Applying for a tech industry job tends to be quite informal, which can vary dramatically depending on the company you choose. However, this doesn’t mean that you shouldn’t prepare properly for an IT job interview and increase your chances of success.

Before you start meetings with a given digital agency, get acquainted with its offer and the projects it has implemented so far. Such knowledge will provide you with an idea about their specifics, scope, and the clients with whom the company has worked. The first person you will have a chance to talk to will probably be the recruiter, whom you can ask about some issues or challenges you are concerned about or aren’t clear for you at this point. Go ahead, ask them and find out the answers during the phone call or at the first meeting.

The employment process in a software house usually consists of several stages. One of them is a technical interview during which you will be asked to perform specific tasks or answer particular questions. I have prepared a few technical questions and topics that you should be prepared for when applying for a Junior Flutter Developer position.


1. What is the difference between var and dynamic? 

Before talking to a recruiter or developer at the company you want to work for, you should prepare to explain the difference between var and dynamic. If you don’t know it yet or you’re not sure, I’ll give you a hint: When you use dynamic, you can change the TYPE and VALUE of a variable. When you use var, you can change the VALUE of a variable, but you can not change the TYPE. 


  dynamic a = ‘text’;

  a = 123; // This will work

  var b = ‘text’;

  b = 123; // This will not compile

2. What is the difference between const and final?

Another essential question and the field where the recruiter can test your knowledge is asking if you know the difference between const and final. The value of const must be known on compile-time while the value of a final is determined at run-time. 

final a = ‘29.03.2021’;

final b =; // This will work

const a = ‘29.03.2021’;

const b =; // This will not compile 

3. What is the difference between Set and List?

The recruiter may ask you many questions to determine if you are familiar with the terminology that a Junior Flutter Developer should know and if you can tell the difference between particular terms. According to that, you may be asked to explain what’s the difference between Set and List.
Set is a collection of objects in which each object can occur only once. In List, the same elements can occur simultaneously.

4. What is the difference between Container and SizedBox?

As I mentioned before, an excellent way to test your knowledge is to see if you know the difference between the specific elements. You should expect to be asked what’s the difference between Container and SizedBox. If you’re unsure how to answer such a question yet, I’ve prepared a short example to explain the difference.

If you don’t provide width or height, the Container will expand to fit the parent’s constraints. At the same time, the SizedBox will have zero width and height. Therefore, SizedBox serves better as a placeholder. On top of that, the Container can take more parameters like decorations or clip behavior. 


5. What are the constructors of ListView, and when to use them?

When applying for a position as a Junior Flutter Developer, you should be prepared that a recruiter or other person testing your technical knowledge may ask you if you know the constructors of ListView and when to use them.

ListView is a widget that allows us to display children one after another in a specific scroll direction. The constructors of ListView are: 

default ListView() – a scrollable, linear array of widgets from an explicit List. Usually used for a small number of children

ListView.builder() – Used for large or infinite lists. Passing the itemCount improves the ability of the ListView to estimate the maximum scroll extent.

ListView.separated() – Similar to ListView.builder() but allows to create custom separators for each item in the list. 

ListView.custom() – Allows to create custom child model. It gives a lot of flexibility and control over the ListView

6. What is the difference between Stateful and Stateless widgets? 

Going back to the differences and similarities, before the interview, you should find out the difference between Stateful and Stateless widgets. 

As the name suggests, Stateful widget holds a state that can be mutated. It allows us to add interactivity to our app. The state is kept in a State object. On the other hand, a Stateless widget is a widget that will never rebuild itself. It’s ideal to use when we have no need to add interactivity to specific user interface parts.

7. What are the Stateful Widget lifecycle methods? 

In the context of the Stateful widgets I mentioned above, you should know a little more and be prepared to answer the following question – what are the Stateful widget lifecycle methods? Here is the answer:

createState() – Creates the State object. Once the State is created, the mounted property is set to true. This assures that the widget is currently in a widget tree.

initState() – After a widget is inserted into a tree, it is executed after State’s constructor. It is called only once when the state is created.  

didChangeDependencies() – Called when a dependency of this State object changes. Rarely used because the build() method will be called immediately after this method. However, it’s very useful in combination with InheritedWidget

build() – In this method, we develop our widget tree. It holds all the widgets and builds them on the screen. It will be executed many times during the widget lifecycle.

didUpdateWidget() – Get’s called when the parent widget changes and the current widget needs to be rebuilt. As an argument, you receive an old widget so you can compare it with the new one.

deactivate() – This one is called in the process of removing a widget from a widget tree.

dispose() – This is called when State is permanently removed from the widget tree. After that, the mounted property is set to false.


8. How can we perform an asynchronous operation in Dart? 

During interviews for Junior Flutter Developers and other technical positions, you can expect questions testing your theoretical knowledge and those verifying your practical skills. You may be asked to provide answers to what you would do if you need to perform an asynchronous operation in Dart.

The asynchronous operation can be performed by returning the Future type from a method. If we add an async keyword to the method declaration, we can use await keyword, which lets us retrieve the desirable result. Under the hood, if async-await keywords Dart uses, .then callback to resolve a Feature. 

9. What are keys in Flutter?

In the context of the last two questions, we will return to the theoretical knowledge, without which it will be difficult for you to perform the assigned tasks. Therefore, when applying for Junior Flutter Developer position, you should know what keys are in Flutter.

Key is an object that can be passed to a widget. This object identifies the widget. Keys are useful when manipulating collections of widgets of the same type.

10. What is the difference between Hot Restart and Hot Reload?

Do Hot Restart and Hot Reload ring a bell to you? If not, before your big day and the interview, prepare in this area. To make it a little easier for you, here’s a quick hint:

Hot Restart will rebuild the app’s entire state, while the Hot Reload updates only the user interface elements. 


Do you want to know more about interview questions for developers at Applover?

Talk to our team!

Become a Junior Flutter Developer

Before meeting with a software house, digital agency, or any other IT company you’d like to work for as a Junior Flutter Developer, I recommend you prepare to answer the above questions. Your knowledge and well preparation can significantly increase the chances of getting the position you want. And if you’re still looking for a place where you’d like to grow as a Flutter Developer, keep checking Applover’s Careers Page because we start new recruitments regularly due to the company’s growth. We might need someone like you right now.