Kotlin 대화상자(Dialog) : 기본 알림 대화상자(AlertDialog)
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      activity_main.xml
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="대화상자"
        android:background="@drawable/button" />
</LinearLayout>

------------------------------------------------------------------------------------
    botton.xml
-- res/drawable
-- New --> Drawable Resource File
-- File Name : button  , Root Element : shape
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<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:padding="10dp"
    android:shape="rectangle" >
    <solid android:color="#8EC7F4" />
    <stroke android:color="#ff0000ff" android:width="4dp" />
    <padding android:left="7dp" android:top="7dp"
        android:right="7dp" android:bottom="7dp" />
    <corners
        android:radius="30dp"
        android:bottomLeftRadius="30dp"
        android:bottomRightRadius="30dp"
        android:topLeftRadius="30dp"
        android:topRightRadius="30dp" />
</shape>

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

        var button1 = findViewById<Button>(R.id.button1)

        button1.setOnClickListener {
            var dlg = AlertDialog.Builder(this@MainActivity)
            dlg.setTitle("제목입니다")
            dlg.setMessage("이곳이 내용입니다")
            dlg.setIcon(R.mipmap.ic_launcher)
            dlg.show()
        }
    }
}

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    themes.xml
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<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Base.Theme.AlertDialogBase" parent="Theme.AppCompat.Light">
        <item name="colorPrimary">#FF9800</item>
        <item name="colorPrimaryDark">#FF5722</item>
    </style>

    <style name="Theme.AlertDialogBase" parent="Base.Theme.AlertDialogBase" />
</resources>