Encapsulation, Polymorphism, or Inheritance but also learns subtle details of how to use an abstract class and interface ( see here) while solving a problem or designing an application. In order to complete the design, coding, and unit testing of a Vending machine, a candidate needs to be really good in all three departments.īy the way, this kind of real-world problem is also a good exercise to improve your object-oriented analysis and design skills ( see here), which is very important if you want to become a good application developer.īy designing a vending machine in Java or any other object-oriented language, you not only learn basics e.g. One of the key advantages of such Java interviews is that you can test many essential skills or a candidate in one go. In a typical coding interview, you will be given a problem statement to develop a vending machine and within a limited time, usually, 2 to 3 hours you need to produce a design document, working code, and unit test in Java.

How do you design a Vending Machine in Java? is one of the good Java interview questions mostly asked at Senior level Java developer Interviews.

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