java 什么是类型和类型令牌？
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What is Type & TypeToken?
提问by Android
I have the following method in my project
我的项目中有以下方法
public void execute(final int apiId, final ResponseHandler handler, final Type type)
and the type is determined using TypeToken as follows
类型是使用 TypeToken 确定的，如下所示
final Type serviceErrorType = new TypeToken<>() {
}.getType();
I went through this linkhere but couldn't understand completely about Typeand TypeToken
我在这里浏览了这个链接，但无法完全理解Type和TypeToken
Can anyone please share a link or help understand these two concepts?
任何人都可以分享链接或帮助理解这两个概念吗？
回答by azizbekian
From the linkyou provided:
从您提供的链接：
Forces clients to create a subclass of this class which enables retrieval the type information even at runtime.
强制客户端创建此类的子类，即使在运行时也可以检索类型信息。
Let's speak with example.
让我们用例子说话。
Assume you want to parse a JSON to Java class with Gsonlibrary. Now, you have to specifically tell Gson, that:
假设您想使用Gson库将 JSON 解析为 Java 类。现在，您必须特别告诉 Gson：
I want this JSON to be translated to a Listof Userobjects
我想这个JSON被翻译成一个列表的用户对象
How would you tell that to Gson? If it was only User, you could tell User.class. But it isn't possible to say List<User>.class
你会怎么告诉 Gson 呢？如果只是User，你能看出来User.class。但不能说List<User>.class
new Gson().fromJson(json, new TypeToken<List<User>>(){}.getType())
But now you can specify precisely that Gson should convert it to a List of Users.
但是现在您可以精确地指定 Gson 应该将其转换为List of Users.
Should quote explanation from docs:
应该引用文档中的解释：
Represents a generic type
T. Java doesn't yet provide a way to represent generic types, so this class does.
代表一个泛型类型
T。Java 还没有提供表示泛型类型的方法，所以这个类提供了。
Have a look at this blog postfor more details on the topic.
有关该主题的更多详细信息，请查看此博客文章。
