Android StudioでSoundPoolを実行するには

Question

Androidスタジオでの作業は初めてです。私は学校の課題に取り組んでいますが、アプリケーションをクラッシュさせずにSoundPoolを動作させるのに問題があります。私が追加した音がなくてもアプリが動くことは知っていますが、この問題に近づく方法が非常に多いように私のエラーがどこにあるのかは不明です。

私はデバッグに取得していますエラーは次のとおりです。

のjava.lang.NullPointerException：「仮想メソッドを呼び出そうとint型 android.media.SoundPool.play（int型、float型、float型、int型、int型、float） 'on a nullオブジェクト参照

マイコードは以下のとおりです。 パブリッククラススネークアクティビティを拡張し、私は自分の仕事をするために誰かを捜しているわけではない

{

private SnakeView mSnakeView; 

private static String ICICLE_KEY = "snake-view"; 


/** 
* Called when Activity is first created. Turns off the title bar, sets up 
* the content views, and fires up the SnakeView. 
* 
*/ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    //set the layout 
    setContentView(R.layout.snake_layout); 



    mSnakeView = (SnakeView) findViewById(R.id.snake); 
    mSnakeView.setTextView((TextView) findViewById(R.id.text)); 

    if (savedInstanceState == null) { 
     // We were just launched -- set up a new game 
     mSnakeView.setMode(SnakeView.READY); 
    } else { 
     // We are being restored 
     Bundle map = savedInstanceState.getBundle(ICICLE_KEY); 
     if (map != null) { 
      mSnakeView.restoreState(map); 
     } else { 
      mSnakeView.setMode(SnakeView.PAUSE); 
     } 
    } 
} 

@Override 
protected void onPause() { 
    super.onPause(); 
    // Pause the game along with the activity 
    mSnakeView.setMode(SnakeView.PAUSE); 
} 

@Override 
public void onSaveInstanceState(Bundle outState) { 
    //Store the game state 
    outState.putBundle(ICICLE_KEY, mSnakeView.saveState()); 
} 

パブリッククラスSnakeViewはTileView {

private static final String TAG = "SnakeView"; 

private Context m_context; 

//Sound 
//initialize sound variables 
private SoundPool sounds; 
private int ulose = -1; 
private int apple = -1; 
private int moving = -1; 

/** 
* Current mode of application: READY to run, RUNNING, or you have already 
* lost. static final ints are used instead of an enum for performance 
* reasons. 
*/ 
private int mMode = READY; 
public static final int PAUSE = 0; 
public static final int READY = 1; 
public static final int RUNNING = 2; 
public static final int LOSE = 3; 

/** 
* Current direction the snake is headed. 
*/ 
private int mDirection = NORTH; 
private int mNextDirection = NORTH; 
private static final int NORTH = 1; 
private static final int SOUTH = 2; 
private static final int EAST = 3; 
private static final int WEST = 4; 

/** 
* Labels for the drawables that will be loaded into the TileView class 
*/ 
private static final int RED_STAR = 1; 
private static final int YELLOW_STAR = 2; 
private static final int GREEN_STAR = 3; 

/** 
* mScore: used to track the number of apples captured mMoveDelay: number of 
* milliseconds between snake movements. This will decrease as apples are 
* captured. 
*/ 
private long mScore = 0; 
private long mMoveDelay = 600; 
/** 
* mLastMove: tracks the absolute time when the snake last moved, and is used 
* to determine if a move should be made based on mMoveDelay. 
*/ 
private long mLastMove; 

/** 
* mStatusText: text shows to the user in some run states 
*/ 
private TextView mStatusText; 

/** 
* mSnakeTrail: a list of Coordinates that make up the snake's body 
* mAppleList: the secret location of the juicy apples the snake craves. 
*/ 
private ArrayList<Coordinate> mSnakeTrail = new ArrayList<Coordinate>(); 
private ArrayList<Coordinate> mAppleList = new ArrayList<Coordinate>(); 

/** 
* Everyone needs a little randomness in their life 
*/ 
private static final Random RNG = new Random(); 

/** 
* Create a simple handler that we can use to cause animation to happen. We 
* set ourselves as a target and we can use the sleep() 
* function to cause an update/invalidate to occur at a later date. 
*/ 
private RefreshHandler mRedrawHandler = new RefreshHandler(); 

class RefreshHandler extends Handler { 

    @Override 
    public void handleMessage(Message msg) { 
     SnakeView.this.update(); 
     SnakeView.this.invalidate(); 
    } 

    public void sleep(long delayMillis) { 
     this.removeMessages(0); 
     sendMessageDelayed(obtainMessage(0), delayMillis); 
    } 
}; 


/** 
* Constructs a SnakeView based on inflation from XML 
* 
* @param context 
* @param attrs 
*/ 
public SnakeView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    initSnakeView(); 

}

public SnakeView(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    initSnakeView(); 
} 

private void initSnakeView() { 
    setFocusable(true); 

    Resources r = this.getContext().getResources(); 

    resetTiles(4); 
    loadTile(RED_STAR, r.getDrawable(R.drawable.redstar)); 
    loadTile(YELLOW_STAR, r.getDrawable(R.drawable.yellowstar)); 
    loadTile(GREEN_STAR, r.getDrawable(R.drawable.greenstar)); 

} 


private void initNewGame() { 
    mSnakeTrail.clear(); 
    mAppleList.clear(); 

    // For now we're just going to load up a short default eastbound snake 
    // that's just turned north 


    mSnakeTrail.add(new Coordinate(7, 7)); 
    mSnakeTrail.add(new Coordinate(6, 7)); 
    mSnakeTrail.add(new Coordinate(5, 7)); 
    mSnakeTrail.add(new Coordinate(4, 7)); 
    mSnakeTrail.add(new Coordinate(3, 7)); 
    mSnakeTrail.add(new Coordinate(2, 7)); 
    mNextDirection = NORTH; 

    // Two apples to start with 
    addRandomApple(); 
    addRandomApple(); 

    mMoveDelay = 600; 
    mScore = 0; 
} 


/** 
* Given a ArrayList of coordinates, we need to flatten them into an array of 
* ints before we can stuff them into a map for flattening and storage. 
* 
* @param cvec : a ArrayList of Coordinate objects 
* @return : a simple array containing the x/y values of the coordinates 
* as [x1,y1,x2,y2,x3,y3...] 
*/ 
private int[] coordArrayListToArray(ArrayList<Coordinate> cvec) { 
    int count = cvec.size(); 
    int[] rawArray = new int[count * 2]; 
    for (int index = 0; index < count; index++) { 
     Coordinate c = cvec.get(index); 
     rawArray[2 * index] = c.x; 
     rawArray[2 * index + 1] = c.y; 
    } 
    return rawArray; 
} 

/** 
* Save game state so that the user does not lose anything 
* if the game process is killed while we are in the 
* background. 
* 
* @return a Bundle with this view's state 
*/ 
public Bundle saveState() { 
    Bundle map = new Bundle(); 

    map.putIntArray("mAppleList", coordArrayListToArray(mAppleList)); 
    map.putInt("mDirection", Integer.valueOf(mDirection)); 
    map.putInt("mNextDirection", Integer.valueOf(mNextDirection)); 
    map.putLong("mMoveDelay", Long.valueOf(mMoveDelay)); 
    map.putLong("mScore", Long.valueOf(mScore)); 
    map.putIntArray("mSnakeTrail", coordArrayListToArray(mSnakeTrail)); 

    return map; 
} 

/** 
* Given a flattened array of ordinate pairs, we reconstitute them into a 
* ArrayList of Coordinate objects 
* 
* @param rawArray : [x1,y1,x2,y2,...] 
* @return a ArrayList of Coordinates 
*/ 
private ArrayList<Coordinate> coordArrayToArrayList(int[] rawArray) { 
    ArrayList<Coordinate> coordArrayList = new ArrayList<Coordinate>(); 

    int coordCount = rawArray.length; 
    for (int index = 0; index < coordCount; index += 2) { 
     Coordinate c = new Coordinate(rawArray[index], rawArray[index + 1]); 
     coordArrayList.add(c); 
    } 
    return coordArrayList; 
} 

/** 
* Restore game state if our process is being relaunched 
* 
* @param icicle a Bundle containing the game state 
*/ 
public void restoreState(Bundle icicle) { 
    setMode(PAUSE); 

    mAppleList = coordArrayToArrayList(icicle.getIntArray("mAppleList")); 
    mDirection = icicle.getInt("mDirection"); 
    mNextDirection = icicle.getInt("mNextDirection"); 
    mMoveDelay = icicle.getLong("mMoveDelay"); 
    mScore = icicle.getLong("mScore"); 
    mSnakeTrail = coordArrayToArrayList(icicle.getIntArray("mSnakeTrail")); 
} 

/* 
* handles key events in the game. Update the direction our snake is traveling 
* based on the DPAD. Ignore events that would cause the snake to immediately 
* turn back on itself. 
* 
* (non-Javadoc) 
* 
* @see android.view.View#onKeyDown(int, android.os.KeyEvent) 
*/ 
@Override 
public boolean onKeyDown(int keyCode, KeyEvent msg) { 

    if (keyCode == KeyEvent.KEYCODE_DPAD_UP) { 
     if (mMode == READY | mMode == LOSE) { 
      /* 
      * At the beginning of the game, or the end of a previous one, 
      * we should start a new game. 
      */ 
      initNewGame(); 
      setMode(RUNNING); 
      update(); 
      return (true); 
     } 

     if (mMode == PAUSE) { 
      /* 
      * If the game is merely paused, we should just continue where 
      * we left off. 
      */ 
      setMode(RUNNING); 
      update(); 
      return (true); 
     } 

     if (mDirection != SOUTH) { 
      mNextDirection = NORTH; 
     } 
     return (true); 
    } 

    if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) { 
     if (mDirection != NORTH) { 
      mNextDirection = SOUTH; 
     } 
     return (true); 
    } 

    if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) { 
     if (mDirection != EAST) { 
      mNextDirection = WEST; 
     } 
     return (true); 
    } 

    if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) { 
     if (mDirection != WEST) { 
      mNextDirection = EAST; 
     } 
     return (true); 
    } 

    return super.onKeyDown(keyCode, msg); 
} 

public void loadSound(){ 
    sounds = new SoundPool(3, AudioManager.STREAM_MUSIC, 0); 

    try{ 
     //Create objects for the required classes 
     AssetManager assetManager = m_context.getAssets(); 
     AssetFileDescriptor descriptor; 

     //Create the three sound effects in memory 
       descriptor = assetManager.openFd("wall.ogg"); 
     ulose = sounds.load(descriptor, 0); 

     descriptor = assetManager.openFd("apple.ogg"); 
     apple = sounds.load(descriptor, 0); 

     descriptor = assetManager.openFd("tiles.ogg"); 
     moving = sounds.load(descriptor, 0); 
    } 
    catch (IOException e){ 
     Log.e("error", "failed to load sound files"); 
    } 
} 

/** 
* Sets the TextView that will be used to give information (such as "Game 
* Over" to the user. 
* 
* @param newView 
*/ 
public void setTextView(TextView newView) { 
    mStatusText = newView; 
} 

/** 
* Updates the current mode of the application (RUNNING or PAUSED or the like) 
* as well as sets the visibility of textview for notification 
* 
* @param newMode 
*/ 
public void setMode(int newMode) { 
    int oldMode = mMode; 
    mMode = newMode; 

    if (newMode == RUNNING & oldMode != RUNNING) { 
     mStatusText.setVisibility(View.INVISIBLE); 
     update(); 
     return; 
    } 

    Resources res = getContext().getResources(); 
    CharSequence str = ""; 
    if (newMode == PAUSE) { 
     str = res.getText(R.string.mode_pause); 
    } 
    if (newMode == READY) { 
     str = res.getText(R.string.mode_ready); 
    } 
    if (newMode == LOSE) { 
     str = res.getString(R.string.mode_lose_prefix) + mScore 
       + res.getString(R.string.mode_lose_suffix); 
    } 

    mStatusText.setText(str); 
    mStatusText.setVisibility(View.VISIBLE); 
} 

/** 
* Selects a random location within the garden that is not currently covered 
* by the snake. Currently _could_ go into an infinite loop if the snake 
* currently fills the garden, but we'll leave discovery of this prize to a 
* truly excellent snake-player. 
* 
*/ 
private void addRandomApple() { 
    Coordinate newCoord = null; 
    boolean found = false; 
    while (!found) { 
     // Choose a new location for our apple 
     int newX = 1 + RNG.nextInt(mXTileCount - 2); 
     int newY = 1 + RNG.nextInt(mYTileCount - 2); 
     newCoord = new Coordinate(newX, newY); 

     // Make sure it's not already under the snake 
     boolean collision = false; 
     int snakelength = mSnakeTrail.size(); 
     for (int index = 0; index < snakelength; index++) { 
      if (mSnakeTrail.get(index).equals(newCoord)) { 
       collision = true; 
      } 
     } 
     // if we're here and there's been no collision, then we have 
     // a good location for an apple. Otherwise, we'll circle back 
     // and try again 
     found = !collision; 
    } 
    if (newCoord == null) { 
     Log.e(TAG, "Somehow ended up with a null newCoord!"); 
    } 
    mAppleList.add(newCoord); 
} 


/** 
* Handles the basic update loop, checking to see if we are in the running 
* state, determining if a move should be made, updating the snake's location. 
*/ 
public void update() { 
    if (mMode == RUNNING) { 
     long now = System.currentTimeMillis(); 

     if (now - mLastMove > mMoveDelay) { 
      clearTiles(); 
      updateWalls(); 
      updateSnake(); 
      updateApples(); 
      mLastMove = now; 
     } 
     mRedrawHandler.sleep(mMoveDelay); 
    } 

} 

/** 
* Draws some walls. 
* 
*/ 
private void updateWalls() { 
    for (int x = 0; x < mXTileCount; x++) { 
     setTile(GREEN_STAR, x, 0); 
     setTile(GREEN_STAR, x, mYTileCount - 1); 
    } 
    for (int y = 1; y < mYTileCount - 1; y++) { 
     setTile(GREEN_STAR, 0, y); 
     setTile(GREEN_STAR, mXTileCount - 1, y); 
    } 
} 

/** 
* Draws some apples. 
* 
*/ 
private void updateApples() { 
    for (Coordinate c : mAppleList) { 
     setTile(YELLOW_STAR, c.x, c.y); 
    } 
} 



/** 
* Figure out which way the snake is going, see if he's run into anything (the 
* walls, himself, or an apple). If he's not going to die, we then add to the 
* front and subtract from the rear in order to simulate motion. If we want to 
* grow him, we don't subtract from the rear. 
* 
*/ 
private void updateSnake() { 
    boolean growSnake = false; 

    // grab the snake by the head 
    Coordinate head = mSnakeTrail.get(0); 
    Coordinate newHead = new Coordinate(1, 1); 

    mDirection = mNextDirection; 

    switch (mDirection) { 
    case EAST: { 
     newHead = new Coordinate(head.x + 1, head.y); 
     sounds.play(moving, 1.0f, 1.0f, 0, 0, 1.5f); 
     break; 
    } 
    case WEST: { 
     newHead = new Coordinate(head.x - 1, head.y); 
     sounds.play(moving, 1.0f, 1.0f, 0, 0, 1.5f); 
     break; 
    } 
    case NORTH: { 
     newHead = new Coordinate(head.x, head.y - 1); 
     sounds.play(moving, 1.0f, 1.0f, 0, 0, 1.5f); 
     break; 
    } 
    case SOUTH: { 
     newHead = new Coordinate(head.x, head.y + 1); 
     sounds.play(moving, 1.0f, 1.0f, 0, 0, 1.5f); 
     break; 
    } 
    } 

    // Collision detection 
    // For now we have a 1-square wall around the entire arena 
    if ((newHead.x < 1) || (newHead.y < 1) || (newHead.x > mXTileCount - 2) 
      || (newHead.y > mYTileCount - 2)) { 
     sounds.play(ulose, 1.0f, 1.0f, 0, 0, 1.5f); 
     setMode(LOSE); 
     return; 

    } 

    // Look for collisions with itself 
    int snakelength = mSnakeTrail.size(); 
    for (int snakeindex = 0; snakeindex < snakelength; snakeindex++) { 
     Coordinate c = mSnakeTrail.get(snakeindex); 
     if (c.equals(newHead)) { 
      sounds.play(ulose, 1.0f, 1.0f, 0, 0, 1.5f); 
      setMode(LOSE); 
      return; 
     } 
    } 

    // Look for apples 
    int applecount = mAppleList.size(); 
    for (int appleindex = 0; appleindex < applecount; appleindex++) { 
     Coordinate c = mAppleList.get(appleindex); 
     if (c.equals(newHead)) { 
      sounds.play(apple, 1.0f, 1.0f, 0, 0, 1.5f); 
      mAppleList.remove(c); 
      addRandomApple(); 

      mScore++; 
      mMoveDelay *= 0.9; 

      growSnake = true; 
     } 
    } 

    // push a new head onto the ArrayList and pull off the tail 
    mSnakeTrail.add(0, newHead); 
    // except if we want the snake to grow 
    if (!growSnake) { 
     mSnakeTrail.remove(mSnakeTrail.size() - 1); 
    } 

    int index = 0; 
    for (Coordinate c : mSnakeTrail) { 
     if (index == 0) { 
      setTile(YELLOW_STAR, c.x, c.y); 
     } else { 
      setTile(RED_STAR, c.x, c.y); 
     } 
     index++; 
    } 

} 

/** 
* Simple class containing two integer values and a comparison function. 
* There's probably something I should use instead, but this was quick and 
* easy to build. 
* 
*/ 
private class Coordinate { 
    public int x; 
    public int y; 

    public Coordinate(int newX, int newY) { 
     x = newX; 
     y = newY; 
    } 

    public boolean equals(Coordinate other) { 
     if (x == other.x && y == other.y) { 
      return true; 
     } 
     return false; 
    } 

    @Override 
    public String toString() { 
     return "Coordinate: [" + x + "," + y + "]"; 
    } 
} 

を拡張します}私のために、私は自分がどこで過ちを犯したのかを知ることができただけです。私はこれを意図どおりに学ぶことができるように、それらを修正するoperアプローチです。どんな提案も大歓迎です。

Answer 1

（1）loadSound（）メソッドを呼び出すようには思われません。
soundPoolオブジェクトはインスタンス化されません。これは取得したエラーです。
loadSound（）メソッドを呼び出す必要があります。

（2）の値にあなたの設定していないm_contextは、次の操作を行います。

m_context = getApplicationContext(); 

（3）生のディレクトリからサウンドをロードするための簡単な方法があります：

apple = soundsload(getApplicationContext(),R.raw.apple,1);