(Java) How to Download Messages in MessageSet One at a Time

If a message set contains a huge number of emails, it's NOT a good idea to try to download all at once into an email bundle using a method such as FetchBundle. It's better to iterate over the messages in the set to download one by one.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkImap imap = new CkImap();

    // Connect using TLS.
    imap.put_Ssl(true);
    imap.put_Port(993);
    boolean success = imap.Connect("imap.example.com");
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Authenticate
    success = imap.Login("email_account_login","email_account_password");
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Search for messages and return a set of matching messages.
    // (This example will simply search for ALL messages.)
    boolean fetchUids = true;
    CkMessageSet messageSet = imap.Search("ALL",fetchUids);
    if (imap.get_LastMethodSuccess() != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    System.out.println("Number of messages = " + messageSet.get_Count());

    int i = 0;
    while (i < messageSet.get_Count()) {
        CkEmail email = imap.FetchSingle(messageSet.GetId(i),fetchUids);
        if (imap.get_LastMethodSuccess() != true) {
            System.out.println(imap.lastErrorText());

            return;
            }

        System.out.println(email.ck_from() + "; " + email.subject());

        i = i+1;
        }

    System.out.println("OK");
  }
}