Porting from C# to Java – The Delegate

The delegate function is kind of cool in C# land. It allows you to pass a bunch of functions as a parameter. Java has a handful of different ways you can do this. I personally like just passing an object that implements Runnable and then have an anonymous inner class that defines the run method. The following is an example in C Sharp code and how I ported it over to Java.

Example

C#

This first class calls the delegate function that passes a series of functions to run to another class.
[csharp]
new RetryPattern(Logger).Execute(delegate
{
var routingKey = myEvent.GetRoutingKey();
IBasicProperties properties = null;
if (durable)
{
properties = bundle.Channel.CreateBasicProperties();
properties.Persistent = true;
}
bundle.Channel.BasicPublish(ExchangeName, routingKey, Mandatory, properties,
Encoding.UTF8.GetBytes(myEvent.GetBody()));
}, delegate
{
ResetOnConnectionError();
CreatePublisher();
});
[/csharp]

These functions are executed using an Action object.
[csharp]
public void Execute(Action action, Action throwHandler = null) {
//Stuff
action(); // Do work here
//More stuff
}
[/csharp]

Java

The way I like to do this in Java is to pass an object that implements Runner. The following two blocks do the same as the above delegate in C#.
This is the anonymous inner class.
[java]
new RetryPattern().execute(new Runnable() {
@Override
public void run() {
String routingKey = myEvent.getRoutingKey();
BasicProperties properties = null;
if (durable) {
properties = new AMQP.BasicProperties().builder()
.deliveryMode(2)
.build();
}
try {
bundle.channel.basicPublish(exchangeName, routingKey, mandatory, properties, myEvent.getBody().getBytes("UTF-8"));
} catch (IOException e) {
e.printStackTrace();
}
}
}, new Runnable() {
@Override
public void run() {
resetOnConnectionError();
createPublisher();
}
});

And this is how it is called elsewhere.
[java]
public void execute(Runnable action, Runnable throwHandler ) {
//Stuff
action.run();
//More Stuff
}
[/java]