ボタンをタッチしたときにMediaPlayerを使用してMp3ファイルを再生する方法

Question

私はこの曲を再生しようとするたびに以下のエラーが表示されます。アクティビティはアプリのクラッシュと私はちょうどなぜこれが起こって、どのように問題を解決できるか知りたい。

エラー：

E/MediaPlayer: error (1, -2147483648) 
D/MediaPlayer: create failed: 
       java.io.IOException: Prepare failed.: status=0x1 
        at android.media.MediaPlayer._prepare(Native Method) 
        at android.media.MediaPlayer.prepare(MediaPlayer.java:1158) 
        at android.media.MediaPlayer.create(MediaPlayer.java:944) 
        at android.media.MediaPlayer.create(MediaPlayer.java:915) 
        at com.example.android.phaseup.AviationSongActivity.onCreate(AviationSongActivity.java:19) 
        at android.app.Activity.performCreate(Activity.java:6251) 
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
        at android.app.ActivityThread.-wrap11(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5422) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
D/AndroidRuntime: Shutting down VM 
E/AndroidRuntime: FATAL EXCEPTION: main 
        Process: com.example.android.phaseup, PID: 1644 
        java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.start()' on a null object reference 
         at com.example.android.phaseup.AviationSongActivity$1.onClick(AviationSongActivity.java:36) 
         at android.view.View.performClick(View.java:5204) 
         at android.view.View$PerformClick.run(View.java:21155) 
         at android.os.Handler.handleCallback(Handler.java:739) 
         at android.os.Handler.dispatchMessage(Handler.java:95) 
         at android.os.Looper.loop(Looper.java:148) 
         at android.app.ActivityThread.main(ActivityThread.java:5422) 
         at java.lang.reflect.Method.invoke(Native Method) 
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Application terminated. 

コードMainActivity.java：

package com.example.android.phaseup; 

import android.content.Intent; 
import android.net.Uri; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.view.View; 
import android.widget.TextView; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     //Call BlueBook Activity 
     TextView blueBook = (TextView) findViewById(R.id.blue_book); 

     //Set a click listener in that View 
     blueBook.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent blueBookIntent = new Intent(MainActivity.this, BlueBookActivity.class); 
       startActivity(blueBookIntent); 
      } 
     }); 

     //Call Aviation Song Activity 
     TextView aviationSong = (TextView) findViewById(R.id.aviation_songs); 

     //Set a click listener in that View 
     aviationSong.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent aviationIntent = new Intent(MainActivity.this, AviationSongActivity.class); 
       startActivity(aviationIntent); 
      } 
     }); 

     //Call Soldier's Creed Activity 
     TextView soldierCreed = (TextView) findViewById(R.id.soldier_creed); 

     //Set a click listener in that View 
     soldierCreed.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent soldierCreedIntent = new Intent(MainActivity.this, SoldierCreedActivity.class); 
       startActivity(soldierCreedIntent); 
      } 
     }); 

     //Call Room Inspection Activity 
     TextView roomInspection = (TextView) findViewById(R.id.room_inspection); 

     //Set a click listener in that View 
     roomInspection.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent roomInspectionIntent = new Intent(MainActivity.this, RoomInspectionActivity.class); 
       startActivity(roomInspectionIntent); 
      } 
     }); 

     //Call Wall Locker Inspection Activity 
     TextView wallLocker = (TextView) findViewById(R.id.wall_Locker_inspection); 

     //Set a click listener in that View 
     wallLocker.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent wallLockerIntent = new Intent(MainActivity.this, WallLockerActivity.class); 
       startActivity(wallLockerIntent); 
      } 
     }); 

     //Call ASU Inspection Activity 
     TextView asuInspection = (TextView) findViewById(R.id.asu_inspection); 

     //Set a click listener in that View 
     asuInspection.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent asuIntent = new Intent(MainActivity.this, ASUActivity.class); 
       startActivity(asuIntent); 
      } 
     }); 

     //Feedback button. 
     TextView sendFeedBack = (TextView) findViewById(R.id.send_feedback); 
     sendFeedBack.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent sendFeedbackIntent = new Intent(Intent.ACTION_SENDTO); 
       sendFeedbackIntent.setData(Uri.parse("mailto: algenisromero@gmail.com")); 
       sendFeedbackIntent.putExtra(Intent.EXTRA_SUBJECT, "Phase UP Support."); 
       if (sendFeedbackIntent.resolveActivity(getPackageManager()) != null) { 
        startActivity(sendFeedbackIntent); 
       } 
      } 
     }); 

    } 
} 

コードAviationSongActivity.java：

package com.example.android.phaseup; 

import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 

public class AviationSongActivity extends AppCompatActivity { 

    //Media Player variable. 
    MediaPlayer mMediaPlayer; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_aviation_song); 

     //Create and Upload the MP3 file. 
     mMediaPlayer = MediaPlayer.create(this, R.raw.aviationsong); 


     //The aviation song text show in the screen. 
     TextView textViewAviation = (TextView) findViewById(R.id.textview_aviation); 
     textViewAviation.setText("High above the best, high above the best \n\n" + 
       "We are Army Aviation USA, \n\n" + 
       "proud and strong We meet the test \n\n" + 
       "Skies filled with thunder \n\n" + 
       "Wearing silver wings upon our chest \n\n" + 
       "We meet the needs of Ground Command \n\n" + 
       "As we aid the Nation's quest \n\n" + 
       "Army Aviation, flying high above the best!"); 

     //Listener to play sound when user touched. 
     Button playButton = (Button) findViewById(R.id.play_sound); 

     playButton.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
      mMediaPlayer.start(); 

      } 
     }); 
    } 
} 

コードactivity_aviation_song.xml

<?xml version="1.0" encoding="utf-8"?> 
<ScrollView 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"> 

    <LinearLayout 
     android:id="@+id/activity_aviation_song" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:orientation="vertical" 
     tools:context="com.example.android.phaseup.AviationSongActivity"> 

     <RelativeLayout 
      android:layout_width="match_parent" 
      android:layout_height="170dp" 
      android:background="@color/colorPrimaryDark"> 

      <Button 
       android:id="@+id/play_sound" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_centerInParent="true" 
       android:text="PLAY" 
       android:textSize="56sp" 
       android:textStyle="bold" 
       android:textColor="@android:color/white" 
       android:background="@null"/> 

     </RelativeLayout> 

     <TextView 
      android:id="@+id/textview_aviation" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_margin="32dp" 
      android:gravity="center" 
      android:textSize="18sp" /> 

    </LinearLayout> 
</ScrollView> 

あなたは私のgithubのアカウントにあなたの助けを PhaseUp App

おかげでアプリの完全なコードを見つけることができます！

Answer 1

更新your MP3 fileですので、空でも破損していません。

コードは大丈夫です。