Writing a comic adventure in Kotlin

Hello everyone! Today you will find an easy article that will tell you how to write a simple mobile quiz game in Kotlin. Here I will clearly show what Kotlin looks like for mobile development and offer my ideas on how to structure such a project. Well, I will not torment you with graphomania, go ahead! 

Now you will see the skeleton of an idea that burned brightly, but quickly burned out. My designer friend and I came up with the idea of ​​making a simple mobile game in text format. The genre was planned to be adventure, and the mean text had to be fueled by unique pictures in a certain style. Unfortunately, things did not go beyond the skeleton of the application, so I decided to make it public. Suddenly someone will find new thoughts. I'll make a reservation right away that the project can hardly be called a serious decision, and for really large applications, it may be worth considering more complex abstractions. The application should be perceived as a kind of MVP.

Folder structure

First, let's talk about the folder structure. It is unlikely that there will be anything innovative here, but I consider the folder structure in a project to be one of the most important and interesting things in programming. 

2 Activity, .

StartActivity , - (, “” ..).

MainActivity, - GameActivity, , .

Entity . json , , Entity.

dao ( data access object) , . , Runtime, , .

core , . , .

UI , , - . , presenter- activity.

MVP json-, . :

{
 "id": 2,
 "type": "Q",
 "question": "       .   !",
 "answers": [
   {
     "next_question_id":  5,
     "answer": "  "
   },
   {
     "next_question_id":  3,
     "answer": ",    "
   }
 ]
}

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, : 

• Id - . . ,

  
  
  
  
  

• type - . Q ,   "question" . F (Fail) S (Success). , ,

  
  
  
  
  

• question - ,

  
  
  
  
  

• answers - . 0 4 . , F S. , , ,

  
  
  
  
  

JSON assests. , . , , JSON , sqllite. , .

, , , . , . .

, runtime. Store.

public interface Store {
    fun getAllQuestions(): List<Question>

    fun getQuestionById(id: Int): Question

    fun init(context: Context): Store
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . , - . MVP JSON-, , . , , , , sqllite . , - .

class StoreFactory {
    companion object {
        fun getStore(ctx: Context): Store {
            return LocalStore().init(ctx)
        }
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. , . , , ANR. IO - . production , RX. , .

:

class Game {
    private lateinit var store: Store
    private lateinit var question: Question

    fun init(context: Context) {
        this.store = StoreFactory.getStore(context)

        question = store.getQuestionById(1)
    }

    fun isGameEnd(): Boolean {
        return isSuccess() || isFail()
    }

    fun isSuccess(): Boolean {
        return question.isSuccess()
    }

    fun isFail(): Boolean {
        return question.isFail()
    }

    fun chooseAnswer(numberOfAnswer: Int) {
        val answer: Answer = question.getAnswers()[numberOfAnswer - 1]
        question = store.getQuestionById(answer.getNextQuestionId())
    }

    fun getQuestion(): Question {
        return question
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

2 : Store, , , . , ( type F S). , .

. , , . .

(Question.kt). :

fun getAnswers(): List<Answer> {
        val list: MutableList<Answer> = ArrayList(this.answers)
        val shouldAdd: Int = 4 - list.size

        for (i in 1..shouldAdd) {
            list.add(Answer("", -1))
        }

        return list
    }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

List 4 , , 2. id. , . , .

, 4 , . , presenter:

private fun updateView() {
        if (game.isGameEnd()) {
            showEndGame()
            return
        }

        activity.setQuestion(game.getQuestion().getText())

        val answers: List<Answer> = game.getQuestion().getAnswers()
        answers.forEachIndexed {idx, answer -> activity.setAnswer(idx + 1, answer.getText())}
    }

    fun chooseAnswer(number: Int) {
        game.chooseAnswer(number)
        updateView()
    }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, StartActivity, ( ) Intent:

private fun showEndGame() {
        val intent = Intent(activity, StartActivity::class.java).apply {
            putExtra(StartActivity.RESULT_MESSAGE, game.getQuestion().getText())
        }
        activity.startActivity(intent)
    }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, production-ready. , . MVP, , . , :

• . ,

  
  
  
  
  

• UI- , .  

  
  
  
  
  

• ,

  
  
  
  
  

• json - , loader

  
  
  
  
  

• json sqllite

  
  
  
  
  

, .