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Bonjour,

J'ai fais une application de lecteur multimédia en suivant des tutos, mais impossible de la lancer en simulation sans qu'elle crash directement au lancement.
Eclipse m'indique aucune erreur dans le code. J'ai essayé de voir d'où venait mon erreur via le logcat, mais sans succès.
Pourriez vous m'aidez, svp ?

XML

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<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
   android:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   tools:context=".MainActivity" >
 
   <ImageButton
      android:id="@+id/imageButton3"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:layout_alignParentLeft="true"
      android:layout_marginBottom="14dp"
      android:onClick="forward"
      android:src="@android:drawable/ic_media_ff" />
 
   <ImageButton
      android:id="@+id/imageButton4"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentRight="true"
      android:layout_alignTop="@+id/imageButton2"
      android:layout_marginLeft="22dp"
      android:layout_toRightOf="@+id/imageButton2"
      android:onClick="rewind"
      android:src="@android:drawable/ic_media_rew" />
 
   <ImageButton
      android:id="@+id/imageButton2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignTop="@+id/imageButton1"
      android:layout_marginLeft="14dp"
      android:layout_toRightOf="@+id/imageButton1"
      android:onClick="pause"
      android:src="@android:drawable/ic_media_pause" />
 
   <ImageButton
      android:id="@+id/imageButton1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignTop="@+id/imageButton3"
      android:layout_marginLeft="24dp"
      android:layout_toRightOf="@+id/imageButton3"
      android:onClick="play"
      android:src="@android:drawable/ic_media_play" />
 
   <SeekBar
      android:id="@+id/seekBar1"
      android:layout_width="match_parent"
      android:layout_height="wrap_content" 
      android:layout_above="@+id/imageButton3"
      android:layout_toLeftOf="@+id/textView2"
      android:layout_toRightOf="@+id/textView1" />
 
   <TextView
      android:id="@+id/textView1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignRight="@+id/imageButton3"
      android:layout_alignTop="@+id/seekBar1"
      android:text="inital_Time"
      android:textAppearance="?android:attr/textAppearanceSmall" />
 
   <TextView
      android:id="@+id/textView2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/imageButton4"
      android:layout_alignTop="@+id/seekBar1"
      android:text="inital_Time"
      android:textAppearance="?android:attr/textAppearanceSmall" />
 
   <TextView
      android:id="@+id/textView3"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignLeft="@+id/imageButton3"
      android:text="@string/hello_world"
      android:textAppearance="?android:attr/textAppearanceMedium" />
 
   <ImageView
      android:id="@+id/imageView1"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_alignParentBottom="true"
      android:layout_alignParentLeft="true"
      android:layout_below="@+id/textView3"
      android:src="@drawable/ic_launcher" />
 
   <TextView
      android:id="@+id/textView4"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignBaseline="@+id/textView3"
      android:layout_alignBottom="@+id/textView3"
      android:layout_toRightOf="@+id/imageButton1"
      android:text="TextView" />
 
</RelativeLayout>

Le java

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package com.example.appli6;
 
import java.util.concurrent.TimeUnit;
 
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;
 
public class MainActivity extends Activity {
 
   public TextView songName,startTimeField,endTimeField;
   private MediaPlayer mediaPlayer;
   private double startTime = 0;
   private double finalTime = 0;
   private Handler myHandler = new Handler();;
   private int forwardTime = 5000; 
   private int backwardTime = 5000;
   private SeekBar seekbar;
   private ImageButton playButton,pauseButton;
   public static int oneTimeOnly = 0;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      songName = (TextView)findViewById(R.id.textView4);
      startTimeField =(TextView)findViewById(R.id.textView1);
      endTimeField =(TextView)findViewById(R.id.textView2);
      seekbar = (SeekBar)findViewById(R.id.seekBar1);
      playButton = (ImageButton)findViewById(R.id.imageButton1);
      pauseButton = (ImageButton)findViewById(R.id.imageButton2);
      songName.setText("song.mp3");
      mediaPlayer = MediaPlayer.create(this, R.raw.song);
      seekbar.setClickable(false);
      pauseButton.setEnabled(false);
 
   }
 
   public void play(View view){
   Toast.makeText(getApplicationContext(), "Playing sound", 
   Toast.LENGTH_SHORT).show();
      mediaPlayer.start();
      finalTime = mediaPlayer.getDuration();
      startTime = mediaPlayer.getCurrentPosition();
      if(oneTimeOnly == 0){
         seekbar.setMax((int) finalTime);
         oneTimeOnly = 1;
      } 
 
      endTimeField.setText(String.format("%d min, %d sec", 
         TimeUnit.MILLISECONDS.toMinutes((long) finalTime),
         TimeUnit.MILLISECONDS.toSeconds((long) finalTime) - 
         TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.
         toMinutes((long) finalTime)))
      );
      startTimeField.setText(String.format("%d min, %d sec", 
         TimeUnit.MILLISECONDS.toMinutes((long) startTime),
         TimeUnit.MILLISECONDS.toSeconds((long) startTime) - 
         TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.
         toMinutes((long) startTime)))
      );
      seekbar.setProgress((int)startTime);
      myHandler.postDelayed(UpdateSongTime,100);
      pauseButton.setEnabled(true);
      playButton.setEnabled(false);
   }
 
   private Runnable UpdateSongTime = new Runnable() {
      public void run() {
         startTime = mediaPlayer.getCurrentPosition();
         startTimeField.setText(String.format("%d min, %d sec", 
            TimeUnit.MILLISECONDS.toMinutes((long) startTime),
            TimeUnit.MILLISECONDS.toSeconds((long) startTime) - 
            TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.
            toMinutes((long) startTime)))
         );
         seekbar.setProgress((int)startTime);
         myHandler.postDelayed(this, 100);
      }
   };
   public void pause(View view){
      Toast.makeText(getApplicationContext(), "Pausing sound", 
      Toast.LENGTH_SHORT).show();
 
      mediaPlayer.pause();
      pauseButton.setEnabled(false);
      playButton.setEnabled(true);
   }	
   public void forward(View view){
      int temp = (int)startTime;
      if((temp+forwardTime)<=finalTime){
         startTime = startTime + forwardTime;
         mediaPlayer.seekTo((int) startTime);
      }
      else{
         Toast.makeText(getApplicationContext(), 
         "Cannot jump forward 5 seconds", 
         Toast.LENGTH_SHORT).show();
      }
 
   }
   public void rewind(View view){
      int temp = (int)startTime;
      if((temp-backwardTime)>0){
         startTime = startTime - backwardTime;
         mediaPlayer.seekTo((int) startTime);
      }
      else{
         Toast.makeText(getApplicationContext(), 
         "Cannot jump backward 5 seconds",
         Toast.LENGTH_SHORT).show();
      }
 
   }
 
   @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;
   }
 
 }

Et le logcat

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05-21 03:40:29.460: D/AndroidRuntime(1125): Shutting down VM
05-21 03:40:29.460: W/dalvikvm(1125): threadid=1: thread exiting with uncaught exception (group=0xb3a65ba8)
05-21 03:40:29.530: E/AndroidRuntime(1125): FATAL EXCEPTION: main
05-21 03:40:29.530: E/AndroidRuntime(1125): Process: com.example.appli6, PID: 1125
05-21 03:40:29.530: E/AndroidRuntime(1125): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.appli6/com.example.appli6.MainActivity}: java.lang.NullPointerException
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.os.Handler.dispatchMessage(Handler.java:102)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.os.Looper.loop(Looper.java:136)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread.main(ActivityThread.java:5017)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at java.lang.reflect.Method.invokeNative(Native Method)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at java.lang.reflect.Method.invoke(Method.java:515)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at dalvik.system.NativeStart.main(Native Method)
05-21 03:40:29.530: E/AndroidRuntime(1125): Caused by: java.lang.NullPointerException
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at com.example.appli6.MainActivity.onCreate(MainActivity.java:40)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.Activity.performCreate(Activity.java:5231)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
05-21 03:40:29.530: E/AndroidRuntime(1125): 	... 11 more
05-21 03:40:39.200: I/Process(1125): Sending signal. PID: 1125 SIG: 9

Merci