CODEWITHSUNDEEP
androidkotlin
Jordan Kellogg
Jordan Kellogg

Reputation: 15

Unresolved reference: activity_main

I'm trying to work on this example from a book. I keep receiving an "Unresolved reference: activity_main" error. I am fairly new to Kotlin and Android Studio. The code is show below.

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.MotionEvent
import android.view.View
import android.widget.TextView


import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        activity_main.setOnTouchListener {_, m: MotionEvent ->
            handleTouch(m)
            true
        }

    }

Could you help me as to why Android Studio is throwing this error? Am I missing an import?

Upvotes: 0

Views: 1229

Answers (2)

I am a Cat
I am a Cat

Reputation: 11

handleTouch is a function that you havent declared yet.

private fun handleTouch(m: MotionEvent)
    {
        val pointerCount = m.pointerCount
        for (i in 0 until pointerCount)
        {
            val x = m.getX(i)
            val y = m.getY(i)
            val id = m.getPointerId(i)
            val action = m.actionMasked
            val actionIndex = m.actionIndex
            var actionString: String
            when (action)
            {
                MotionEvent.ACTION_DOWN -> actionString = "DOWN"
                MotionEvent.ACTION_UP -> actionString = "UP"
                MotionEvent.ACTION_POINTER_DOWN -> actionString = "PNTR DOWN"
                MotionEvent.ACTION_POINTER_UP -> actionString = "PNTR UP"
                MotionEvent.ACTION_MOVE -> actionString = "MOVE"
                else -> actionString = ""
            }
            val touchStatus =
                "Action: $actionString Index: $actionIndex ID: $id X: $x Y: $y"
            if (id == 0)
                binding.textView1.text = touchStatus
            else
                binding.textView2.text = touchStatus
        }
    }

Upvotes: 0

Alexander Dadukin
Alexander Dadukin

Reputation: 564

Yeah, activity_main is your layout file and you can find it in res/layout folder inside of your project.

            activity_main.setOnTouchListener {_, m: MotionEvent ->
                handleTouch(m)
                true
            }

this line makes no sense if inside of your activity_main file you dont have view with id activity_main. So, if you want to add touch listener to your root view inside of layout, just open activity_main file and add android:id="@+id/root" to your top view definition. Also, change activity_main.setOnTouchListener to root.setOnTouchListener. Android Studio will help you with imports of synthetic field

Upvotes: 2

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