We Keep Coding

How do I avoid a NullPointerException when stopping and starting a Clip in Java?

I'm making a game in Java and I want a theme song to play in the background, but every time the user presses minus the volume decreases. No matter what I try, I can't do this from another method besides the one where I initialized the Clip because the cli.
This is the code for my GameAudio class:
public class GameAudio {
private static float volume = -20.0f;
private Clip clip;
public GameAudio(String audioLocation) {
try {
File filePath = new File(audioLocation);
if (filePath.exists()) {
AudioInputStream audioInput = AudioSystem.getAudioInputStream(filePath);
Clip clip = AudioSystem.getClip();
clip.open(audioInput);
FloatControl gainControl = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);
gainControl.setValue(getVolume());
clip.loop(Clip.LOOP_CONTINUOUSLY);
clip.start();
} else {
System.out.println("Incorrect audio file path!");
}
} catch (Exception e) {
e.printStackTrace();
}
}
public float getVolume() {
return volume;
}
public void setVolume(float volume) {
GameAudio.volume = volume;
}
public void stopSound() {
clip.stop();
clip.close();
}
}
In my Player class I put:
private String musicPath = "maintheme.wav";
GameAudio gameAudio = new GameAudio(musicPath);
and then further down
if (input.minus.isPressed()) {
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
gameAudio.stopSound();
if (gameAudio.getVolume() <= -80.0f) {
gameAudio.setVolume(-70.0f);
}
gameAudio.setVolume(gameAudio.getVolume() - 10.0f);
System.out.println("Volume: " + gameAudio.getVolume());
}
When in debug mode the null pointer exception seems to come from gameAudio.stopSound() calling clip.stop(); and clip.close();
How can I avoid this?

Your problem is on this line:
Clip clip = AudioSystem.getClip();
This is creating a local variable, and not setting the clip to the member variable you are using below.
Instead, try:
clip = AudioSystem.getClip();

How I can check when music has ended

I have a JFrame with 2 buttons: Turn On and Turn Off
My problem is when a song has ended, I can't check that it ended and to play it again
How can I check it? Thank you so much
Below is the way that I play sound on Swing
class MP3 {
private Player player;
private String filename;
public MP3(String filename) {
this.filename = filename;
}
public void stop() {
if (player != null)
player.close();
}
public void play() {
try {
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(filename));
player = new Player(bis);
} catch (FileNotFoundException | JavaLayerException ex) {
System.out.println(ex);
}
new Thread(new Runnable() {
#Override
public void run() {
try {
player.play();
} catch (Exception ex) {
System.out.println(ex);
}
}
}).start();
}
}
And Event when I click buttons
private void btnPlayActionPerformed(java.awt.event.ActionEvent evt) {
sound = new MP3("src/Sound/02 - Cold Pizza.mp3");
sound.play();
btnPlay.setVisible(false);
btnStop.setVisible(true);
}
private void btnStopActionPerformed(java.awt.event.ActionEvent evt) {
sound.stop();
btnStop.setVisible(false);
btnPlay.setVisible(true);
}
sound is a instance of MP3 class in main class

I did it this way. I made the mp3 file a wav file. Then I made two objects
AudioInputStream songReader;
Clip song;
try{
songReader =
AudioSystem.getAudioInputStream(
getClass().getResource("wally.wav"));
song = AudioSystem.getClip();
song.open(songReader);
}catch (Exception e){
System.out.println("won't work");
}
try{
song.stop();
song.setFramePosition(0);
}catch(Exception e){
System.out.println("Error playing your music");
}
try{
song.start();
song.loop(song.LOOP_CONTINUOUSLY);
}catch(Exception e){
System.out.println("Won't work");
}
This makes it play infinitely, but if you need you can stop it at any point with song.stop(). Hopefully, that will work for you.

Java music not working

I made a java program and wanted a background music so I used this function
public static void playSound(final String url) {
new Thread(new Runnable() {
public void run() {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem
.getAudioInputStream(getClass().getResourceAsStream("/" + url));
clip.open(inputStream);
clip.start();
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
}).start();
}
only problem is when I try to run the 27 minute wav file, it speeds it up really fast

LineUnavailableException while playing sound in java

I have this slightly altered a sound manager from another question How can I play sound in Java?. Here it is:
public static synchronized void playSound(final String url)
{
new Thread(new Runnable()
{
public void run()
{
try
{
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(new File("sound/" + url));
clip.open(inputStream);
clip.start();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}).start();
}
Whenever I call this method I get a javax.sound.sampled.LineUnavailableException in the clip.open(inputStream);. What can I do to repair it? Why does it not work?

What is wrong with my code so it can't play wav file?

I'm trying to use the code which available on: How can I play sound in Java?
but I can't post question there since this is a new account and only have 1 reputation.
original code:
public static synchronized void playSound(final String url) {
new Thread(new Runnable() { // the wrapper thread is unnecessary, unless it blocks on the Clip finishing, see comments
public void run() {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(Main.class.getResourceAsStream("/path/to/sounds/" + url));
clip.open(inputStream);
clip.start();
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
}).start();
}
and this is my code:
package sound_test;
import javax.sound.sampled.*;
public class Main {
public static synchronized void playSound(final String url) {
new Thread(new Runnable() {
public void run() {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(Main.class.getResourceAsStream("/path/to/sounds/" + url));
clip.open(inputStream);
clip.start();
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
}).start();
}
public static void main(String[] args) {
// TODO code application logic here
playSound("C:\\warning_test.wav");
}
}
When I run the code i receive "null" as the output and no sound came out.
I've checked the file name and the path, it's correct.
screenshots:
http://puu.sh/pkYo
http://puu.sh/pkZl
Thank you in advance.

you could do
AudioInputStream inputStream=AudioSystem.getAudioInputStream(new File(url));
also add a delay after click.start(); i.e Thread.Sleep(4000);
or if you want to make sure it plays the entire audio sample you could use a simple snippet such as
import javax.sound.sampled.*;
import java.io.File;
public class Main implements LineListener {
private boolean done = false;
public void update(LineEvent event) {
if(event.getType() == LineEvent.Type.STOP || event.getType() == LineEvent.Type.CLOSE) {
done = true;
}
}
public void waitonfinish() throws InterruptedException {
while(!done) {
Thread.sleep(1000);
}
}
public static void playSound(final String url) {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(new File(url));
Main control = new Main();
clip.addLineListener(control);
clip.open(inputStream);
clip.start();
control.waitonfinish();
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
public static void main(String[] args) {
// TODO code application logic here
playSound("C:\\warning_test.wav");
}
}
`

You copied the code entirely without noticing the in the original, it points to
path/to/sounds
since you give it the full path, u should replace it with just url:
AudioInputStream inputStream = AudioSystem.getAudioInputStream(Main.class.getResourceAsStream(url));
EDIT:
I tried here and got null as well.
I changed it to create the audioInput from a file:
import java.io.File;
import javax.sound.sampled.*;
public class Main {
public static synchronized void playSound(final File file) {
new Thread(new Runnable() {
public void run() {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(file);
clip.open(inputStream);
clip.start();
} catch (Exception e) {
e.printStackTrace();
System.err.println(e.getMessage());
}
}
}).start();
}
public static void main(String[] args) {
// TODO code application logic here
File file = new File("C:\\warning_test.wav");
playSound(file);
}