计数剩余天数

Question

我正在创建一个小应用程序，记录用户在冰箱/冰柜中的使用情况。 有一个列表视图的形式的产品的列表，用户可以添加新产品。当添加新的时候，我们可以选择一个失效日期，应用程序应该能够计算剩余的天数。我有一个adapter和几个activities，但不知道每天的天数是否会改变？有什么其他方式可以做到吗？这里是我的代码：

public class Product implements Serializable { 
/** 
* The name of the food product 
*/ 
private String name; 
/** 
* The quantity of product 
*/ 
private int quantity; 

private Metrics measure; 
/** 
* The expiry date of the product 
*/ 
private Date expiry; 
/** 
* The price of the product 
*/ 
private double price; 
/** 
* The shelf life of the product 
*/ 
private int shelfLife; 
/** 
* 
*/ 
private FoodCategory foodType; 

/** 
* 
* @param aName 
* @param aQuantity 
* @param anExpiry 
* @param aPrice 
*/ 
public Product(String aName, int aQuantity, Metrics aMeasure, Date anExpiry, double aPrice, FoodCategory aType) 
{ 
    this.name = aName; 
    this.quantity = aQuantity; 
    this.measure = aMeasure; 
    this.price = aPrice; 
    this.expiry = anExpiry; 
    this.foodType = aType; 
    Date date = new Date(); 
    this.shelfLife = (int)(anExpiry.getTime()-date.getTime())/(1000 * 60 * 60 * 24); 
} 

/** 
* Returns the name of the product 
* 
* @return name 
*/ 
public String getName() 
{ 
    return name; 
} 

/** 
* 
* @param aName 
*/ 
public void setName(String aName) 
{ 
    this.name = aName; 
} 
/** 
* Returns the quantity of the product 
* @return quantity 
*/ 
public int getQuantity() 
{ 
    return quantity; 
} 

public Metrics getMetric() 
{ 
    return measure; 
} 

/** 
* 
* @param aQuantity 
*/ 
public void setQuantity(int aQuantity) 
{ 
    this.quantity = aQuantity; 
} 
/** 
* Returns the price of the product 
* @return price 
*/ 
public double getPrice() 
{ 
    return price; 
} 

/** 
* 
* @param aPrice 
*/ 
public void setPrice(double aPrice) 
{ 
    this.price = aPrice; 
} 
/** 
* Returns the number of days of the shelf life of product 
* @return shelfLife 
*/ 
public int getShelfLife() 
{ 
    return shelfLife; 
} 
/** 
* 
* @return String representation of Product object 
*/ 

public FoodCategory getFoodType() 
{ 
    return foodType; 
} 

public void setFoodType(FoodCategory aType) 
{ 
    this.foodType = aType; 
} 

@Override 
public String toString() 
{ 
    return name + " " + quantity + " " + price + " " + expiry + " " + shelfLife; 
} 

} 




public class ProductAdapter extends BaseAdapter { 

Context context; 
ArrayList<Product> products; 

public ProductAdapter(Context context, ArrayList<Product> products) 
{ 
    this.context = context; 
    this.products = products; 
} 
@Override 
public int getCount() { 
    return products.size(); 
} 

@Override 
public Object getItem(int position) { 
    return null; 
} 

@Override 
public long getItemId(int position) { 
    return 0; 
} 

@Override 
public View getView(int position, View convertView, ViewGroup parent) { 
    if(convertView == null) 
    { 
     LayoutInflater layoutInflater = (LayoutInflater) this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     convertView = layoutInflater.inflate(R.layout.listview_product,null); 
    } 
    TextView name = (TextView) convertView.findViewById(R.id.name); 
    TextView quantity = (TextView) convertView.findViewById(R.id.quantity); 
    TextView metric = (TextView) convertView.findViewById(R.id.metric); 
    TextView expiry = (TextView) convertView.findViewById(R.id.expiry); 

    Product newProduct = products.get(position); 
    name.setText(newProduct.getName()); 
    int q = newProduct.getQuantity(); 
    String s = String.valueOf(q); 
    quantity.setText(s); 
    metric.setText(newProduct.getMetric().toString()); 
    int d = newProduct.getShelfLife(); 
    String ss = String.valueOf(d); 
    expiry.setText(ss + " day/s left"); 
    System.getProperty("line.separator"); 
    return convertView; 
} 

}

Answer 1

这是年，月一般日期计数器。如果您只需要几天，则可以省略（年和月）相关代码。

Calendar thatDay = Calendar.getInstance(); 
     thatDay.set(Calendar.DAY_OF_MONTH,25); 
     thatDay.set(Calendar.MONTH,7); // 0-11 so 1 less thatDay.set(Calendar.YEAR, 1985); 

     Calendar today = Calendar.getInstance(); 

     long diff = today.getTimeInMillis() - thatDay.getTimeInMillis(); //result in millis 

下面是一个近似值......

long days = diff/(24 * 60 * 60 * 1000); 

如果你正在开发一个火力地堡的应用程序，然后让我知道。