I am doing a quiz app in Android studio using Kotlin. I am fetching data from an API and showing it in an activity. Now I am implementing a progressBar that indicates how much time to answer each question. This is my function to fetch from API:
private fun fetch(){
val theme = intent.getIntExtra("sport", 21)
val difficulty = intent.getStringExtra("medium")
val url = "https://opentdb.com/api.php?amount=10&category=21&difficulty=medium&type=multiple"
val request = Request.Builder()
.url(url)
.build()
client.newCall(request).enqueue(object: Callback {
override fun onResponse(call: Call, response: Response) {
val body = response.body?.string()
val gson = GsonBuilder().create()
val triviaRequest = gson.fromJson(body, TriviaRequest::class.java)
val result = triviaRequest.results[0]
val question = result.question.toSpanned()
val questionCategory = result.category.toSpanned()
val correctAnswer = result.correct_answer.toSpanned()
val incorrectAnswer1 = result.incorrect_answers[0].toSpanned()
val incorrectAnswer2 = result.incorrect_answers[1].toSpanned()
val incorrectAnswer3 = result.incorrect_answers[2].toSpanned()
val questions = listOf(
correctAnswer,
incorrectAnswer1,
incorrectAnswer2,
incorrectAnswer3
)
shuffle(questions)
runOnUiThread {
val button1 = findViewById<Button>(R.id.alternative1)
val button2 = findViewById<Button>(R.id.alternative2)
val button3 = findViewById<Button>(R.id.alternative3)
val button4 = findViewById<Button>(R.id.alternative4)
questionText.text = question
themeText.text = questionCategory
button1.text = questions[0]
button1.isEnabled = true
button2.text = questions[1]
button2.isEnabled = true
button3.text = questions[2]
button3.isEnabled = true
button4.text = questions[3]
button4.isEnabled = true
button1.setOnClickListener {
button1.isClickable = false
if (button1.text == correctAnswer) {
score += 1
fetch()
} else {
button1.text = "---"
}
}
button2.setOnClickListener {
button2.isClickable = false
if (button2.text == correctAnswer) {
score += 1
fetch()
} else {
button2.text = "---"
}
}
button3.setOnClickListener {
button3.isClickable = false
if (button3.text == correctAnswer) {
score += 1
fetch()
} else {
button3.text = "---"
}
}
button4.setOnClickListener {
button4.isClickable = false
if (button4.text == correctAnswer) {
score += 1
fetch()
} else {
button4.text = "---"
}
}
}
response.close()
}
override fun onFailure(call: Call, e: IOException) {
e.printStackTrace()
}
})
}
And this is how I show the progressBar:
val fetch = runCatching { fetch() }
if(fetch.isSuccess) {
val handler = Handler()
Thread(Runnable {
while (progressCount < 100) {
progressCount += 1
try {
Thread.sleep(50)
} catch (e: InterruptedException) {
e.printStackTrace()
}
handler.post {
progressBar.progress = progressCount
}
}
}).start()
}
}
The problem now is that as soon as the activity starts, my progressBar starts showing but the questions has not appeared yet. My question is how can I know when my fetch function has finished executing? so that I can show the progressBar?
Thanks!
You can look into kotlin coroutines and use suspend functions, or you can use a callback like this:
fun fetch (callback: ()->Unit) { // take callback param
... // do the stuff
callback() // call the callback on complete
}
fetch {
// Done fetching here, execute your code inside this
}