How to get the list of available folders in a mail account using JavaMail

Question

I am using JavaMail API to connect to my personal account. I have list of folders (labels) in my Gmail account which I created + the default folders like Inbox, Drafts etc. How can I list all the available folders (the default and the user created)?

I can access the particular folder using this API: Folder inbox = store.getFolder("Inbox");. Is there any other API to get the list of folders available in a mail account?

Answer 1

Sergey is close, but by default JavaMail's list() does a LIST "" %, which gives you only top-level folders. GMail puts its system folders (All Mail, Drafts, Sent Mail, Spam, Starred, and Trash) under the non-selectable folder [Gmail], so you really need to do a LIST "" * instead. Otherwise, you'll just get back INBOX, [Gmail], and your labels.

Here's some sample code that connects to GMail, fetches the folder list, and prints out the name and message count for each non-\NoSelect folder (i.e. the ones that aren't just hierarchy placeholders, like [Gmail]):

Properties props = System.getProperties();
props.setProperty("mail.store.protocol", "imaps");
try {
    Session session = Session.getDefaultInstance(props, null);
    javax.mail.Store store = session.getStore("imaps");
    store.connect("imap.gmail.com", "<username>@gmail.com", "<password>");
    javax.mail.Folder[] folders = store.getDefaultFolder().list("*");
    for (javax.mail.Folder folder : folders) {
        if ((folder.getType() & javax.mail.Folder.HOLDS_MESSAGES) != 0) {
            System.out.println(folder.getFullName() + ": " + folder.getMessageCount());
        }
    }
} catch (MessagingException e) {
    e.printStackTrace();
}