如何检查double值是否为空

i'm trying to get Double value from json, i want to ask how to check double value is empty or not?

我想从json获得Double值,我想问一下如何检查double值是否为空?

this is how i initial it private static

这是我初始化私有静态的方式

final String kartu_xcord = "xcord";
    private static final String kartu_ycord = "ycord";
    ouble xcord,ycord;

this is how i parse my json:

这是我解析我的json的方式:

xcord = c.getDouble(kartu_xcord);
ycord = c.getDouble(kartu_ycord);

this is how i try to check xcord is null or empty :

这是我试图检查xcord是null还是空:

if (xcord.isNaN()) {
            LinlayNoMap.setVisibility(View.VISIBLE);
        } else {
            linlaymap.setVisibility(View.VISIBLE);
}

i hope someone can help me to solve my proble thank you

我希望有人能帮我解决问题谢谢你

7 个解决方案

#1

Make it to Double not double and check if Double value is null, in java double value can not be null.

使它成为Double而不是double并检查Double值是否为null,在java double值中不能为null。

#2

In Java double cannot be null.

在Java中,double不能为null。

#3

It can't be null or empty. It's a double value. Maybe try the Double wrapper?

它不能为null或为空。这是双重价值。也许试试Double包装?

#4

You could check if your json has the key you area looking for:

您可以检查您的json是否具有您所在区域的关键字:

if (c.hasDouble("my_coord")) {
  y_coord = c.getDouble("my_coord");
}

if y_coord is a Double (with capital D), you can set it to null.

如果y_coord是Double(使用大写D),则可以将其设置为null。

if (c.hasDouble("my_coord")) {
  y_coord = c.getDouble("my_coord");
} else {
  y_coord = null;
}

This depends of course on the API you are using to read your JSON, the hasDouble method could be called something else. I recommend you give a try to GSON, very simple and will handle most of the parsing work for you.

这当然取决于您用来读取JSON的API,hasDouble方法可以被称为其他方法。我建议你试试GSON,非常简单,并将为你处理大部分的解析工作。

#5

doubles can never be null in Java. You can instead use the hasKey method of Json to check if the item you're parsing contains the value.

Java中的双精度数永远不会为空。您可以改为使用Json的hasKey方法来检查您正在解析的项是否包含该值。

c.hasKey("xcord")

#6

assume you are using JSONObject, you can do this

假设您正在使用JSONObject,您可以这样做

xcord = c.optDouble(kartu_xcord, Double.MIN_VALUE);

if (xcord == Double.MIN_VALUE){
  //xcord is empty
}

#7

-1

Use Double, not double.

使用Double,而不是double。

Double  dValue= someVariable;

if(!dValue.isNaN())
{
 // you code here
}

#1