【Kotlin/Android】BottomSheetBehaviorの使い方！下部から表示するモーダルビュー

build.gradle(Module：App)
dependencies {
  implementation 'com.google.android.material:material:1.5.0'
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    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="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    
</androidx.coordinatorlayout.widget.CoordinatorLayout>

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    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="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:id="@+id/bottom_sheet_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/black"
        android:orientation="vertical"
        app:behavior_peekHeight="300dp"
        app:behavior_hideable="true"
        app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">
        
        <Space
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="0.01" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@color/white"
            android:text="ボトムシート。"/>

        <Space
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="0.1" />

    </LinearLayout>
    
</androidx.coordinatorlayout.widget.CoordinatorLayout>

app:behavior_peekHeight="300dp"

app:behavior_hideable="true"

val bottomSheetLayout: LinearLayout = findViewById(R.id.bottom_sheet_layout)
val behavior = BottomSheetBehavior.from(bottomSheetLayout)

behavior.peekHeight = 300
behavior.isHideable = true

val bottomSheetLayout: LinearLayout = findViewById(R.id.bottom_sheet_layout)
val behavior = BottomSheetBehavior.from(bottomSheetLayout)

// 最初は非表示に設定する
behavior.state = BottomSheetBehavior.STATE_HIDDEN

openButton.setOnClickListener {
    behavior.state = BottomSheetBehavior.STATE_COLLAPSED
}

behavior.addBottomSheetCallback(
    object: BottomSheetBehavior.BottomSheetCallback() {
        override fun onSlide(bottomSheet: View, slideOffset: Float) {
            Log.d("BottomSheet", "スライド中")
        }

        override fun onStateChanged(bottomSheet: View, newState: Int) {
            // 状態変化を通知
            Log.d("BottomSheet", "状態変化：$newState")
        }
    }
)