A utility class I wrote that I keep coming back to. A class like this was added in Java 8 (https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html ), but if that's not an option, you've got this.

CompletionFuture.java

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Add a Future object that doesn't involve Runnables or anything fancy.
 * It allows for checking for completion, waiting until completion, and getting the value.
 * Nice and simple.
 *
 * @param <V>
 */
public class CompletionFuture<V> implements Future<V> {
    private boolean complete;
    private V value;
    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        return false;
    }

    @Override
    public boolean isCancelled() {
        return false;
    }

    @Override
    public boolean isDone() {
        return complete;
    }

    @Override
    public synchronized V get() throws InterruptedException, ExecutionException {
        if (!complete) {
            wait();
        }
        return value;
    }

    @Override
    public synchronized V get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
        if (!complete) {
            wait(unit.toMillis(timeout));
        }
        return value;
    }

    public synchronized void complete(V value) {
        this.value = value;
        complete = true;
        this.notifyAll();
    }
}