即使使用构造函数后，我也得到空对象引用

Question

这是运行日志：

  

java.lang.NullPointerException：尝试在com.Karbi.chonang.FoodDetail $ 1.onClick上的空对象引用上调用虚拟方法'java.lang.String com.Karbi.chonang.Model.Food.getName（）'。 （FoodDetail.java:57）

我的代码：

TextView food_name,food_price,food_description;
ImageView img_food;
CollapsingToolbarLayout collapsingToolbarLayout;
FloatingActionButton btnCart;
ElegantNumberButton numberButton;

String foodId="";
FirebaseDatabase database;
DatabaseReference foods;

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

    //Firebase
    database = FirebaseDatabase.getInstance();
    foods= database.getReference("Foods");


    //Init view
    numberButton = (ElegantNumberButton)findViewById(R.id.number_button);
    btnCart = (FloatingActionButton)findViewById(R.id.btnCart);


    btnCart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            new Database(getBaseContext()).addToCart(new Order(
                    foodId,
                    currentFood.getName(),
                    numberButton.getNumber(),
                    currentFood.getPrice(),
                    currentFood.getDiscount()

            ));

            Toast.makeText(FoodDetail.this, "Added to your Cart", Toast.LENGTH_SHORT).show();
        }


    });

    food_description = (TextView)findViewById(R.id.food_description);
    food_name = (TextView)findViewById(R.id.food_name);
    food_price = (TextView)findViewById(R.id.food_price);
    img_food = (ImageView)findViewById(R.id.img_food);

    collapsingToolbarLayout = (CollapsingToolbarLayout)findViewById(R.id.collapsing);
    collapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.ExpandedAppbar);
    collapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.CollapseAppbar);


    //Get Food Id from Intent

    if (getIntent()!=null)

        foodId = getIntent().getStringExtra("FoodId");
    if(foodId.isEmpty())
    {
        getDetailFood(foodId);
    }

}

private void getDetailFood(String foodId) {

    foods.child(foodId).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            currentFood= dataSnapshot.getValue(Food.class);

            //set Image
            Picasso.with(getBaseContext()).load(currentFood.getImage())
                    .into(img_food);

            collapsingToolbarLayout.setTitle(currentFood.getName());

            food_price.setText(currentFood.getPrice());

            food_name.setText(currentFood.getName());

            food_description.setText(currentFood.getDescription());
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}
}

我检查了构造函数，已经调用了变量，甚至返回了它。