Gson将float解析为int

Question

我错误地将代码中的json字段： "mileage":0.0"解析为一个int 。它被成功解析，直到值为0.0 。但是，一旦json字段的值从0.0更改为任何其他值，我就开始越来越JsonFormatException我使用GSON在我的应用程序解析JSON。所以我的问题是为什么没有异常没有被当值抛出0.0的原因，它仍然漂浮？

Answer 1

Exactly how Gson works depends on how you were doing the deserialization. I'm going to bet that you were letting it do deserialization automatically, likely driven by the @SerializedName annotation. So let's assume you have some class with something like this in it:

@SerializedName("val")
private int myValue;

When Gson deserializes text into an instance of your object, it will "do its best" to give you what you want. This includes coercing some values from one type to another. For a class set up like the above, Gson will not only successfully coerce 0.0 into 0 , it will also successfully coerce "1.0" (a String) into 1 .

You will only get an Exception when the coercion is "impossible"; as soon as you have 0.1 or "1.5" , Gson knows that it can't represent that value as an int and so it throws an exception.

Note that this works in both directions. If your json includes an integer number (eg {"val":3} ) but your class declares private String myValue , Gson will successfully coerce the number to "3" .