# Future, CompletableFuture
Below described a problem, when several Futures are submitted and you try to wait for them using `.get()` in a loop. There is no guarantee which will be the order of all these Futures execution. So your main thread will wait until your first Future in a loop will return anything:
## Completable future
```java
Supplier supplier = () -> "Hello";
CompletableFuture future = CompletableFuture.supplyAsync(supplier);
future.join(); // this is a blocking code
```
### ofAll
{% code fullWidth="true" %}
```java
CompletableFuture future1 = CompletableFuture.supplyAsync(new WeatherRetriever()::getWeather);
CompletableFuture future2 = CompletableFuture.supplyAsync(new WeatherRetriever()::getWeather);
CompletableFuture future3 = CompletableFuture.supplyAsync(new WeatherRetriever()::getWeather);
CompletableFuture done = CompletableFuture.allOf(future1, future2, future3);
done.thenApply( v -> Stream.of(future1, future2, future3)
// this is kind of blocking, but at this moment all futures are completed
.map(CompletableFuture::join)
).join();
```
{% endcode %}
### Composing results of futures
{% code fullWidth="true" %}
```java
CompletableFuture jumpFuture = CompletableFuture.supplyAsync(Jumper::jump);
CompletableFuture swimFuture = CompletableFuture.supplyAsync(Swimmer::swim);
SportResult result = jumpFuture.thenCompose(
jumpResult -> swimFuture.thenApply(
swimResult -> new SportResult(jumpResult, swimResult)
)
).join();
```
{% endcode %}
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://amartyushov.gitbook.io/tech/programming-languages/java/multithreading/future-completablefuture.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.