Why are the brush size options not appearing when using Dialogs in Kotlin Android Studio?

When i type brushDialog.ib_small_brush the option for the small brush should appear but it is not working. I tried rebuilding and cleaning the project but it still won't work.

an option of ib_large_brush, ib_medium_brush, and ib_small_brush should appear but it doesn't.

Main activity function:

private fun showBrushSizeChooserDialog(){
        val brushDialog = Dialog(this)
        brushDialog.setContentView(R.layout.dialogbrushsize)
        brushDialog.setTitle("Brush size: ")
        val smallBtn = brushDialog
    }

dialogbrushsize.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <ImageButton
        android:id="@+id/ib_small_brush"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="@string/small_brush"
        android:src="@drawable/small"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/ib_medium_brush"/>
    <ImageButton
        android:id="@+id/ib_medium_brush"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="@string/medium_brush"
        android:src="@drawable/medium"
        app:layout_constraintTop_toBottomOf="@id/ib_small_brush"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@+id/ib_large_brush"/>
    <ImageButton
        android:id="@+id/ib_large_brush"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:contentDescription="@string/large_brush"
        android:src="@drawable/large"
        app:layout_constraintTop_toBottomOf="@id/ib_medium_brush"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>




</androidx.constraintlayout.widget.ConstraintLayout>```



</details>


# 答案1
**得分**: 0

这是因为 `Dialog` 不知道你的自定义布局以及它包含的小部件。

尝试像这样：
```kotlin
private fun showBrushSizeChooserDialog(){
  val brushDialog = Dialog(this)
  brushDialog.setContentView(R.layout.dialogbrushsize)
  brushDialog.setTitle("画笔大小：")

  val smallBtn = brushDialog.findViewById<ImageButton>(R.id.ib_small_brush)
  val mediumBtn = brushDialog.findViewById<ImageButton>(R.id.ib_medium_brush)
  val largeBtn = brushDialog.findViewById<ImageButton>(R.id.ib_large_brush)
}

private fun showBrushSizeChooserDialog(){
  val brushDialog = Dialog(this)
  brushDialog.setContentView(R.layout.dialogbrushsize)
  brushDialog.setTitle("Brush size: ")

  val smallBtn = brushDialog.findViewById<ImageButton>(R.id.ib_small_brush)
  val mediumBtn = brushDialog.findViewById<ImageButton>(R.id.ib_medium_brush)
  val largeBtn = brushDialog.findViewById<ImageButton>(R.id.ib_large_brush)
}