new SimpleDateFormat("yyyyMMdd_HHmmss").format(
Calendar.getInstance().getTime());
File logFile=new File(timeLog);
BufferedWriter writer = new BufferedWriter(new FileWriter(logFile));
writer.write (string);
//Close writer
writer.close();
} catch(Exception e) {
e.printStackTrace();
}

I think your expectations and reality don't match (but when do they ever ;))
Basically, where you think the file is written and where the file is actually written are not equal (hmmm, perhaps I should write an if statement ;))
public class TestWriteFile {
public static void main(String[] args) {
BufferedWriter writer = null;
try {
//create a temporary file
String timeLog = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
File logFile = new File(timeLog);
// This will output the full path where the file will be written to...
System.out.println(logFile.getCanonicalPath());
writer = new BufferedWriter(new FileWriter(logFile));
writer.write("Hello world!");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
// Close the writer regardless of what happens...
writer.close();
} catch (Exception e) {
}
}
}
}
Also note that your example will overwrite any existing files. If you want to append the text to the file you should do the following instead:
writer = new BufferedWriter(new FileWriter(logFile, true));

I would like to add a bit more to MadProgrammer's Answer.
In case of multiple line writing, when executing the command
writer.write(string);
one may notice that the newline characters are omitted or skipped in the written file even though they appear during debugging or if the same text is printed onto the terminal with,
System.out.println("\n");
Thus, the whole text comes as one big chunk of text which is undesirable in most cases.
The newline character can be dependent on the platform, so it is better to get this character from the java system properties using
String newline = System.getProperty("line.separator");
and then using the newline variable instead of "\n". This will get the output in the way you want it.

In java 7 can now do
try(BufferedWriter w = ....)
{
w.write(...);
}
catch(IOException)
{
}
and w.close will be done automatically

It's not creating a file because you never actually created the file. You made an object for it. Creating an instance doesn't create the file.
File newFile = new File("directory", "fileName.txt");
You can do this to make a file:
newFile.createNewFile();
You can do this to make a folder:
newFile.mkdir();

Using java 8 LocalDateTime and java 7 try-with statement:
public class WriteFile {
public static void main(String[] args) {
String timeLog = DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss").format(LocalDateTime.now());
File logFile = new File(timeLog);
try (BufferedWriter bw = new BufferedWriter(new FileWriter(logFile)))
{
System.out.println("File was written to: " + logFile.getCanonicalPath());
bw.write("Hello world!");
}
catch (IOException e)
{
e.printStackTrace();
}
}
}

You can try a Java Library. FileUtils, It has many functions that write to Files.

It does work with me. Make sure that you append ".txt" next to timeLog. I used it in a simple program opened with Netbeans and it writes the program in the main folder (where builder and src folders are).

The easiest way for me is just like:
try {
FileWriter writer = new FileWriter("C:/Your/Absolute/Path/YourFile.txt");
writer.write("Wow, this is so easy!");
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
Useful tips & tricks:
Give it a certain path:
new FileWriter("C:/Your/Absolute/Path/YourFile.txt");
New line
writer.write("\r\n");
Append lines into existing txt
new FileWriter("log.txt");
Hope it works!

JTextArea txt; txt.getText() skips "\n"

i have some text in TextArea, and i want to save it in file, my code is here:
private void SaveFile() {
try {
String content = txt.getText();
File file = new File(filename);
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(content);
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
but it saves without "\n"; and in new file everything is on one line;
ho can i foresee those "enters" too?
thank you in advance
the problem was because of notepad, so here is solution:
private void SaveFile() {
try {
String content = txt.getText();
content = content.replaceAll("(?!\\r)\\n", "\r\n");
File file = new File(filename);
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(content);
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Thanks for helping

It should work. Try to use a text editor that display the line endings \r and \n and see what comes up.
If you want to be sure that the text file can be open by windows utilities like Notepad that only understand \r\n, you have to normalize it yourself this way:
content = content.replaceAll("(?!\\r)\\n", "\r\n");
This will replace all \n who is not preceded by a \r by the sequence \r\n.

You should use the read() and write() methods provided by the Swing text components. See Text and New Lines for more information.
If you want the output to contain a specific EOL string then you should use the following after creating the Document for your text component:
textComponent.getDocument().putProperty(DefaultEditorKit.EndOfLineStringProperty, "\r\n");

The \ character escapes the next character, as you say \n will create a newline. If you wish to output an actual \, you need to write:
"\n"

You can use a PrintWriter to print new Line to a file . On scanning TextArea's text if the TextArea's text contains "\\n" then use PrintWriter's println() method else make use of simply print() !

You have the content of your TextArea in a String. Now you can split it at newline, then you will get your String[]. Then you can iterate the String[] array and write it in your file:
private void SaveFile() {
try {
String content = txt.getText();
File file = new File(filename);
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
for (String line : content.split("\\n")) {
bw.write(content);
}
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}

TextArea - Any way to get all text?

so I'm designing a text editor. For the Open/Save methods, I'm trying to use a TextArea (it doesn't have to be one, it's just my current method). Now, I have two problems right now:
1) When I load a file, it currently doesn't remove the contents currently in the text editor. For example, if I typed in "Owl", then loaded a file that contained "Rat", it would end up as "OwlRat". To solve this, I plan to use the replaceRange method (again however, it isn't absolute, any suggestions would be great!). However, I must replace all the contents of the text editor, not just selected text, and I can't figure out how to do that. Any tips?
2) Currently, when I load a file, nothing will happen unless I saved that file the same time I ran the application. So, for example, running the program, saving a file, closing the program, running the program again, and then loading the file will give nothing. I know this is because the String x doesn't carry over, but I can't think of anyway to fix it. Somebody suggested Vectors, but I don't see how they would help...
Here is the code for the Open/Save methods:
Open:
public void Open(String name){
File textFile = new File(name + ".txt.");
BufferedReader reader = null;
try
{
textArea.append(x);
reader = new BufferedReader( new FileReader( textFile));
reader.read();
}
catch ( IOException e)
{
}
finally
{
try
{
if (reader != null)
reader.close();
}
catch (IOException e)
{
}
}
}
Save:
public void Save(String name){
File textFile = new File(name + ".txt");
BufferedWriter writer = null;
try
{
writer = new BufferedWriter( new FileWriter(textFile));
writer.write(name);
x = textArea.getText();
}
catch ( IOException e)
{
}
finally
{
try
{
if ( writer != null)
writer.close( );
}
catch ( IOException e)
{
}
}
}

I had this same problem my guy friend, after much thought and research I even found a solution.
You can use the ArrayList to put all the contents of the TextArea and send as parameter by calling the save, as the writer just wrote string lines, then we use the "for" line by line to write our ArrayList in the end we will be content TextArea in txt file.
if something does not make sense, I'm sorry is google translator and I who do not speak English.
Watch the Windows Notepad, it does not always jump lines, and shows all in one line, use Wordpad ok.
private void SaveActionPerformed(java.awt.event.ActionEvent evt) {
String NameFile = Name.getText();
ArrayList< String > Text = new ArrayList< String >();
Text.add(TextArea.getText());
SaveFile(NameFile, Text);
}
public void SaveFile(String name, ArrayList< String> message) {
path = "C:\\Users\\Paulo Brito\\Desktop\\" + name + ".txt";
File file1 = new File(path);
try {
if (!file1.exists()) {
file1.createNewFile();
}
File[] files = file1.listFiles();
FileWriter fw = new FileWriter(file1, true);
BufferedWriter bw = new BufferedWriter(fw);
for (int i = 0; i < message.size(); i++) {
bw.write(message.get(i));
bw.newLine();
}
bw.close();
fw.close();
FileReader fr = new FileReader(file1);
BufferedReader br = new BufferedReader(fr);
fw = new FileWriter(file1, true);
bw = new BufferedWriter(fw);
while (br.ready()) {
String line = br.readLine();
System.out.println(line);
bw.write(line);
bw.newLine();
}
br.close();
fr.close();
} catch (IOException ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(null, "Error in" + ex);
}

There's a lot going on here...
What is 'x' (hint: it's not anything from the file!), and why are you appending it to the text area?
BufferedReader.read() returns one character, which is probably not what you're expecting. Try looping across readline().
Follow Dave Newton's advice to handle your exceptions and provide better names for your variables.
The text file will persist across multiple invocation of your program, so the lack of data has nothing to do with that.
Good luck.

Use textArea.setText(TEXT); rather than append; append means to add on to, so when you append text to a TextArea, you add that text to it. setText on the other hand will set the text, replacing the old text with the new one (which is what you want).
As far as why it's failing to read, you are not reading correctly. First of all, .read() just reads a single character (not what you want). Second, you don't appear to do anything with the returned results. Go somewhere (like here) to find out how to read the file properly, then take the returned string and do textArea.setText(readString);.
And like the others said, use e.printStackTrace(); in all of your catch blocks to make the error actually show up in your console.

Java save multiline string to text file

I am new to Java and trying to save a multi line string to a text file.
Right now, it does work within my application. Like, if I save the file from my application and then open it from my application, it does put a space between lines. However, if I save the file from my app and then open it in Notepad, it is all on one line.
Is there a way to make it show multi line on all programs? Here's my current code:
public static void saveFile(String contents) {
// Get where the person wants to save the file
JFileChooser fc = new JFileChooser();
int rval = fc.showSaveDialog(fc);
if(rval == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
//File out_file = new File(file);
BufferedWriter out = new BufferedWriter(new FileWriter(file));
out.write(contents);
out.flush();
out.close();
} catch(IOException e) {
messageUtilities.errorMessage("There was an error saving your file. IOException was thrown.", "File Error");
}
}
else {
// Do nothing
System.out.println("The user choose not to save anything");
}
}

depending on how you are constructing your string, you may just be running into a line ending problem. Notepad does not support unix line endings (\n only) it only supports windows line endings (\n\r). try opening your saved file using a more robust editor, and/or make sure you are using the proper line endings for your platform. java's system property (System.getProperty("line.separator")) will get you the proper line ending for the platform that the code is running on.
while you're building your string to be saved to the file, rather than explicitly specifying "\n" or "\n\r" (or on the mac "\r") for your line endings, you would instead append the value of that system property.
like so:
String eol = System.getProperty("line.separator");
... somewhere else in your code ...
String texttosave = "Here is a line of text." + eol;
... more code.. optionally adding lines of text .....
// call your save file method
saveFile(texttosave);

Yea as the previous answer mentions the System.getProperty("line.seperator").
your code doesn't show how you created String contents but since you said you were new to java I thought i'd mention that in java concatenating Strings is not nice since it creates a. If you are building the String by doing this:
String contents = ""
contents = contents + "sometext" + "some more text\n"
Then consider using java.lang.StrinBuilder instead
StringBuilder strBuilder = new StringBuilder();
strBuilder.append("sometext").append("somre more text\n");
...
String contents = strBuilder.toString();
Another alternative is to stream what ever your planning to write to a file rather than building a large string and then outputting that.

You could add something like:
contents = contents.replaceAll("\\n","\\n\\r");
if notepad does not display correctly. However you might run into a different problem: at each save/load you will get multiple \r chars. Then to avoid that at load you would have to call the same code above but with reversed parameters. This is really an ugly solution just to get the text to display properly in notepad.

I had this same problem my guy friend, after much thought and research I even found a solution.
You can use the ArrayList to put all the contents of the TextArea for exemple, and send as parameter by calling the save, as the writer just wrote string lines, then we use the "for" line by line to write our ArrayList in the end we will be content TextArea in txt file.
if something does not make sense, I'm sorry is google translator and I who do not speak English.
Watch the Windows Notepad, it does not always jump lines, and shows all in one line, use Wordpad ok.
private void SaveActionPerformed(java.awt.event.ActionEvent evt) {
String NameFile = Name.getText();
ArrayList< String > Text = new ArrayList< String >();
Text.add(TextArea.getText());
SaveFile(NameFile, Text);
}
public void SaveFile(String name, ArrayList< String> message) {
path = "C:\\Users\\Paulo Brito\\Desktop\\" + name + ".txt";
File file1 = new File(path);
try {
if (!file1.exists()) {
file1.createNewFile();
}
File[] files = file1.listFiles();
FileWriter fw = new FileWriter(file1, true);
BufferedWriter bw = new BufferedWriter(fw);
for (int i = 0; i < message.size(); i++) {
bw.write(message.get(i));
bw.newLine();
}
bw.close();
fw.close();
FileReader fr = new FileReader(file1);
BufferedReader br = new BufferedReader(fr);
fw = new FileWriter(file1, true);
bw = new BufferedWriter(fw);
while (br.ready()) {
String line = br.readLine();
System.out.println(line);
bw.write(line);
bw.newLine();
}
br.close();
fr.close();
} catch (IOException ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(null, "Error in" + ex);
}