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Java Lambda expression help

Posted on 2016-07-25
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Last Modified: 2016-07-26
Hello there,

I am going through a tutorial on Vert.x and came across this lambda code which I want to replace it with ordinary code i.e. without using lambda expression. Can somebody please help me to replace this lambda expression so i know what is going on

public class MyFirstVerticle extends AbstractVerticle
{
	@Override
	public void start(Future<Void> fut)
	{
		vertx.createHttpServer().requestHandler(r -> {
			r.response().end("<h1>Hello from my first " + "Vert.x 3 application</h1>");
		}).listen(8080, result -> {
			if (result.succeeded())
			{
				fut.complete();
			} else
			{
				fut.fail(result.cause());
			}
		});
	}
}

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Question by:zolf
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6 Comments
 
LVL 35

Accepted Solution

by:
mccarl earned 300 total points
ID: 41728836
Something like this.... (untested but should give you the idea)

public class MyFirstVerticle extends AbstractVerticle
{
	@Override
	public void start(Future<Void> fut)
	{
		vertx.createHttpServer().requestHandler(r -> {
			r.response().end("<h1>Hello from my first " + "Vert.x 3 application</h1>");
		}).listen(8080, new Handler<AsyncResult<HttpServer>>() {
                     public void handle(AsyncResult<HttpServer> result) {
			if (result.succeeded())
			{
				fut.complete();
			} else
			{
				fut.fail(result.cause());
			}
                    }
		});
	}
}

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Author Comment

by:zolf
ID: 41728927
thanks for your comments, what about the r parameter.can you also please tell me what that r is
0
 
LVL 86

Assisted Solution

by:CEHJ
CEHJ earned 200 total points
ID: 41728950
I think you might find it more like this (again untested)

        HttpServer server = vertx.createHttpServer();
        server.listen(8080,
            new Handler<AsyncResult<HttpServer>>() {
                public void handle(AsyncResult<HttpServer> result) {
                    if (result.succeeded()) {
                        fut.complete();
                    } else {
                        fut.fail(result.cause());
                    }
                }
            });
    }

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Has to be said though - if the examples use FP then if you find you're having to translate things back to 'old style' code then you're probably using the wrong API
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LVL 35

Assisted Solution

by:mccarl
mccarl earned 300 total points
ID: 41728961
Oops, sorry I missed that one, although it shouldn't be too hard to apply similar logic to what I did the first time...

public class MyFirstVerticle extends AbstractVerticle
{
	@Override
	public void start(Future<Void> fut)
	{
		vertx.createHttpServer().requestHandler(new Handler<HttpServerRequest>() {
                    public void handle(HttpServerRequest r) {
			r.response().end("<h1>Hello from my first " + "Vert.x 3 application</h1>");
		}}).listen(8080, new Handler<AsyncResult<HttpServer>>() {
                     public void handle(AsyncResult<HttpServer> result) {
			if (result.succeeded())
			{
				fut.complete();
			} else
			{
				fut.fail(result.cause());
			}
                    }
		});
	}
}

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Author Closing Comment

by:zolf
ID: 41729002
cheers
0
 
LVL 35

Expert Comment

by:mccarl
ID: 41729516
You're welcome
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