How to generate a Method with Generic Classes in Java?

Wellcome again,

Today I'm going to explain how to generate methods with generic classes in the call in Java.

First of all, I'm going to show you an example:

        public <T> T convertirDesdeXml(Class<T> c, byte[] xml) {

XStream xStream = new XStream();

xStream.alias(c.getSimpleName(), c);

T objecte = (T)xStream.fromXML(new String(xml));

return objecte;

}

This example converts an xml in byte[] format to a generic object.

We have to use a placeholder that is presented with <T> syntax. A placeholder is a String name that represents any object type that you will use in the context (the class, a method, an static call, etc.).

The placeholder <T> indicates that you can use the class T like a generic type in the method.

You can complicate the call like <T extends java.util,Map>. This new example indicates that the placeholder T extends the interface Map or, what is the same, the operator instanceof returns true.

You can complicate the call like <T, K>. In this example you use two placeholder and you can you the number of placeholder you want.

With the placeholder you have your first generic method with generic classes.

Thanks for the read!

Try it and have fun!

Use cases of this.http.get in Angular 2

Hi everybody!!!

Here we comes with news explanations! Today the theme is how to use the sentence this.http.get! When use on one way or another? And why?

The question you have to do is... do you want a Sincron or Asincron call?

A Sincron call is when you want that the process occurs in the main thread. On this way, the sequence of the next process don't occurs until the call finish.

For do a Sincron call, you have to do the call like this:

this.http.get(url).map( data => data.json() )

This sentence will return a json data file. If you want to return a content file (binary or others types) you have to change data.json() call by data.text().

An Asincron call is when you want to create a new thread from the main thread. On this way, the senquence of the next process will continue and our thread will continue on parallel.

For do an Asincron call, you have to do the call like this:

this.http.get(url)

.subscribe( 

  data => this.data = data.json(),

  err => this.handleError,

  () => {console.log('complete call') /*do something when finish*/}

);

This sentence will process an Asincron call and you can do want you want with the data json file obtained on the complete pass. This call is used in the onInit of the component normally and usually loads a data json file necessary for something on the application (a data project information, a data language properties or what you need or want).

I hope you have found interesting this article.

You can ask me any question or doubt!!! And you are free for share them with your friends!!!

Try it and have fun!