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This article will explain in detail for you how to write a TypeAdapter and register TypeAdapter and deal with the Enum type. The content of the article is of high quality, so the editor shares it for you to do a reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Enumerated types bring benefits to our program, how to use Gson to achieve interconversion with Json? Please read this article.

How to write a TypeAdapter and register TypeAdapter and handle Enum types yourself.

Entity class:

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Public enum PackageState {

PLAY, UPDATE, UPDATING, DOWNLOAD, DOWNLOADING

}

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Public class PackageItem {

Private String name

Private PackageState state

Private String size

Public String getName () {

Return name

}

Public void setName (String name) {

This.name = name

}

Public PackageState getState () {

Return state

}

Public void setState (PackageState state) {

This.state = state

}

Public String getSize () {

Return size

}

Public void setSize (String size) {

This.size = size

}

@ Override

Public String toString () {

Return "PackageItem [name=" + name + ", size=" + size + ", state="

+ state + "]"

}

}

Write a converter to implement JsonSerializer interface and jsonDeserializer interface:

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Mport java.lang.reflect.Type

Import com.google.gson.JsonDeserializationContext

Import com.google.gson.JsonDeserializer

Import com.google.gson.JsonElement

Import com.google.gson.JsonParseException

Import com.google.gson.JsonPrimitive

Import com.google.gson.JsonSerializationContext

Import com.google.gson.JsonSerializer

Public class EnumSerializer implements JsonSerializer

JsonDeserializer {

/ / it is called when the object is converted to Json to implement the JsonSerializer interface

@ Override

Public JsonElement serialize (PackageState state, Type arg1

JsonSerializationContext arg2) {

Return new JsonPrimitive (state.ordinal ())

}

/ / json is called when it is converted to an object to implement the JsonDeserializer interface

@ Override

Public PackageState deserialize (JsonElement json, Type typeOfT

JsonDeserializationContext context) throws JsonParseException {

If (json.getAsInt () < PackageState.values () .length)

Return PackageState.values () [json.getAsInt ()]

Return null

}

}

Test class:

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Import com.google.gson.Gson

Import com.google.gson.GsonBuilder

Public class GsonTest6 {

Public static void main (String [] args) {

GsonBuilder gsonBuilder = new GsonBuilder ()

GsonBuilder.registerTypeAdapter (PackageState.class

New EnumSerializer ()

Gson gson = gsonBuilder.create ()

PackageItem item = new PackageItem ()

Item.setName ("item_name")

Item.setSize ("500m")

Item.setState (PackageState.UPDATING); / / this state is an enumerated value

String s = gson.toJson (item)

System.out.println (s)

System.out.println ("-")

PackageItem retItem = gson.fromJson (s, PackageItem.class)

System.out.println (retItem)

}

}

Output result (the corresponding enumeration type of state has been changed to int type in the result):

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{"name": "item_name", "state": 2, "size": "500m"}

-

PackageItem [name=item_name, size=500M, state=UPDATING]

Classification: JSP

Tags: Enum, Gson, json, TypeAdapter, instance

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