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问题:

I have looked at various different websites looking for a solution for this problem in my code. It is a basic audio player with 3 buttons: play, pause and stop. Play and pause work ok and so does stop but once the audio has been stopped it refuses to start again, throwing an error:

E/MediaPlayer: stop called in state 0 E/MediaPlayer: error (-38, 0) E/MediaPlayer: Error (-38,0)

This is my MainActivity.java:

import android.app.Activity; import android.media.MediaPlayer; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.SeekBar;  import java.io.IOException;  public class MainActivity extends Activity implements MediaPlayer.OnPreparedListener {      static Button playButton;     static Button pauseButton;     static Button stopButton;     static SeekBar seekBar;     private static MediaPlayer player; static Handler handler; static Uri audio;  @Override protected void onCreate(Bundle savedInstanceState) {     player = MediaPlayer.create(this, R.raw.airbourne_runnin_wild);     Uri audio = Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.airbourne_runnin_wild);     try {         player.setDataSource(getAssets().openFd("raw/airbourne_runnin_wild.mp3").getFileDescriptor());     } catch (IOException e) {         e.printStackTrace();     }     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      playButton = (Button) findViewById(R.id.playButton);     pauseButton = (Button) findViewById(R.id.pauseButton);     stopButton = (Button) findViewById(R.id.stopButton);     seekBar = (SeekBar) findViewById(R.id.seekBar);      player.setOnPreparedListener(this);      handler = new Handler();      seekBar.setMax(player.getDuration());      playButton.setOnClickListener(new View.OnClickListener() {         public void onClick(View view) {             if (!player.isPlaying()) {                 try {                     player.setDataSource(getAssets().openFd("raw/airbourne_runnin_wild.mp3").getFileDescriptor());                 } catch (IOException e) {                     e.printStackTrace();                 }                 player.start();                 updateSeekBar();             }         }     });      pauseButton.setOnClickListener(new View.OnClickListener() {         public void onClick(View view) {             if (player.isPlaying()) {                 player.pause();             }         }     });      stopButton.setOnClickListener(new View.OnClickListener() {         public void onClick(View view) {             if (player.isPlaying()) {                 player.stop();                 seekBar.setProgress(0);                 seekBar.invalidate();                 try {                     player.setDataSource(getAssets().openFd("raw/airbourne_runnin_wild.mp3").getFileDescriptor());                 } catch (IOException e) {                     e.printStackTrace();                 }             }         }     });      seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {         @Override         public void onProgressChanged(SeekBar seekBar, int i, boolean b) {             if (b) {                 seekChanged(seekBar, i, b);             }         }          @Override         public void onStartTrackingTouch(SeekBar seekBar) {          }          @Override         public void onStopTrackingTouch(SeekBar seekBar) {          }     });      player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {         @Override         public void onCompletion(MediaPlayer mediaPlayer) {             player.stop();             seekBar.setProgress(0);             //player.prepareAsync();             seekBar.invalidate();         }     }); }   @Override public boolean onCreateOptionsMenu(Menu menu) {     // Inflate the menu; this adds items to the action bar if it is present.     getMenuInflater().inflate(R.menu.main, menu);     return true; }  @Override public void onPrepared(MediaPlayer mediaPlayer) {     playButton.setEnabled(true); }  public void seekChanged(SeekBar seekBar, int progress, boolean fromUser) {     player.seekTo(progress); }  public void updateSeekBar() {     seekBar.setProgress(player.getCurrentPosition());      if (player.isPlaying()) {         Runnable notification = new Runnable() {             public void run() {                 updateSeekBar();             }         };         handler.postDelayed(notification, 1500);     } } }

And activity_main.xml:

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">  <TableRow         android:layout_width="fill_parent"         android:layout_height="fill_parent">      <Button             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="Play"             android:id="@+id/playButton"             android:layout_gravity="center_horizontal|top"             android:longClickable="false"             android:layout_weight="1"             android:layout_column="8"             android:enabled="false"/> </TableRow>  <TableRow         android:layout_width="fill_parent"         android:layout_height="fill_parent">      <Button             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="Pause"             android:id="@+id/pauseButton"             android:layout_gravity="center_horizontal|top"             android:layout_weight="1"             android:layout_column="8"             android:layout_span="7"/> </TableRow>  <TableRow         android:layout_width="fill_parent"         android:layout_height="fill_parent">      <Button             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="Stop"             android:id="@+id/stopButton"             android:layout_column="8"             android:layout_span="24"             android:layout_weight="1"/> </TableRow>  <TableRow         android:layout_width="fill_parent"         android:layout_height="fill_parent"> </TableRow>  <TableRow         android:layout_width="fill_parent"         android:layout_height="fill_parent">      <SeekBar             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:id="@+id/seekBar"             android:layout_column="8"             android:layout_span="24"             android:layout_weight="1"/> </TableRow>

If anyone could help me resolve this error, it would be much appreciated. I have already searched round for solutions and tried multiple, but none seemed to work properly.

EDIT: I changed a little bit of the code:

My question is still about the error, and this is now my edited code:

import android.app.Activity; import android.media.MediaPlayer; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.SeekBar;  import java.io.IOException;  public class MainActivity extends Activity implements MediaPlayer.OnPreparedListener {  static Button playButton; static Button pauseButton; static Button stopButton; static SeekBar seekBar; private static MediaPlayer player; static Handler handler; static Uri audio; static boolean canMakeCall = false;  @Override protected void onCreate(Bundle savedInstanceState) {     player = MediaPlayer.create(this, R.raw.airbourne_runnin_wild);     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      playButton = (Button) findViewById(R.id.playButton);     pauseButton = (Button) findViewById(R.id.pauseButton);     stopButton = (Button) findViewById(R.id.stopButton);     seekBar = (SeekBar) findViewById(R.id.seekBar);      if (canMakeCall = true) {         player.setOnPreparedListener(this);          handler = new Handler();          seekBar.setMax(player.getDuration());          playButton.setOnClickListener(new View.OnClickListener() {             public void onClick(View view) {                 if (!player.isPlaying()) {                     player.start();                     updateSeekBar();                 }             }         });          pauseButton.setOnClickListener(new View.OnClickListener() {             public void onClick(View view) {                 if (player.isPlaying()) {                     player.pause();                 }             }         });          stopButton.setOnClickListener(new View.OnClickListener() {             public void onClick(View view) {                 if (player.isPlaying()) {                     player.stop();                     seekBar.setProgress(0);                     seekBar.invalidate();                     try {                         player.prepare();                     } catch (IOException e) {                         e.printStackTrace();                     }                 }             }         });          seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {             @Override             public void onProgressChanged(SeekBar seekBar, int i, boolean b) {                 if (b) {                     seekChanged(seekBar, i, b);                 }             }              @Override             public void onStartTrackingTouch(SeekBar seekBar) {              }              @Override             public void onStopTrackingTouch(SeekBar seekBar) {              }         });          player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {             @Override             public void onCompletion(MediaPlayer mediaPlayer) {                 mediaPlayer.stop();                 //player.stop();                  seekBar.setProgress(0);                 //player.prepareAsync();                 seekBar.invalidate();             }         });     } }   @Override public boolean onCreateOptionsMenu(Menu menu) {     // Inflate the menu; this adds items to the action bar if it is present.     getMenuInflater().inflate(R.menu.main, menu);     return true; }  @Override public void onPrepared(MediaPlayer mediaPlayer) {     playButton.setEnabled(true);     canMakeCall = true; }  public void seekChanged(SeekBar seekBar, int progress, boolean fromUser) {     player.seekTo(progress); }  public void updateSeekBar() {     seekBar.setProgress(player.getCurrentPosition());      if (player.isPlaying()) {         Runnable notification = new Runnable() {             public void run() {                 updateSeekBar();             }         };         handler.postDelayed(notification, 1500);     } } }

I have tried getting the basics working without a seekbar too, just to make sure that isn't causing an error but it lies somewhere within the logic of the play/pause/stop code because it was producing the same error even with the seekbar code omitted.

回答1:

The problem is once you've stopped it, you setDataSource again. You have to then call prepare()

player.setDataSource(getAssets().openFd("raw/airbourne_runnin_wild.mp3").getFileDescriptor()); player.prepare();

Anytime you call setDataSource() on it you will need to prepare() it again. Think of it as loading the file, getting ready for playback.

By the way I notice you mix up calling MediaPlayer.create() and also call setDataSource() multiple times for the same file. There's no need to do this. Once the MediaPlayer is created and prepared (which calling .create() does for you), you can just call .stop(), .pause(), .play() on it, no need to reset it all the time.

回答2:

I fixed this problem by removing the player.stop() which was being called when the player finished the song because of player.setOnCompletionListener(). This has now resolved the problem and the player is working perfectly.

回答3:

I fixed this problem by `mediaPlayer.prepare(); My problem is about live radio streaming and I achieve this problem like below code:

if (!radioIsOpen) {                 try {                     mediaPlayer = new MediaPlayer();                     mediaPlayer                             .setDataSource(URL);                     mediaPlayer.prepare();                 } catch (Exception e) {                 }                  mediaPlayer.setOnPreparedListener(new OnPreparedListener() {                      public void onPrepared(MediaPlayer mp) {                         mediaPlayer.start();                     }                 });                 Toast.makeText(getBaseContext(), "Radio is opening...", 2).show();             } else {                 if (mediaPlayer.isPlaying()) {                     mediaPlayer.stop();                     mediaPlayer.release();                     Toast.makeText(getBaseContext(), "Radio is closing...", 2).show();                 }             }

文章来源: Android MediaPlayer Error (-38, 0) “stop called in state 0”

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