Sending an email within a Java Application

Bryan Douglas — Sun, 15 Jul 2018 06:42:58 +0000

Hi all,

I decided to pick up the old textbook and start to learn more about Java (I know, I should understand most of it by this point :D).

I am focusing on the interaction between the application and sending of emails. As I eventually want to port this code to android studio and use it to create an email application for android.

Here is the code:

public static void main(String[] args) {
        // Recipient's email ID needs to be mentioned.
        String to = "example";

        // Sender's email ID needs to be mentioned
        String from = "example";

        // Setting the host and port
        String host = "smtp.gmail.com";
        String port = "465";

        // Get system properties
        Properties properties = System.getProperties();

        // Setup mail server
        properties.setProperty("mail.smtp.host", host);
        properties.setProperty("mail.smtp.port", port);

        properties.setProperty("mail.user", "example");
        properties.setProperty("mail.password", "example");

        // Get the default Session object.
        Session session = Session.getDefaultInstance(properties);

        try {
            // Create a default MimeMessage object.
            MimeMessage message = new MimeMessage(session);

            // Set From: header field of the header.
            message.setFrom(new InternetAddress(from));

            // Set To: header field of the header.
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

            // Set Subject: header field
            message.setSubject("This is the Subject Line!");

            // Now set the actual message
            message.setText("This is actual message");

            // Send message
            Transport.send(message);
            System.out.println("Sent message successfully....");
        } catch (MessagingException mex) {
            mex.printStackTrace();
        }
    }

My code no longer fails to connect or times out, it just continues to run (likely until my system crashes). After stepping through the code - it seems to hang right at

Transport.send(message);

Since it never throws an error, I cannot get an exception code or any details.

If you guys could take a look at my code and point out any mistakes, that'd be awesome.

Thanks!!!

How to use multiple files in C++

Bryan Douglas — Sat, 03 Feb 2018 03:07:37 +0000

When I was a newcomer to the C++ scene, I personally, had a fair bit of trouble trying to figure out how to keep classes separate from the main.cpp file.

So I figured I would pass my knowledge around on here to help others who are starting to learn C++ - we will use a "Person" class as an example.

Technically, you could use a single file to hold the generic "Main" class and the "Person" class - but that would make re-usability difficult to organize and understand. So it is generally a good example to keep classes as finely grained as possible, and by that, I mean a single class per file.

To give you an idea of what it would look like when you have both classes in the same file, turn your attention to the code below:

int main(int argc, char** argv) {
    std::cout << "Hello World" << std::endl;
}

class Person
{
private:
    std::string m_givenname;
    std::string m_familyname;

public:
    Person() {};
    ~Person() {};

};

With the way our code is set up above, we can only access the class inside this one file. Not to mention Visual Studio will throw up a few errors when you attempt to use classes this way. It is inevitable that larger C++ applications will grow to be more than one file, so creating classes that can be expanded easily will be very useful later on when creating more complex software.

There are two files that need to be created (which are simple to create if using Visual Studio), those are a Header file which holds all of the predefined function prototypes - which is similar to an initial planning of the functions names and their arguments; and a CPP file which holds the guts of the functions themselves.

Using our "Person" class as an example again, I will show examples of the files below:

"Person.h" (Header file)

#include <iostream>

class Person
{
private:
    std::string m_givenname;
    std::string m_familyname;

public:
    Person();    //Constructor prototype
    ~Person();   //Destructor prototype
};

"Person.cpp" (CPP File)

#include "Person.h"

Person::Person()
{

}

Person::~Person()
{

}

Now, with this configuration for a class - all you need to do when you wish to use the class is to include a (class name may differ in your situation)

#include "Person.h"

Then just proceed to create an instance the way you usually would.

This prevents the class files from being loaded on every single file the software works with, which will save time and system resources, as you decide when and where to use it.

Forem: Bryan Douglas

Sending an email within a Java Application

How to use multiple files in C++