In Java when writing an array to file, only the last line is written

Question

I am trying to write an array to a file using a loop, but every time I open the text file it only shows the last line. If I write the array directly with a toString it has the extra spaces and array characters I don't want. Here is my code for writing to the array

WriteFile data = new WriteFile(file_namec2g , true);
for (String s : full) {try {
data.writeToFile(s );
} catch (IOException ex) {
Logger.getLogger(CC2LevelManagerUI.class.getName()).log(Level.SEVERE, null, ex);
}
}

Write file is my file writing class. I can post that in another comment if it would be useful. It is one I found on the internet.File_namec2g is the name of the file and the true is if it overwrites or not. So my question is how can I get the array to print line by line into a text file that will show up as such in a program like notepad?

Are you re-creating a `PrintWriter` object each time you call `writeToFile()`? If so, that will discard all changes you have previously made without calling `close()` first. — SamTebbs33, Jul 26 '15 at 22:47
http://stackoverflow.com/questions/2885173/how-to-create-a-file-and-write-to-a-file-in-java — hagrawal7777, Jul 26 '15 at 22:52
For concepts - https://docs.oracle.com/javase/tutorial/essential/io/file.html . Good if you read complete "Basic I/O" in the tutorial .. — hagrawal7777, Jul 26 '15 at 22:52

score 1 · Answer 1 · answered Jul 26 '15 at 23:00

Based on your comment, you are creating a new PrintWriter object each time you call data.writeToFile(). Instead, create the object in the WriteFile constructor and then create a method in WriteFile called save() (or similar) that calls the close() method on the PrintWriter object. Call that method once you have written all of the text in your loop.

WriteFile data = new WriteFile(file_namec2g , true);
for (String s : full) {
try {
    data.writeToFile(s );
} catch (IOException ex) {
    Logger.getLogger(CC2LevelManagerUI.class.getName()).log(Level.SEVERE, null, ex);
}
data.save() // Save the changes to the file

In WriteFile

public void save(){
    pw.close(); // Replace "pw" with the name of the `PrintWriter` object
}

In Java when writing an array to file, only the last line is written

1 Answers1