KOTLIN :How To Call a View within a Function Using ViewBinding

user_14048152 0
Viewed 1118

So with the new Kotlin, Android studio update, it is impossible to call views using their respective ID like the norm, hence viewbinding. However, I have been trying to call the said view inside a function using the binding method to no success as it keeps returning an error

below is the code:

class JobActivity : AppCompatActivity() {

private val PROGRESS_MAX = 100
private val PROGRESS_START = 0
private val JOB_TIME = 4000 // ms

private lateinit var job: CompletableJob

private lateinit var binding: ActivityJobBinding
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_job)


    binding = ActivityJobBinding.inflate(layoutInflater)
    setContentView(binding.root)
    binding.jobbutton.setOnClickListener {
        if (!::job.isInitialized  ){
            initjob()
        }
    }

}


fun initjob(){
    binding.jobbutton.setText("StartJob #1")
    binding.textView2.setText("")
    job= Job()
    job.invokeOnCompletion {
        it?.message.let {
            var msg = it
            if (msg.isNullOrBlank()){
                msg ="Uknown cancellation Error"
            }
            println("${job} was cancelled. Reason:$msg")
            showtoast(msg)
        }
    }
    binding.progressBar.max= PROGRESS_MAX
    binding.progressBar.progress= PROGRESS_START

}
fun showtoast(text:String){
    Toast.makeText(this@JobActivity, text,Toast.LENGTH_SHORT).show()
}
  }
fun ProgressBar.startJobOrCancel(job: Job) {
if (this.progress > 0) {
    Log.d(TAG, "${job} is already active. Cancelling...")
    resetjob()
} else {
    binding.jobbutton.setText("StartJob #1")
    Log.d(TAG, "coroutine ${this} is activated with job ${job}.")

}
}

the error occurs here:

enter image description here

please provide precise steps

android-viewbinding kotlin android-view android
3 Answers

@GabrielFranciss

mmm, i think the binding object its not recognized outside the extension function, you must add the binding as a parameter, or, create a lambda function that could be invoked when the extension function executes and concludes.

fun ProgressBar.startJobOrCancel(job:Job, jobStarted: () -> Unit ) {
  when {
    this.progress > 0 -> {
      //log
      resetJob()
    }
    else -> {
      jobFinished()
    }
  }
}

And using the function in the activity/fragment as follows:

  private var job = Job()
  private var scope = CoroutineScope(Dispatchers.Default+job)
  /* inside initJob() ... */
  job = scope.launch(){
    binding.progress.startJobOrCancel(job) {
      binding.jobbutton.setText("StartJob #1")
    }
  }

Update (2020-11-17):

On the onCreate function inside the activity, remove the duplicated call to setContentView:

  ...
  setContentView(R.layout.activity_job) /* remove this if you're using view binding */
  binding = ActivityJobBinding.inflate(layoutInflater)
  setContentView(binding.root)
user_46084640

You should remove this line:

setContentView(R.layout.activity_job)

and in case of not using ViewBinding, you can use Kotlin Android Extensions by adding this plugin in Gradle :

 apply plugin: 'kotlin-android-extensions'

and just call view by its id! for example for TextView with this line of code:

 android:id="@+id/welcomeMessage"

you can easily call :

welcomeMessage.text = "Hello Kotlin!"
user_83693620

1.First thing's first, remove the OnCreate method its redundant and unnecessary:

setContentView(R.layout.activity_job)

2.You can decide to go back to the initial Kotlin method of calling views in the activity by their respective ID by adding this line (ps: this is the updated way of adding plugins in the new kotlin version 1.4.0:

plugins {
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

using this method, it is possible to do it the original way but slight warning,, you may be susceptible to calling null operations.

user_121233140
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