How to play audio files in Kotlin
Article directory
1 Download and place the audio file
We can download an audio file at will, for example alarm.mp3, it needs to be placed /res/raw/under the path.
2 activity_main.xml
Here, we add a button. When we press this button, the APP will play the specified music.
<Button
android:id="@+id/pushButton"
android:layout_width="150dp"
android:layout_height="150dp"
android:text="Press"
android:textColor="@color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.344" />
3 MainActivity.kt
class MainActivity : AppCompatActivity() {
private var mediaPlayer: MediaPlayer? = null
@SuppressLint("ClickableViewAccessibility", "ResourceType")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
mediaPlayer = MediaPlayer.create(this, R.raw.alarm1)
mediaPlayer?.setOnPreparedListener{
println("READY TO GO")
}
pushButton.setOnTouchListener {
_, event ->
handleTouch(event)
true
}
}
// 按下按钮后，报警声音响起
private fun handleTouch(event: MotionEvent)
{
when (event.action) {
MotionEvent.ACTION_DOWN -> {
println("down")
mediaPlayer?.start()
}
MotionEvent.ACTION_UP -> {
println("up")
mediaPlayer?.pause()
mediaPlayer?.seekTo(0)
// 使用完MediaPlayer需要回收资源。
// MediaPlayer是很消耗系统资源的，所以在使用完MediaPlayer，不要等待系统自动回收，最好是主动回收资源。
if (mediaPlayer != null && mediaPlayer?.isPlaying == true) {
mediaPlayer?.stop()
mediaPlayer?.release()
mediaPlayer = null
}
}
else -> {
println("others")
}
}
}
}
The logic here is relatively straightforward, and there are a few points that need to be explained. First of all, we need to create a new MediaPlayer for playing custom music: MediaPlayer.create(this, R.raw.alarm1), here, the music is named alarm1.mp3and stored in res/raw/the folder. mediaPlayer?.setOnPreparedListenerDoesn't do anything here, what this function does is tell us when the audio is ready to play: Register a callback to be invoked when the media source is ready for playback.. When we press the button, handleTouchthe function is fired, or more precisely, handleTouchin the MotionEvent.ACTION_DOWN. mediaPlayer?.start()That is, an instruction to play music. handleTouchThe in is fired when we release the button MotionEvent.ACTION_UP. Finally, it should be noted that MediaPlayer consumes a lot of system resources, so after using MediaPlayer, do not wait for the system to automatically recycle, it is best to actively recycle resources: mediaPlayer?.stop(), mediaPlayer?.release().