Kotlin 스레드(Thread) : 음악 듣기와 SeekBar를 이용한 Thread

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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:orientation="vertical"
    tools:context=".MainActivity">

    <Switch
        android:id="@+id/switch1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:text="음악듣기" />
    <SeekBar
        android:id="@+id/pbMP3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"/>
</LinearLayout>

------------------------------------------------------------------------------------
    MainActivity.kt
------------------------------------------------------------------------------------
class MainActivity : AppCompatActivity() {
    lateinit var mPlayer: MediaPlayer
    lateinit var pbMP3: SeekBar
    lateinit var switch1: Switch

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

        pbMP3 = findViewById<SeekBar>(R.id.pbMP3)

        switch1 = findViewById<Switch>(R.id.switch1)
        switch1.setOnClickListener {
            if (switch1.isChecked == true) {
                mPlayer = MediaPlayer.create(applicationContext, R.raw.song1)
                mPlayer.start()
                makeThread()
            } else {
                mPlayer.stop()
            }
        }

        pbMP3.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onStopTrackingTouch(seekBar: SeekBar) {}
            override fun onStartTrackingTouch(seekBar: SeekBar) {}
            override fun onProgressChanged(seekBar: SeekBar, progress: Int, fromUser: Boolean) {
                if (fromUser) {
                    mPlayer.seekTo(progress)
                }
            }
        })

    }

    fun makeThread() {
        object : Thread() {
            override fun run() {
                //            ۵    ̶
                while (mPlayer.isPlaying) {
                    pbMP3.max = mPlayer.duration //        ð    ִ
                    pbMP3.progress = mPlayer.currentPosition //        ġ
                    SystemClock.sleep(100)
                }
                pbMP3.progress = 0
            }
        }.start()
    }
}

------------------------------------------------------------------------------------
    themes.xml
------------------------------------------------------------------------------------
<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Base.Theme.ThreadMusicSeekBar" parent="Theme.AppCompat.Light">
        <item name="colorPrimary">#FFC107</item>
        <item name="colorPrimaryDark">#E91E63</item>
    </style>

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