I am trying to make a drawing app but when I am setting the brush size seek and try to make a text view to show its size it is always returning null I tried multiple ways but it didn't succeed so please can any one help me fix the poblems in this code so the text shows the seekbar progress text

class MainActivity : AppCompatActivity() {
        private var ibBrush: ImageView? = null
        private var tvBrushSize: TextView? = null
        private var sbBrushSize: SeekBar?= null
    
        override fun onCreate(savedInstanceState: Bundle?) {
            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
            ibBrush = findViewById(R.id.ib_brush)
            ibBrush?.setOnClickListener{
                changeBrushSize()
            }
    
    
        }
        private fun changeBrushSize(){
            AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
            val brushDialog = Dialog(this)
            brushDialog.setContentView(R.layout.brush_size_dialog)
            tvBrushSize = findViewById(R.id.tv_brush_size)
            sbBrushSize = findViewById(R.id.sb_brush_size)
    
            tvBrushSize?.text = sbBrushSize?.progress.toString()
    
    
            brushDialog.show()
    
    
        }
    }

Why tvBrushSize is returning null while I am setting it to findViewById() to the correct id in xml

*here is the xml *

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:padding="10dp"
    android:orientation="vertical"

    >

    <TextView
        android:id="@ id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/brush_size"
        android:gravity="center"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@ id/linear"/>

    <LinearLayout
        android:layout_width="350dp"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:orientation="horizontal"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@ id/textView">

        <SeekBar
            android:id="@ id/sb_brush_size"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="10"
            android:max="30"
            />

        <TextView
            android:id="@ id/tv_brush_size"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="@string/_0" />
    </LinearLayout>
</LinearLayout>

CodePudding user response：

the dialog with your view is not yet existed, when you are trying to refer it with findViewById() You can inflate view first, then access it as follows

        val brushDialog = Dialog(this)
        val view = layoutInflater.inflate(R.layout.brush_size_dialog, null) 
        brushDialog.setContentView(view)
        tvBrushSize = view.findViewById(R.id.tv_brush_size)
        sbBrushSize = view.findViewById(R.id.sb_brush_size)
        tvBrushSize?.text = sbBrushSize?.progress.toString()
        brushDialog.show()

or call brushDialog.show() first and then access views with findViewById()

that also should work

CodePudding user response：

you need to bind views from dialog, so manage it like this;

  brushDialog.setContentView(R.layout.brush_size_dialog)
  val dialogView = layoutInflater.inflate(R.layout.brush_size_dialog, null) 
  brushDialog.setContentView(dialogView)
  tvBrushSize = dialogView.findViewById(R.id.tv_brush_size)

CodePudding user response：

You should inflate the dialog view first using LayoutInflater.inflate(layoutId) and then use view.findViewById(id) like this snippet:

   private fun changeBrushSize(){
        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
        val brushDialog = Dialog(this)
        val dialogView = LayoutInflater.inflate(R.layout.brush_size_dialog, null)
        brushDialog.setContentView(dialogView)
        tvBrushSize = dialogView.findViewById(R.id.tv_brush_size)
        sbBrushSize = dialogView.findViewById(R.id.sb_brush_size)

        tvBrushSize?.text = sbBrushSize?.progress.toString()


        brushDialog.show()


    }

CodePudding user response：

You should inflate the view first

val dialogView = LayoutInflater.inflate(R.layout.brush_size_dialog, null)
brushDialog.setContentView(dialogView)

then try to use

dialogView.findViewById(...)