Using Media Player to play mp3 files. Adding SeekBar

1. International Islamic University H-10, Islamabad, Pakistan
Mobile Applications Development
Week 09
Using MediaPlayer
in Android
Engr. Rashid Farid Chishti
http://youtube.com/rfchishti
http://sites.google.com/site/chisht
i

2.  A class in Android used to play audio and video files.
 Supports multiple formats (MP3, AAC, OGG, WAV, etc.).
 Use cases:
 Playing background music.
 Playing sound effects in apps/games.
 Streaming audio from the internet.
 Basic MediaPlayer Workflow
 Create MediaPlayer instance
 Set data source (local file or URL)
 Prepare MediaPlayer
 Start playback
 Control playback (pause, stop, reset, release)
What is MediaPlayer ?

3. 1. Adding mp3 File

4. <?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:id="@+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:gravity="center"
tools:context=".MainActivity">
<Button
android:id="@+id/playButton"
android:text="▶ Play"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
1. Playing mp3 File from raw (activity_main.xml) (1/2)

5. <Button
android:id="@+id/pauseButton"
android:text=" Pause"
⏸
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"/>
</LinearLayout>
1. Playing mp3 File from raw (activity_main.xml) (2/2)

6. package com.example.myfirstapp
import android.widget.Button
import android.media.MediaPlayer
import android.os.Bundle
import androidx.activity.enableEdgeToEdge
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
class MainActivity : AppCompatActivity() {
private var mediaPlayer: MediaPlayer? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState); enableEdgeToEdge()
setContentView(R.layout.activity_main)
ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets -
>
val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
v.setPadding(systemBars.left, systemBars.top, systemBars.right,
systemBars.bottom)
insets
1. Playing mp3 File from raw (MainActivity.kt) (1/2)

7. val playButton: Button = findViewById(R.id.playButton)
val pauseButton: Button = findViewById(R.id.pauseButton)
mediaPlayer = MediaPlayer.create(this, R.raw.s_112)
playButton.setOnClickListener {
mediaPlayer?.start()
}
pauseButton.setOnClickListener {
if (mediaPlayer?.isPlaying == true) {
mediaPlayer?.pause()
}
}
}
override fun onDestroy() {
super.onDestroy(); mediaPlayer?.release(); mediaPlayer = null
}
}
1. Playing mp3 File from raw (MainActivity.kt) (2/2)

8. <?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:id="@+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
tools:context=".MainActivity">
<SeekBar
android:id="@+id/seek_bar"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#FF00FF"/>
2. Adding SeekBar (activity_main.xml) (1/2)

9. <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center">
<Button
android:id="@+id/playButton"
android:text="▶ Play"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Button
android:id="@+id/pauseButton"
android:text=" Pause"
⏸
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"/>
</LinearLayout>
</LinearLayout>
2. Adding SeekBar (activity_main.xml) (2/2)

10. package com.example.myfirstapp
import android.widget.Button
import android.media.MediaPlayer
import android.os.Bundle
import android.widget.SeekBar
import androidx.activity.enableEdgeToEdge
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.cancel
import kotlinx.coroutines.cancelChildren
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
class MainActivity : AppCompatActivity() {
var currentDuration:Int = 0
2. Adding SeekBar (MainActivity.kt) (1/4)

11. private var mediaPlayer: MediaPlayer? = null
lateinit var seek_bar: SeekBar
// This tells coroutines in this scope to run on the Main (UI) thread by
default.
// In Android, you must update UI elements (like SeekBar, TextView,
Button, etc.)
// only from the main thread
var myCoroutineScope = CoroutineScope(Dispatchers.Main)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState); enableEdgeToEdge()
setContentView(R.layout.activity_main)
ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets -
>
val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
v.setPadding(systemBars.left, systemBars.top, systemBars.right,
systemBars.bottom)
insets
}
seek_bar = findViewById(R.id.seek_bar)
2. Adding SeekBar (MainActivity.kt) (2/4)

12. seek_bar.max = mediaPlayer!!.duration
playButton.setOnClickListener {
mediaPlayer?.start()
myCoroutineScope.coroutineContext.cancelChildren()
// old jobs stopped, but you can still do:
myCoroutineScope.launch(Dispatchers.Main) {
while (true) {
if (mediaPlayer != null) {
currentDuration = mediaPlayer!!.currentPosition
seek_bar.setProgress(currentDuration)
delay(1000)
}
}
}
}
2. Adding SeekBar (MainActivity.kt) (3/4)

13. pauseButton.setOnClickListener {
if (mediaPlayer?.isPlaying == true) {
mediaPlayer?.pause()
}
}
}
override fun onDestroy() {
super.onDestroy();
// Cancels the entire scope, including all child coroutines.
myCoroutineScope.cancel()
// Releases the MediaPlayer resources.
mediaPlayer?.release(); mediaPlayer = null
}
override fun onPause() {
super.onPause()
if (mediaPlayer?.isPlaying == true) {
mediaPlayer?.pause()
} } }
2. Adding SeekBar (MainActivity.kt) (4/4)

14.  An Activity in Android is basically a single
screen of your app (like MainActivity).
 The Activity Lifecycle is the set of states an
Activity goes through
 from when it’s first created until it’s
destroyed.
 Android provides lifecycle callback
methods so you can run code when
these state changes happen.
3. Activity Life Cycle

15.  onCreate()
 Called once when the activity is created. Used for initialization (UI setup,
listeners, variables).
 onStart()
 Called when the activity becomes visible to the user but not yet interactive.
 onResume()
 Called when the activity is visible and interactive (user can see and
interact).
 onPause()
 Called when the activity is partially hidden (e.g., another activity appears on
top). Activity is still alive but not in the foreground.
3. Key Lifecycles Methods

16.  onStop()
 Called when the activity is no longer visible to the user.
 onRestart()
 Called before onStart() when the activity is being restarted after being
stopped
 onDestroy()
 Called before the activity is destroyed (when the app is closed or system
kills it).
 The lifecycle makes sure your app behaves properly when users
switch between apps, rotate the screen, or lock/unlock the phone.
3. Key Lifecycle Methods

17.  MediaPlayer holds system resources (audio, video decoders).
 Not releasing it can cause your app (or others) to fail to play audio.
 Call mediaPlayer?.release() when the Activity/Fragment is destroyed.
 Reuse a single MediaPlayer object instead of creating new ones unnecessarily.
 If you need to play a new file, call: mediaPlayer?.reset();
mediaPlayer?.setDataSource("new_file_path"); mediaPlayer?.prepare()
 Handle Activity Lifecycle
 onPause() → pause playback if user leaves screen.
 onResume() → resume if appropriate.
 onStop() → release heavy resources if app is not visible
 For streaming, playlists, buffering, or advanced controls, use ExoPlayer
Best Practices