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jdeferred

> 编程语言
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Java Deferred/Promise library similar to JQuery.

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Java Deferred/Promise library similar to JQuery.

JDeferred 2.x

JDeferred is a Java Deferred/Promise library similar to JQuery's Deferred Object.

Inspired by JQuery and Android Deferred Object.

If you are using JDeferred 1.x, see JDeferred 1.x Documentation

Features

  • Deferred object and Promise
  • Promise callbacks
    • .then(…)
    • .filter(…)
    • .pipe(…)
    • .done(…)
    • .fail(…)
    • .progress(…)
    • .always(…)
    • .pipeAlways(…)
  • Multiple promises
    • .when(p1, p2, p3, …).then(…)
    • .race(p1, p2, p3, …).then(…)
    • .settle(p1, p2, p3, …).then(…)
  • Callable and Runnable wrappers
    • .when(new Runnable() {…})
    • .race(new Runnable() {…})
    • .settle(new Runnable() {…})
  • Uses Executor Service
  • Java Generics support
    • Deferred<Integer, Exception, Double> deferred;
    • deferred.resolve(10);
    • deferred.reject(new Exception());
    • deferred.notify(0.80);
  • Android Support
  • Java 8 Lambda friendly
  • Yes it's on Maven Central Repository!

Maven

xml
<dependency>
    <groupId>org.jdeferred.v2</groupId>
    <artifactId>jdeferred-core</artifactId>
    <version>${version}</version>
</dependency>

Gradle

compile 'org.jdeferred.v2:jdeferred-core:${version}'

Find available versions on Maven Central Repository.

Compatibility

Compatibility reports between versions:

  • 1.2.6 to 2.0.0

Quick Examples

Deferred object and Promise

java
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:

java
deferred.resolve("done");
deferred.reject("oops");
deferred.notify("100%");

Filter

Use .filter(...) instead of .then(...) since 2.0.0-Beta2

java
Deferred d = …;
Promise p = d.promise();
Promise filtered = p.filter(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

Use .pipe(...) instead of .then(...) since 2.0.0-Beta2

java
Deferred d = ...;
Promise p = d.promise();

p.pipe(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!

Deferred Manager

java
DeferredManager dm = new DefaultDeferredManager();
Promise p1, p2, p3;
// initialize p1, p2, p3
dm.when(p1, p2, p3)
  .done(…)
  .fail(…)

You can also specify a Executor Service for your need.

DeferredManager dm = new DefaultDeferredManager(myExecutorService);

Runnable and Callable

You can use Callable and Runnable almost like a Promise without any additional work.

java
DeferredManager dm = new DefaultDeferredManager();
dm.when(new Callable<Integer>(){
  public Integer call() {
    // return something
    // or throw a new exception
  }
}).done(new DoneCallback<Integer>() {
  public void onDone(Integer result) {
    ...
  }
}).fail(new FailCallback<Throwable>() {
  public void onFail(Throwable e) {
    ...
  }
});

If you need to notify progress within your Callable or Runnable, you either need to create your own Deferred object and Promise, or you can use DeferredCallable and DeferredRunnable.

Use your own Deferred object

java
final Deferred deferred = ...
Promise promise = deferred.promise();
promise.then(…);
Runnable r = new Runnable() {
  public void run() {
    while (…) {
      deferred.notify(myProgress);
    }
    deferred.resolve("done");
  }
}

Or, extending DeferredRunnable

java
DeferredManager dm = …;
dm.when(new DeferredRunnable<Double>(){
  public void run() {
    while (…) {
      notify(myProgress);
    }
  }
}).then(…);

Wait and WaitSafely

Since 1.0.1

Normally, when using this framework, you would want to do things asynchronously. However, if there is a need to wait for all deferred tasks to finish, you can use Object.wait or Promise.waitSafely methods.

java
Promise p = dm.when(...)
  .done(...)
  .fail(...)

synchronized (p)
  while (p.isPending()) {
    try {
      p.wait();
    } catch (InterruptedException e) { ... }
  }
}

Alternatively, you can use a more simplified shortcut

java
Promise p = dm.when(...)
  .done(...)
  .fail(...)

try {
  p.waitSafely();
} catch (InterruptedException e) {
  ... 
}

Java 8 Lambda

Now this is pretty cool when used with Java 8 Lambda!

java
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()))
);

When

Calls to when with multiple arguments results in a Promise that signals fail on the first rejection or signals done with all computed values.

Success scenario

java
Callable<Integer> c1 = () -> 1;
Callable<Integer> c2 = () -> 2;
Callable<Integer> c3 = () -> 3;
Promise<MultipleResults3<Integer, Integer, Integer>, OneReject<Throwable>, MasterProgress> p = dm.when(c1, c2, c3);
p.done(MultipleResults3<Integer, Integer, Integer> r -> {
  Assert.assertEquals(r.getFirst(), 1);
  Assert.assertEquals(r.getSecond(), 2);
  Assert.assertEquals(r.getThird(), 3);
});

Failure scenario

java
Callable<Integer> c1 = () -> 1;
Callable<Integer> c2 = () -> 2;
Callable<Integer> c3 = () -> throw new RuntimeException("boom!");
Promise<MultipleResults3<Integer, Integer, Integer>, OneReject<Throwable>, MasterProgress> p = dm.when(c1, c2, c3);
p.done(MultipleResults3<Integer, Integer, Integer> r -> Assert.fail("should not be called"))
 .fail(OneReject<Throwable> r -> Assert.assertEquals(r.getReject().getMessage(), "boom!"));

Since 2.0.0

Calls to when with multiple arguments (up to five) will produce results with typesafe getters.

Race

Since 2.0.0

Calls to race with multiple arguments results in a Promise that signals fail on the first rejection or signals done on the first resolution.

Success scenario

java
Callable<Integer> c1 = () -> { Thread.sleep(200); return 1; };
Callable<Integer> c2 = () -> { Thread.sleep(100); return 2; };
Callable<Integer> c3 = () -> { Thread.sleep(200); return 3; };
Promise<OneResult<?>, OneReject<Throwable>, Void> p = dm.race(c1, c2, c3);
p.done(OneResult<?> r -> Assert.assertEquals(r.getResult(), 2));

Failure scenario

java
Callable<Integer> c1 = () -> { Thread.sleep(200); return 1; };
Callable<Integer> c2 = () -> { Thread.sleep(100); throw new RuntimeException("boom!"); };
Callable<Integer> c3 = () -> { Thread.sleep(200); return 3; };
Promise<OneResult<?>, OneReject<Throwable>, Void> p = dm.race(c1, c2, c3);
p.done(OneResult<?> r -> Assert.fail("should not be called")
  .fail(OneReject<Throwable> r -> Assert.assertEquals(r.getReject().getMessage(), "boom!"));

Settle

Since 2.0.0

Calls to settle with multiple arguments results in a Promise that collects all resolutions and rejections.

java
Callable<Integer> c1 = () -> { Thread.sleep(200); return 1; };
Callable<Integer> c2 = () -> { Thread.sleep(100); throw new RuntimeException("boom!"); };
Callable<Integer> c3 = () -> { Thread.sleep(200); return 3; };
Promise<AllValues, Throwable, MasterProgress>, Void> p = dm.race(c1, c2, c3);
p.done(AllValues r -> {
  Assert.assertEquals(r.get(0).getValue(), 1);
  Assert.assertTrue(r.get(1).getValue() instanceof RuntimeException);
  Assert.assertEquals(r.get(2).getValue(), 3);
});

Cancellation Handler

Since 2.0.0

Sometimes a task may be cancelled while its running and would require ti cleanup any resources it may have allocated. You may define a task that implements the org.jdeferred2.CancellationHandler interface or pass and extra argument to DeferredFutureTask with such implementation, for example

java
final DataSource datasource = ...;
class DatabaseTask extends Runnable, CancellationHandler {
  @Override
  public void run() {
    // perform computation with datasource
  }

  @Override
  public void onCancel() {
    try {
      datasource.close();
    } catch(Exception e) {
      throw new IllegalStateException(e);
    }
  }
}

DeferredFutureTask<X> task = new DeferredFutureTask(new DatabaseTask());
dm.when(task).done(...)

You may also pass the CancellationHandler as an additional argument, for example

java
final DataSource datasource = ...;
class DatabaseTask extends Runnable {
  @Override
  public void run() {
    // perform computation with datasource
  }
}

class DatabaseCancellationHandler implements CancellationHandler {
  @Override
  public void onCancel() {
    try {
      datasource.close();
    } catch(Exception e) {
      throw new IllegalStateException(e);
    }
  }
}

DeferredFutureTask<X> task = new DeferredFutureTask(new DatabaseTask(), new DatabaseCancellationHandler());
dm.when(task).done(...)

Groovy

You can also easily use with Groovy!

groovy
@Grab('org.jdeferred.v2:jdeferred-core:2.0.0')
import org.jdeferred2.*
import org.jdeferred2.impl.*

def deferred = new DeferredObject()
def promise = deferred.promise()

promise.done { result ->
  println "done: $result" 
}.fail { rejection ->
  println "fail: $rejection"
}.always { state, result, rejection ->
  println "always"
}

deferred.resolve("done")

Android Support

Since 1.1.0-Beta1

jdeferred-android is now available, and it can be included just like any other Android libraries! It also uses Android Maven plugin and builds apklib file. If you use Android Maven plugin, you can include dependency:

APKLIB with Maven:

xml
<dependency>
  <groupId>org.jdeferred.v2</groupId>
  <artifactId>jdeferred-android</artifactId>
  <version>${version}</version>
  <type>apklib</type>
</dependency>

AAR with Maven:

Since 1.2.0-Beta1

xml
<dependency>
  <groupId>org.jdeferred.v2</groupId>
  <artifactId>jdeferred-android-aar</artifactId>
  <version>${version}</version>
  <type>aar</type>
</dependency>

AAR with Gradle:

compile 'org.jdeferred.v2:jdeferred-android-aar:${version}'
// or
compile 'org.jdeferred.v2:jdeferred-android-aar:${version}@aar'

Find available versions on Maven Central Repository.

jdeferred-andro

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> Details

PublishedAug 1, 2026
UpdatedSep 17, 2026
Category编程语言
PricingOpen source

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