July 2017 – Page 3

Navigation Drawer Item Icon not showing Original Colour

July 18, 2017

Programmatically

yourNavigationView.setItemIconTintList(null);

From XML

<android.support.design.widget.NavigationView
    ...
    app:itemIconTint="@android:color/black" 
    ... />

References
https://stackoverflow.com/questions/31394265/navigation-drawer-item-icon-not-showing-original-colour
https://stackoverflow.com/questions/30621561/disable-icon-colorstatelist-in-navigationview/

Validate EditText Input on Android

July 18, 2017

emailEditText.setError("Invalid Email");

emailEditText.setError(null);//removes error

Custom Icon

Drawable drawable = getDrawable(R.drawable.ic_error_outline_black_24dp);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
users.setError("error", drawable);

References
http://stacktips.com/tutorials/android/edittext-validation-in-android-example
https://stackoverflow.com/questions/13195852/how-can-i-remove-edittext-error-and-request-focus-in-android

Publish Subscribe Sample in RabbitMQ

July 17, 2017

Client -> Producer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        String exchangeName = "logs";

        channel.exchangeDeclare(exchangeName, BuiltinExchangeType.FANOUT);

        int count = 0;

        while (count < 100) {

            String message = new Date().toString();

            String output = String.format(" [#] Sending Log : %s", message);
            System.out.println(output);

            channel.basicPublish(exchangeName, "", null, message.getBytes());

            Thread.sleep(1000);
            count++;
        }

        channel.close();
        connection.close();
    }
}

Server -> Consumer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    showLog();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });
        thread1.start();

        Thread thread2 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    countLong();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });
        thread2.start();
    }

    public static void showLog() throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        String exchangeName = "logs";

        channel.exchangeDeclare(exchangeName, BuiltinExchangeType.FANOUT);
        String queueName = channel.queueDeclare().getQueue();
        channel.queueBind(queueName, exchangeName, "");

        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        Consumer consumer = new DefaultConsumer(channel) {

            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message = new String(body, "UTF-8");

                String output = String.format(" [*] : %s", message);
                System.out.println(output);
            }
        };

        channel.basicConsume(queueName, true, consumer);
    }

    public static void countLong() throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        String exchangeName = "logs";

        channel.exchangeDeclare(exchangeName, BuiltinExchangeType.FANOUT);
        String queueName = channel.queueDeclare().getQueue();
        channel.queueBind(queueName, exchangeName, "");

        System.out.println(" [+] Waiting for messages. To exit press CTRL+C");

        Consumer consumer = new DefaultConsumer(channel) {

            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {

                Statics.countLog++;

                String output = String.format(" [+] : %d", Statics.countLog);
                System.out.println(output);
            }
        };

        channel.basicConsume(queueName, true, consumer);
    }
}

References
https://www.rabbitmq.com/tutorials/tutorial-three-python.html
https://github.com/mhdr/RabbitMQSamples/tree/master/004_PublishSubscribe

RabbitMQ Exchange Types

July 17, 2017

Direct

Fanout

Topic

Headers

References
https://lostechies.com/derekgreer/2012/03/28/rabbitmq-for-windows-exchange-types/

Fair dispatch in RabbitMQ

July 16, 2017

Server : Consumer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message=new String(body,"UTF-8");

                try {
                    doWork(message);
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }
                finally {
                    channel.basicAck(envelope.getDeliveryTag(),false);
                }
            }
        };

        channel.basicConsume(queueName,false,consumer);
    }

    public static void doWork(String message) throws InterruptedException {
        System.out.println(" [x] Received '" + message + "'");

        int sleepTime=new Random().nextInt(2000);

        Thread.sleep(sleepTime);
    }
}

References
https://pupli.net/2017/07/16/work-queues-sample-in-rabbitmq/
https://www.rabbitmq.com/tutorials/tutorial-two-java.html

Message durability in RabbitMQ

July 16, 2017

Server : Consumer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message=new String(body,"UTF-8");

                try {
                    doWork(message);
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }
                finally {
                    channel.basicAck(envelope.getDeliveryTag(),false);
                }
            }
        };

        channel.basicConsume(queueName,false,consumer);
    }

    public static void doWork(String message) throws InterruptedException {
        System.out.println(" [x] Received '" + message + "'");

        int sleepTime=new Random().nextInt(2000);

        Thread.sleep(sleepTime);
    }
}

Client : Producer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {

        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);

        int count = 0;

        while (count < 100) {

            Date date = new Date();

            String message = String.format("%d : %s", count, date.toString());

            channel.basicPublish("", queueName, MessageProperties.PERSISTENT_TEXT_PLAIN,
                    message.getBytes("UTF-8"));
            System.out.println(String.format(" [x] Sent %s", message));

            Thread.sleep(1000);
            count++;
        }
    }
}

References
https://pupli.net/2017/07/16/work-queues-sample-in-rabbitmq/
https://www.rabbitmq.com/tutorials/tutorial-two-java.html

Message acknowledgment in RabbitMQ

July 16, 2017

Server : Consumer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message=new String(body,"UTF-8");

                try {
                    doWork(message);
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }
                finally {
                    channel.basicAck(envelope.getDeliveryTag(),false);
                }
            }
        };

        channel.basicConsume(queueName,false,consumer);
    }

    public static void doWork(String message) throws InterruptedException {
        System.out.println(" [x] Received '" + message + "'");

        int sleepTime=new Random().nextInt(2000);

        Thread.sleep(sleepTime);
    }
}

References
https://pupli.net/2017/07/16/work-queues-sample-in-rabbitmq/
https://www.rabbitmq.com/tutorials/tutorial-two-java.html

Round-robin dispatching in RabbitMQ

July 16, 2017

By default, RabbitMQ will send each message to the next consumer, in sequence. On average every consumer will get the same number of messages. This way of distributing messages is called round-robin.

References
https://pupli.net/2017/07/16/work-queues-sample-in-rabbitmq/
https://www.rabbitmq.com/tutorials/tutorial-two-java.html

Work Queues Sample in RabbitMQ

July 16, 2017

Server : Consumer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message=new String(body,"UTF-8");

                try {
                    doWork(message);
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }
                finally {
                    channel.basicAck(envelope.getDeliveryTag(),false);
                }
            }
        };

        channel.basicConsume(queueName,false,consumer);
    }

    public static void doWork(String message) throws InterruptedException {
        System.out.println(" [x] Received '" + message + "'");

        int sleepTime=new Random().nextInt(2000);

        Thread.sleep(sleepTime);
    }
}

Client : Producer

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {

        String queueName = "queue2";

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName, true, false, false, null);

        int count = 0;

        while (count < 100) {

            Date date = new Date();

            String message = String.format("%d : %s", count, date.toString());

            channel.basicPublish("", queueName, MessageProperties.PERSISTENT_TEXT_PLAIN,
                    message.getBytes("UTF-8"));
            System.out.println(String.format(" [x] Sent %s", message));

            Thread.sleep(1000);
            count++;
        }
    }
}

References
https://www.rabbitmq.com/tutorials/tutorial-two-java.html
https://github.com/mhdr/RabbitMQSamples/tree/master/002_WorkQueues

Hello World Sample in RabbitMQ

July 16, 2017

Server

public class Main {

    public static void main(String[] args) throws IOException, TimeoutException {
        String queueName="Hello";

        ConnectionFactory factory=new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.queueDeclare(queueName,false,false,false,null);

        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");


        Consumer consumer=new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {

                String message=new String(body,"UTF-8");
                System.out.println(" [x] Received '" + message + "'");
            }
        };

        channel.basicConsume(queueName,true,consumer);
    }
}

Client

public class Main {
    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {

        String queueName="Hello";

        ConnectionFactory factory=new ConnectionFactory();
        factory.setHost("localhost");

        Connection connection= factory.newConnection();
        Channel channel= connection.createChannel();

        channel.queueDeclare(queueName,false,false,false,null);


        int count=0;

        while (count<100){
            Date date=new Date();
            String message=String.format("Hello World : %s", date.toString());

            channel.basicPublish("",queueName,null,message.getBytes("UTF-8"));

            System.out.println(" [x] Sent '" + message + "'");
            count++;

            Thread.sleep(1000);
        }

        channel.close();
        connection.close();
    }
}

References
https://www.rabbitmq.com/tutorials/tutorial-one-java.html
https://github.com/mhdr/RabbitMQSamples/tree/master/001_HelloWorld