As you have seen, it's a much more powerful implementation of Java using promise. Java is very powerful when it comes to implementing the promise paradigm.

Actually, Java itself has many powerful features, but when it comes to proper implementation, such frameworks help us out. Since they are community maintained, they have a problem in terms of quality, as you may find nontested and unverified code that can waste your time. However, JDeferred has almost identical implementation, compared to jQuery.