https://github.com/yannickdot/promiser-java

A lightweight implementation of promises in Java
https://github.com/yannickdot/promiser-java

Last synced: about 6 hours ago
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A lightweight implementation of promises in Java

• Host: GitHub
• URL: https://github.com/yannickdot/promiser-java
• Owner: YannickDot
• License: mit
• Created: 2015-10-12T09:43:59.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2015-10-15T08:45:09.000Z (about 9 years ago)
• Last Synced: 2024-04-18T12:56:16.430Z (7 months ago)
• Language: Java
• Size: 126 KB
• Stars: 9
• Watchers: 5
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Promiser-java

A lightweight implementation of [Promises/A+](https://promisesaplus.com) specification, inspiration taken from JavaScript.

## Requirements

This library is written using Java 8 syntax.

Let's embrace the future ! 😄

To use this into Java 7, 6 and 5 projects, don't forget to install [retrolambda](https://github.com/orfjackal/retrolambda) by [@orfjackal](https://github.com/orfjackal).

### Usage

You can create a Promiser object like this :

``` java

Promiser p = new Promiser((Resolver resolve, Rejecter reject) -> {

  // Place your asynchronous process here, and make sure

  // to trigger resolve.run() or reject.run() when needed.

});

```

`` is the type of the result returned in case of success and `` is the type of the result returned in case of error.

You can handle result and error cases like this now :

```java

p.success((T result) -> {

  // Handle success here

})

.error((U err) -> {

  // Handle error here

})

```

---

### Example

For example let's mock an asynchronous process using a Timer :

``` java

Promiser p = new Promiser((Resolver resolve, Rejecter reject) -> {

  int DELAY = 500;

  new Timer().schedule(new TimerTask() {

      @Override

      public void run() {

  	     resolve.run("I'm done !"); //resolving

         reject.run(404); //rejecting

      }

  }, DELAY);

});

```

Now we can handle the success or the error of this promise using the `.success()` and `.error()` callbacks :

``` java

p.success((String result) -> {

  // Handle success here

})

.error((Integer err) -> {

  // Handle failure here

})

```

## Next step

* Make a Promiser instance "thenable" so we can have a `.then()` and `.catch()` callbacks and provide an asynchronous flow control using `.then()` like this :

```java

  p.then(...)

  .then(...)

  .then(...)

  .catch(...)

```