JarCastingGDeferred
GDeferred is a fork of JDeferred - "Java Deferred/Promise library similar to JQuery's Deferred Object" - reimplemented for GWT.
Features
- Deferred Object and Promise
- Promise callbacks
.then(…).done(…).fail(…).progress(…).always(…)
- Multiple promises (soon!)
.when(p1, p2, p3, …).then(…)
- Java Generics support
Deferred<Integer, Exception, Double> deferred;deferred.resolve(10);deferred.reject(new Exception());deferred.progress(0.80);
- Java 8 Lambda friendly
Quick Examples
Deferred Object and Promise
Deferred deferred = new DeferredObject();
Promise promise = deferred.promise();
promise.done(new DoneCallback() {
public void onDone(Object result) {
...
}
}).fail(new FailCallback() {
public void onFail(Object rejection) {
...
}
}).progress(new ProgressCallback() {
public void onProgress(Object progress) {
...
}
}).always(new AlwaysCallback() {
public void onAlways(State state, Object result, Object rejection) {
...
}
});
With the reference to deferred object, you can then trigger actions/updates:
deferred.resolve("done");
deferred.reject("oops");
deferred.progress("100%");
Filter
Filtering allows one to return a different promise of the same state.
Deferred d = …;
Promise p = d.promise();
Promise filtered = p.then(new DoneFilter<Integer, Integer>() {
public Integer filterDone(Integer result)
return result * 10;
}
});
filtered.done(new DoneCallback<Integer>{
public void onDone(Integer result) {
// result would be original * 10
System.out.println(result);
}
});
d.resolve(3) -> 30.
Pipe
Piping allows one to return a different promise of the any state.
Deferred d = ...;
Promise p = d.promise();
p.then(new DonePipe<Integer, Integer, Exception, Void>() {
public Deferred<Integer, Exception, Void> pipeDone(Integer result) {
if (result < 100) {
return new DeferredObject<Integer, Void, Void>().resolve(result);
} else {
return new DeferredObject<Integer, Void, Void>().reject(new Exception(...));
}
}
}).done(...).fail(...);
d.resolve(80) -> done!
d.resolve(100) -> fail!
Java 8 Lambda
Now this is pretty cool when used with Java 8 Lambda!
dm.when(() -> {
return "Hey!";
}).done(r -> System.out.println(r));
dm.when(
() -> { return "Hello"; },
() -> { return "World"; }
).done(rs ->
rs.forEach(r -> System.out.println(r.getResult()))
);
Documentation
Downloads
GDeferred is currently available at maven central.
Maven
<dependency>
<groupId>io.reinert.gdeferred</groupId>
<artifactId>gdeferred</artifactId>
<version>0.9.0</version>
</dependency>
License
GDeferred is freely distributable under the Apache 2.0 License
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