My question may be too broad and probably the answer is a simple NO, but I have to ask.
Is there any equivalent implementation of (Java 8) streams* in Java 7?
I am familiar with (Java 8) streams but my project requirement is to use Java 7.
In the official API, no.
There is no more public updates for Java 7. If you're a customer, you might still get minor updates, but this not (or very very very unlikely) for back-porting the Stream API.
With a bit of digging you may look at StreamSupport. I've never tested it but apparently its goal is to backport the Stream API to Java 6/7 and if you want to combine it with lambda expressions there's also retrolambda.
final List<Integer> b = list(1, 2, 3).map(add.f(-1)); listShow(intShow).println(b); // [0, 1, 2]
Finally you can look into the Scala's Stream API. As Scala runs also on the JVM, you can mix your code. Maybe it's not exactly what you are looking for but it's worth a try if needed.