How to create a completed future in java

Question

What is the best way to construct a completed future in Java? I have implemented my own CompletedFuture below, but was hoping something like this that already exists.

public class CompletedFuture<T> implements Future<T> {     private final T result;      public CompletedFuture(final T result) {         this.result = result;     }      @Override     public boolean cancel(final boolean b) {         return false;     }      @Override     public boolean isCancelled() {         return false;     }      @Override     public boolean isDone() {         return true;     }      @Override     public T get() throws InterruptedException, ExecutionException {         return this.result;     }      @Override     public T get(final long l, final TimeUnit timeUnit) throws InterruptedException, ExecutionException, TimeoutException {         return get();     } } 

Answer 1

In Java 8 you can use the built-in CompletableFuture:

 Future future = CompletableFuture.completedFuture(value); 

Answer 2

Apache Commons Lang defines similar implementation that is called ConstantFuture, you can get it by calling:

Future<T> future = ConcurrentUtils.constantFuture(T myValue);