CompletableFuture allOf method behavior
I have the following piece of java code:
CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 1";
});
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 2";
});
CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 3";
});
boolean isdone = CompletableFuture.allOf(future1, future2, future3).isDone();
if (isdone) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
When I run this code it always prints "Futures are not ready". I am using allOf method here which should wait for all the futures to get completed, but the main thread is not waiting here and priniting the else part. Can someone please help me understand what is going wrong here?
java completable-future
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
add a comment |
I have the following piece of java code:
CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 1";
});
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 2";
});
CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 3";
});
boolean isdone = CompletableFuture.allOf(future1, future2, future3).isDone();
if (isdone) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
When I run this code it always prints "Futures are not ready". I am using allOf method here which should wait for all the futures to get completed, but the main thread is not waiting here and priniting the else part. Can someone please help me understand what is going wrong here?
java completable-future
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
add a comment |
I have the following piece of java code:
CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 1";
});
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 2";
});
CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 3";
});
boolean isdone = CompletableFuture.allOf(future1, future2, future3).isDone();
if (isdone) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
When I run this code it always prints "Futures are not ready". I am using allOf method here which should wait for all the futures to get completed, but the main thread is not waiting here and priniting the else part. Can someone please help me understand what is going wrong here?
java completable-future
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
I have the following piece of java code:
CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 1";
});
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 2";
});
CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {
try {
Thread.sleep(3);
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
return "Result of Future 3";
});
boolean isdone = CompletableFuture.allOf(future1, future2, future3).isDone();
if (isdone) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
When I run this code it always prints "Futures are not ready". I am using allOf method here which should wait for all the futures to get completed, but the main thread is not waiting here and priniting the else part. Can someone please help me understand what is going wrong here?
java completable-future
java completable-future
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
asked Nov 20 '18 at 10:34
Abhilash28AbhiAbhilash28Abhi
1108
1108
add a comment |
add a comment |
1 Answer
1
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oldest
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I am using allOf method here which should wait for all the futures to get completed
That's not what allOf does. It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. It does not, however, wait for that new CompletableFuture to complete.
This means that you should call some method that waits for this CompletableFuture to be completed, at which point all the given CompletableFutures are guaranteed to be complete.
For example:
CompletableFuture<Void> allof = CompletableFuture.allOf(future1, future2, future3);
allof.get();
if (allof.isDone ()) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
Output:
Future result Result of Future 1 | Result of Future 2 | Result of Future 3
answered Nov 20 '18 at 10:42
EranEran
286k37467555
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of theCompletableFuturemethods that does that (such asget()). Just creating theCompletableFuturedoesn't wait for it to complete. Just like creating the original 3CompletableFutures doesn't wait for them to complete.
– Eran
Nov 20 '18 at 11:18
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I am using allOf method here which should wait for all the futures to get completed
That's not what allOf does. It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. It does not, however, wait for that new CompletableFuture to complete.
This means that you should call some method that waits for this CompletableFuture to be completed, at which point all the given CompletableFutures are guaranteed to be complete.
For example:
CompletableFuture<Void> allof = CompletableFuture.allOf(future1, future2, future3);
allof.get();
if (allof.isDone ()) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
Output:
Future result Result of Future 1 | Result of Future 2 | Result of Future 3
answered Nov 20 '18 at 10:42
EranEran
286k37467555
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of theCompletableFuturemethods that does that (such asget()). Just creating theCompletableFuturedoesn't wait for it to complete. Just like creating the original 3CompletableFutures doesn't wait for them to complete.
– Eran
Nov 20 '18 at 11:18
add a comment |
I am using allOf method here which should wait for all the futures to get completed
That's not what allOf does. It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. It does not, however, wait for that new CompletableFuture to complete.
This means that you should call some method that waits for this CompletableFuture to be completed, at which point all the given CompletableFutures are guaranteed to be complete.
For example:
CompletableFuture<Void> allof = CompletableFuture.allOf(future1, future2, future3);
allof.get();
if (allof.isDone ()) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
Output:
Future result Result of Future 1 | Result of Future 2 | Result of Future 3
answered Nov 20 '18 at 10:42
EranEran
286k37467555
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of theCompletableFuturemethods that does that (such asget()). Just creating theCompletableFuturedoesn't wait for it to complete. Just like creating the original 3CompletableFutures doesn't wait for them to complete.
– Eran
Nov 20 '18 at 11:18
add a comment |
I am using allOf method here which should wait for all the futures to get completed
That's not what allOf does. It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. It does not, however, wait for that new CompletableFuture to complete.
This means that you should call some method that waits for this CompletableFuture to be completed, at which point all the given CompletableFutures are guaranteed to be complete.
For example:
CompletableFuture<Void> allof = CompletableFuture.allOf(future1, future2, future3);
allof.get();
if (allof.isDone ()) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
Output:
Future result Result of Future 1 | Result of Future 2 | Result of Future 3
answered Nov 20 '18 at 10:42
EranEran
286k37467555
I am using allOf method here which should wait for all the futures to get completed
That's not what allOf does. It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. It does not, however, wait for that new CompletableFuture to complete.
This means that you should call some method that waits for this CompletableFuture to be completed, at which point all the given CompletableFutures are guaranteed to be complete.
For example:
CompletableFuture<Void> allof = CompletableFuture.allOf(future1, future2, future3);
allof.get();
if (allof.isDone ()) {
System.out.println("Future result " + future1.get() + " | " + future2.get() + " | " + future3.get());
} else {
System.out.println("Futures are not ready");
}
Output:
Future result Result of Future 1 | Result of Future 2 | Result of Future 3
answered Nov 20 '18 at 10:42
EranEran
286k37467555
answered Nov 20 '18 at 10:42
EranEran
286k37467555
answered Nov 20 '18 at 10:42
EranEran
286k37467555
answered Nov 20 '18 at 10:42
EranEran
286k37467555
286k37467555
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of theCompletableFuturemethods that does that (such asget()). Just creating theCompletableFuturedoesn't wait for it to complete. Just like creating the original 3CompletableFutures doesn't wait for them to complete.
– Eran
Nov 20 '18 at 11:18
add a comment |
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of theCompletableFuturemethods that does that (such asget()). Just creating theCompletableFuturedoesn't wait for it to complete. Just like creating the original 3CompletableFutures doesn't wait for them to complete.
– Eran
Nov 20 '18 at 11:18
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
This works but I am still not clear on the behavior of allOf(). You said - It creates a new CompletableFuture that is completed when all of the given CompletableFutures complete. So how do we know that the new CompletableFuture is completed? Does this not mean we can make use of it rather than waiting for it to complete
– Abhilash28Abhi
Nov 20 '18 at 11:06
@Abhilash28Abhi you have to wait for it to complete by calling some of the
CompletableFuture methods that does that (such as get()). Just creating the CompletableFuture doesn't wait for it to complete. Just like creating the original 3 CompletableFutures doesn't wait for them to complete.– Eran
Nov 20 '18 at 11:18
@Abhilash28Abhi you have to wait for it to complete by calling some of the
CompletableFuture methods that does that (such as get()). Just creating the CompletableFuture doesn't wait for it to complete. Just like creating the original 3 CompletableFutures doesn't wait for them to complete.– Eran
Nov 20 '18 at 11:18
add a comment |
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