Android game an collision

I have a many sprites walking on the screen. If the sprite s1 collides with sprite2, both sprites should play a sound (or similar).

I have created a game loop:

public void run( )
{
    long startTime;
    long sleepTime;

    while (this.running)
    {
        startTime = System.currentTimeMillis();


        this.view.updatePhysics( );

        Canvas canvas = null;
        try
        {
            canvas = this.view.getHolder( ).lockCanvas( );
            synchronized (this.view.getHolder( ))
            {
                this.view.onDraw( canvas );
            }
        }
        finally
        {
            if (canvas != null)
                this.view.getHolder( ).unlockCanvasAndPost( canvas );
        }

        sleepTime = TICS_PRO_SECOND - ( System.currentTimeMillis( ) - startTime );

        try
        {
            if (sleepTime > 0)
                GameLoop.sleep( sleepTime );
            else
                GameLoop.sleep( 500 );
        }
        catch (Exception exception)
        {
        }

    }
}

The updatePhysics() is called many times. If I use a debugger I can see, that the code execution in collideWith( Sprite sprite ) comes up to return true, but jump to the next line an return false. I think, it is a synchr开发者_JAVA百科onisation problem...

Where I should call the collision method in my game loop? Is the update() the right place? I think, it isn't ;) . The sprite.onCollision( ) is called very rare...

protected void updatePhysics( )
{
    for (Sprite sprite : sprites)
    {

            for (Sprite s : sprites)
            {
                if (sprite.collideWith( s ))
                    sprite.onCollision( );
            }

        sprite.update( );
    }
}


public boolean collideWith( Sprite sprite )
{
    if (this == sprite)
        return false;

    Rect thisSprite = new Rect( this.xCoordinate, this.yCoordinate, this.width, this.height );
    Rect anotherSprite = new Rect( sprite.xCoordinate, sprite.yCoordinate, sprite.width, sprite.height );

    if (thisSprite.intersect( anotherSprite ))
        return true;

    return false;
}

Should I synchronized the collideWith() method? Or is my code

for (Sprite sprite : sprites)
    {

            for (Sprite s : sprites)
            {
                if (sprite.collideWith( s ))
                    sprite.onCollision( );
            }

        sprite.update( );
    }

the problem?

Regards, Dulcinea