blocks|key|2256318|text|原因：发生此错误是因为杰克逊库不知道如何创建没有空构造函数的模型，而模型包含的构造函数没有用@JsonProperty("field_name")对参数进行注释。默认情况下，如果没有向类添加构造函数，java编译器将创建空构造函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|2256319|解决方案：向模型中添加一个空构造函数或用@JsonProperty("field_name")注释构造函数参数|2256320|如果您使用Kotlin数据类，那么也可以使用@JsonProperty("field_name")进行注释或将jackson模块kotlin注册到ObjectMapper。|2256321|您可以使用http://www.jsonschema2pojo.org/创建模型。|2256322|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/FasterXML/jackson-module-kotlin|1|http://www.jsonschema2pojo.org/^0|0|3|1A|R|0|0|5|K|R|0|M|R|21|C|1J|F|0|0|5|V|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|D]]|E|@]|F|$]]|$1|I|3|J|5|6|7|16|8|@$9|17|A|18|B|D]|$9|19|A|1A|B|D]]|E|@$9|1B|A|1C|1|1D]]|F|$]]|$1|K|3|L|5|6|7|1E|8|@]|E|@$9|1F|A|1G|1|1H]]|F|$]]|$1|M|3|-4|5|6|7|1I|8|@]|E|@]|F|$]]]|N|$O|$5|P|Q|R|F|$S|T]]|U|$5|P|Q|R|F|$S|V]]]]

Reason: This error occurs because jackson library doesn't know how to create your model which doesn't have an empty constructor and the model contains constructor with parameters which didn't annotated its parameters with <code>@JsonProperty(&quot;field_name&quot;)</code>. By default java compiler creates empty constructor if you didn't add constructor to your class.
Solution:
Add an empty constructor to your model or annotate constructor parameters with <code>@JsonProperty(&quot;field_name&quot;)</code>
If you use a Kotlin data class then also can annotate with <code>@JsonProperty(&quot;field_name&quot;)</code> or register <a href="https://github.com/FasterXML/jackson-module-kotlin" rel="noreferrer">jackson module kotlin</a> to <code>ObjectMapper</code>.
You can create your models using <a href="http://www.jsonschema2pojo.org/" rel="noreferrer">http://www.jsonschema2pojo.org/</a>.

blocks|key|2256354|text|我在这里寻找这个错误：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2256355|No+Creators,+like+default+construct,+exist):+cannot+deserialize+from+Object+value+(no+delegate-+or+property-based+Creator|code-block|syntax|javascript|2256356|与Retrofit无关，但是如果您正在使用Jackson，则通过向抛出错误的类添加默认构造函数来解决此错误。这里有更多信息：https://www.baeldung.com/jackson-exception|offset|length|2256357|entityMap|0|LINK|mutability|MUTABLE|url|https://www.baeldung.com/jackson-exception^0|0|0|1Q|16|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I got here searching for this error:

<pre><code>No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator
</code></pre>

Nothing to do with Retrofit but if you are using Jackson this error got solved by adding a default constructor to the class throwing the error.
More here: <a href="https://www.baeldung.com/jackson-exception" rel="noreferrer">https://www.baeldung.com/jackson-exception</a>

blocks|key|2256497|text|如果在POJO模型上使用Lombok，请确保有以下注释：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2256498|@Getter
@Builder
@NoArgsConstructor
@AllArgsConstructor|code-block|syntax|javascript|2256499|它可能会有所不同，但要确保@Getter和，特别是|CODE|2256500|entityMap^0|C|6|0|0|D|7|L|4|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|S|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|T|8|@$9|U|A|V|B|M]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|N|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|O|$]]

If you're using Lombok on a POJO model, make sure you have these annotations:

<pre class="lang-java prettyprint-override"><code>@Getter
@Builder
@NoArgsConstructor
@AllArgsConstructor
</code></pre>

It could vary, but make sure <code>@Getter</code> and especially <code>@NoArgsConstructor</code>.

blocks|key|2256256|text|您需要使用jackson-module-kotlin将数据类反序列化。详情请参见这里。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2256257|上面的错误消息是如果您试图在某个模块未启用时将某些值反序列化为一个数据类，或者即使是这样，当它使用的ObjectMapper没有注册KotlinModule时，会给您带来什么错误信息。例如，以以下代码为例：|2256258|data+class+TestDataClass+(val+foo:+String)

val+jsonString+=+"""{+"foo":+"bar"+}"""
val+deserializedValue+=+ObjectMapper().readerFor(TestDataClass::class.java).readValue<TestDataClass>(jsonString)|code-block|syntax|javascript|2256259|如果出现以下错误，这将失败：|2256260|com.fasterxml.jackson.databind.exc.MismatchedInputException:+Cannot+construct+instance+of+`test.SerializationTests$TestDataClass`+(although+at+least+one+Creator+exists):+cannot+deserialize+from+Object+value+(no+delegate-+or+property-based+Creator)|2256261|如果您更改了上面的代码并将ObjectMapper替换为jacksonObjectMapper+(它只是返回一个普通的ObjectMapper并注册了KotlinModule+)，那么它就能工作了。即|2256262|val+deserializedValue+=+jacksonObjectMapper().readerFor(TestDataClass::class.java).readValue<TestDataClass>(jsonString)|2256263|我不确定Android方面的情况，但看起来您需要让系统使用jacksonObjectMapper进行反序列化。|2256264|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/FasterXML/jackson-module-kotlin^0|5|L|14|2|0|0|1E|C|1U|C|0|0|0|0|D|C|S|J|1N|C|23|C|0|0|T|J|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@$9|17|A|18|1|19]]|E|$]]|$1|F|3|G|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1F|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1G|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1H|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1I|8|@$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1R|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1S|8|@$9|1T|A|1U|B|C]]|D|@]|E|$]]|$1|W|3|-4|5|6|7|1V|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

You need to use <code>jackson-module-kotlin</code> to deserialize to data classes. See <a href="https://github.com/FasterXML/jackson-module-kotlin" rel="noreferrer">here</a> for details.

The error message above is what Jackson gives you if you try to deserialize some value into a data class when that module isn't enabled or, even if it is, when the <code>ObjectMapper</code> it uses doesn't have the <code>KotlinModule</code> registered. For example, take this code:

<pre><code>data class TestDataClass (val foo: String)

val jsonString = """{ "foo": "bar" }"""
val deserializedValue = ObjectMapper().readerFor(TestDataClass::class.java).readValue&lt;TestDataClass&gt;(jsonString)
</code></pre>

This will fail with the following error:

<pre><code>com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `test.SerializationTests$TestDataClass` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator)
</code></pre>

If you change the code above and replace <code>ObjectMapper</code> with <code>jacksonObjectMapper</code> (which simply returns a normal <code>ObjectMapper</code> with the <code>KotlinModule</code> registered), it works. i.e.

<pre><code>val deserializedValue = jacksonObjectMapper().readerFor(TestDataClass::class.java).readValue&lt;TestDataClass&gt;(jsonString)
</code></pre>

I'm not sure about the Android side of things, but it looks like you'll need to get the system to use the <code>jacksonObjectMapper</code> to do the deserialization.

blocks|key|1413784|text|我知道这是一个旧的帖子，但是对于任何使用Retrofit的人来说，这可能是有用的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1413785|如果使用Retrofit+%2B+Jackson+%2B+Kotlin+%2B+Data类，则需要：|1413786|将implement+group:+'com.fasterxml.jackson.module',+name:+'jackson-module-kotlin',+version:+'2.7.1-2'添加到您的依赖项中，以便Jackson可以反序列化为数据类。|ordered-list-item|offset|length|style|CODE|1413787|在进行建筑改造时，请传递Kotlin+Jackson+Mapper，以便retrofit使用正确的映射器，例如：|1413788|++++val+jsonMapper+=+com.fasterxml.jackson.module.kotlin.jacksonObjectMapper()

++++val+retrofit+=+Retrofit.Builder()
++++++++++...
++++++++++.addConverterFactory(JacksonConverterFactory.create(jsonMapper))
++++++++++.build()|code-block|syntax|javascript|1413789|注意:如果没有使用Retrofit，@Jayson有一个更通用的方法。|1413790|entityMap^0|0|0|1|2Q|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|X|8|@$G|Y|H|Z|I|J]]|9|@]|A|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|A|$]]|$1|M|3|N|5|O|7|11|8|@]|9|@]|A|$P|Q]]|$1|R|3|S|5|6|7|12|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|U|$]]

I know this is an old post, but for anyone using Retrofit, this can be useful useful.

If you are using Retrofit + Jackson + Kotlin + Data classes, you need: 

<ol>
<li>add <code>implement group: 'com.fasterxml.jackson.module', name: 'jackson-module-kotlin', version: '2.7.1-2'</code> to your dependencies, so that Jackson can de-serialize into Data classes</li>
<li>When building retrofit, pass the Kotlin Jackson Mapper, so that Retrofit uses the correct mapper, ex:</li>
</ol>

<pre><code> val jsonMapper = com.fasterxml.jackson.module.kotlin.jacksonObjectMapper()

 val retrofit = Retrofit.Builder()
 ...
 .addConverterFactory(JacksonConverterFactory.create(jsonMapper))
 .build()
</code></pre>

Note: If Retrofit is not being used, @Jayson Minard has a more general approach answer.

blocks|key|519340|text|我有一个类似的问题(使用Jackson、lombok、gradle)和一个没有args构造函数的POJO+--解决方案是添加|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519341|lombok.anyConstructor.addConstructorProperties=true|code-block|syntax|javascript|519342|到lombok.config文件。|offset|length|style|BOLD|519343|entityMap^0|0|0|1|D|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I had a similar issue (using Jackson, lombok, gradle) and a POJO without no args constructor - the solution was to add 

<pre><code>lombok.anyConstructor.addConstructorProperties=true
</code></pre>

to the lombok.config file

blocks|key|2257019|text|我用的是夸库斯，杰克逊和隆布克。因此，我通过在模型类中添加@Jacksonized属性来解决这个问题。因此，所有属性都是：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2257020|@Jacksonized+//missing
@Builder
@Data
@NoArgsConstructor
@AllArgsConstructor
public+class+...|code-block|syntax|javascript|2257021|entityMap^0|T|C|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

I am using Quarkus, Jackson and Lombok. So I solved this issue by adding <code>@Jacksonized</code> attribute on model class.
So all attributes are:
<pre><code>@Jacksonized //missing
@Builder
@Data
@NoArgsConstructor
@AllArgsConstructor
public class ...
</code></pre>

blocks|key|2256602|text|我通过添加一个无论据解释器来解决这个问题。如果使用的是Lombok，只需添加@NoArgsConstructor注释：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|2256603|@AllArgsConstructor
@NoArgsConstructor
@Getter
@ToString
@EqualsAndHashCode
public+class+User+{
++++private+Long+userId;
++++private+String+shortName;
}|code-block|syntax|javascript|2256604|entityMap^0|R|6|12|I|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|S|8|@]|E|@]|F|$J|K]]|$1|L|3|-4|5|6|7|T|8|@]|E|@]|F|$]]]|M|$]]

I solved this issue by adding a no argument constractor. If you are using Lombok, you only need to add <code>@NoArgsConstructor</code> annotation:
<pre><code>@AllArgsConstructor
@NoArgsConstructor
@Getter
@ToString
@EqualsAndHashCode
public class User {
 private Long userId;
 private String shortName;
}
</code></pre>

blocks|key|1413904|text|我在Kotlin中使用雷斯库，并使用@ConstructorProperties解析它|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1413905|++++data+class+MyResponse+@ConstructorProperties("message",+"count")+constructor(
++++++++val+message:+String,
++++++++val+count:+Int
++++)|code-block|syntax|javascript|1413906|Jackson使用@ConstructorProperties。这也应该修复Lombok+@Data。|1413907|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/mmazi/rescu^0|B|3|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

I'm using <a href="https://github.com/mmazi/rescu" rel="noreferrer">rescu</a> with Kotlin and resolved it by using @ConstructorProperties

<pre><code> data class MyResponse @ConstructorProperties("message", "count") constructor(
 val message: String,
 val count: Int
 )
</code></pre>

Jackson uses @ConstructorProperties. This should fix Lombok @Data as well.

blocks|key|1414093|text|正如前面提到的错误，该类没有默认构造函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1414094|将@NoArgsConstructor添加到实体类应该会修复它。|offset|length|1414095|entityMap|0|LINK|mutability|MUTABLE|url|https://projectlombok.org/api/lombok/NoArgsConstructor.html^0|0|1|I|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

As the error mentioned the class does not have a default constructor.

Adding <a href="https://projectlombok.org/api/lombok/NoArgsConstructor.html" rel="noreferrer">@NoArgsConstructor</a> to the entity class should fix it.

blocks|key|1414373|text|只需要添加@NoArgsConstructor就行了。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1414374|entityMap^0|5|I|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Just need to add <code>@NoArgsConstructor</code> and it works.

blocks|key|519386|text|扩展Yoni+Gibbs的答案，如果您在android项目中使用改装并与Jackson一起配置序列化，您可以做这些事情，以便反序列化工作，就像kotlin的数据类所期望的那样。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519387|在导入中：|519388|implementation+"com.fasterxml.jackson.module:jackson-module-kotlin:2.11.%2B"|code-block|syntax|javascript|519389|那么，您的改造的实施：|519390|val+serverURL+=+"http://localhost:8080/api/v1"

val+objectMapper+=+ObjectMapper()
objectMapper.registerModule(KotlinModule())
//Only+if+you+are+using+Java+8's+Time+API+too,+require+jackson-datatype-jsr310
objectMapper.registerModule(JavaTimeModule())

Retrofit.Builder()
++++.baseUrl(serverURL)
++++.client(
++++++++OkHttpClient.Builder()
+++++++++++.readTimeout(1,+TimeUnit.MINUTES)//No+mandatory
++++++++++++.connectTimeout(1,+TimeUnit.MINUTES)//No+mandatory
++++++++++++.addInterceptor(UnauthorizedHandler())//No+mandatory
++++++++++++.build())
++++.addConverterFactory(
++++++++++++++++JacksonConverterFactory.create(objectMapper)
++++++++++++)
++++.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
++++.build()|519391|数据类：|519392|@JsonIgnoreProperties(ignoreUnknown+=+true)
data+class+Task(val+id:+Int,
++++++++++++++++val+name:+String,
++++++++++++++++@JsonSerialize(using+=+LocalDateTimeSerializer::class)
++++++++++++++++@JsonDeserialize(using+=+LocalDateTimeDeserializer::class)
++++++++++++++++val+specificDate:+LocalDateTime?,
++++++++++++++++var+completed:+Boolean,
++++++++++++++++val+archived:+Boolean,
++++++++++++++++val+taskListId:+UUID?|519393|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Extending Yoni Gibbs's answer, if you are in an android project using retrofit and configure serialization with Jackson you can do these things in order to deserialization works as expected with kotlin's data class.

In your build gradle import:

<pre><code>implementation "com.fasterxml.jackson.module:jackson-module-kotlin:2.11.+"
</code></pre>

Then, your implementation of retrofit:

<pre><code>val serverURL = "http://localhost:8080/api/v1"

val objectMapper = ObjectMapper()
objectMapper.registerModule(KotlinModule())
//Only if you are using Java 8's Time API too, require jackson-datatype-jsr310
objectMapper.registerModule(JavaTimeModule())

Retrofit.Builder()
 .baseUrl(serverURL)
 .client(
 OkHttpClient.Builder()
 .readTimeout(1, TimeUnit.MINUTES)//No mandatory
 .connectTimeout(1, TimeUnit.MINUTES)//No mandatory
 .addInterceptor(UnauthorizedHandler())//No mandatory
 .build())
 .addConverterFactory(
 JacksonConverterFactory.create(objectMapper)
 )
 .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
 .build()
</code></pre>

Data class:

<pre><code>@JsonIgnoreProperties(ignoreUnknown = true)
data class Task(val id: Int,
 val name: String,
 @JsonSerialize(using = LocalDateTimeSerializer::class)
 @JsonDeserialize(using = LocalDateTimeDeserializer::class)
 val specificDate: LocalDateTime?,
 var completed: Boolean,
 val archived: Boolean,
 val taskListId: UUID?
</code></pre>

blocks|key|1414487|text|贝克的回答是正确的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1414488|但是万一有人试图在restcontroller中使用不可变类，也就是说，他们使用的是lombok的@value，那么您需要添加lombok.anyConstructor.addConstructorProperties=true|offset|length|style|CODE|1414489|您可以在根lombok.config所在的相同位置创建名为pom.xml的文件，并将该行添加到文件中。|1414490|https://stackoverflow.com/a/56022839/6700081|1414491|entityMap|0|LINK|mutability|MUTABLE|url^0|0|1D|6|1R|1F|0|5|D|0|0|18|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]|$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@$D|Z|E|10|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|L|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|K]]]]

Bek's answer is correct.
But in-case someone is trying to use immutable class in restcontroller i.e they are using lombok's <code>@value</code> then you need to add <code>lombok.anyConstructor.addConstructorProperties=true</code>
You can create a file named <code>lombok.config</code> in the same location where the root pom.xml is present and add this line into the file
<a href="https://stackoverflow.com/a/56022839/6700081">https://stackoverflow.com/a/56022839/6700081</a>

blocks|key|519428|text|我有这个问题，我修正了下面的代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519429|@Configuration
open+class+JacksonMapper+{

++++@Bean
++++open+fun+mapper():+ObjectMapper+{
++++++++val+mapper+=+ObjectMapper()
++++++++...

++++++++mapper.registerModule(KotlinModule())
++++++++return+mapper
++++}
}|code-block|syntax|javascript|519430|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I had this issue and i fixed with the code below.
<pre><code>@Configuration
open class JacksonMapper {

 @Bean
 open fun mapper(): ObjectMapper {
 val mapper = ObjectMapper()
 ...

 mapper.registerModule(KotlinModule())
 return mapper
 }
}
</code></pre>

blocks|key|1414522|text|我得到了同样的错误，在添加了一个没有参数的构造函数之后，就解决了这个问题。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1414523|​|1414524|📷|atomic|1414525|1414526|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/51389015bbaeb0826cab071b0f06a4a9.png|imageAlt^0|L|7|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|K|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S|T|-4]]]]

I got the same error and after I added a constructor without parameters and then the problem was solved.
<a href="https://i.stack.imgur.com/wsOej.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wsOej.png" alt="enter image description here" /></a>

blocks|key|520961|text|注意Lombok，特别是与@Builder。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|520962|为我解决问题的是：|520963|+++@JsonDeserialize(builder+=+X.XBuilder.class)
+++++++class+X{
++++++++++@JsonPOJOBuilder(withPrefix+=+"")
++++++++++public+static+class+XBuilder{

++++++++++}
}|code-block|syntax|javascript|520964|我希望这能让你的生活更轻松|520965|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Be carefull with Lombok, expecially with @Builder.
what fixed the issue for me was :
<pre><code> @JsonDeserialize(builder = X.XBuilder.class)
 class X{
 @JsonPOJOBuilder(withPrefix = &quot;&quot;)
 public static class XBuilder{

 }
}
</code></pre>
I hope it will make your life easier

blocks|key|1414619|text|对于没有默认构造的类，例如在处理不可变对象时，Jackson默认不能将JSON反序列化为对象。我们可以使用一些注释来解决这个问题，比如@JsonCreator，它可以帮助杰克逊知道如何反序列化给定的JSON。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1414620|示例代码如下所示：|1414621|package+com.test.hello;

import+com.fasterxml.jackson.annotation.JsonCreator;
import+com.fasterxml.jackson.annotation.JsonProperty;

public+class+Payment+{

++++private+final+Card+card;

++++private+final+Amount+amount;

++++@JsonCreator(mode+=+JsonCreator.Mode.PROPERTIES)
++++public+Payment(@JsonProperty("card")+Card+card,+@JsonProperty("amount")+Amount+amount)+{
+++++++this.card+=+card;
+++++++this.amount+=+amount;
++++}

++++public+Card+getCard()+{
+++++++return+card;
++++}

++++public+Amount+getAmount()+{
++++++++return+amount;
++++}
}|code-block|syntax|javascript|1414622|entityMap^0|1V|C|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

For classes where we don't have a default construct, example when working with immutable objects, Jackson by default will not be able to deserialize JSON to the object.
We can resolve this using some annotations like <code>@JsonCreator</code> which can help Jackson to know how to deserialize a given JSON.
A sample code will look like:
<pre><code>package com.test.hello;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

public class Payment {

 private final Card card;

 private final Amount amount;

 @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
 public Payment(@JsonProperty(&quot;card&quot;) Card card, @JsonProperty(&quot;amount&quot;) Amount amount) {
 this.card = card;
 this.amount = amount;
 }

 public Card getCard() {
 return card;
 }

 public Amount getAmount() {
 return amount;
 }
}
</code></pre>

blocks|key|2257053|text|通过添加@NoArgsConstructor，它将解决这个问题。因为如果我们没有提供任何构造函数，编译器就会添加默认的构造函数，但是如果我们添加了任何参数化的构造函数，而忽略了添加NoArgsConstructor，那么我们就会得到这个异常。我们应该强制添加默认的构造函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2257054|entityMap^0|4|I|2I|H|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

by adding <code>@NoArgsConstructor</code> , it will fix the issue.
Because compiler will add the default constructor if we have not provided any constructor, but if we have added any parameterized constructor and missed to add <code>NoArgsConstructor</code> we will get this exception. We should compulsorily add the default Constructor.

blocks|key|519625|text|我在用Lombok。我得到了错误，因为我没有将@NoArgsConstructor放在我的模型类中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519626|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I'm using Lombok. I got the error because I did not put @NoArgsConstructor in my model class.

blocks|key|2256619|text|只想指出这个回答提供了一个更好的解释。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2256620|基本上你可以把@Getter和@NoArgConstructor放在一起|style|CODE|2256621|或者让Lombok使用@ConstructorProperties文件重新生成lombok.config，|2256622|或者用-parameters标志编译java项目，|2256623|或者让杰克逊使用Lombok的@Builder|2256624|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/51465038/8529009^0|6|2|0|0|7|7|F|H|0|B|M|13|D|0|3|B|0|F|8|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|6|7|Z|8|@$A|10|B|11|F|G]|$A|12|B|13|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|14|8|@$A|15|B|16|F|G]|$A|17|B|18|F|G]]|9|@]|C|$]]|$1|J|3|K|5|6|7|19|8|@$A|1A|B|1B|F|G]]|9|@]|C|$]]|$1|L|3|M|5|6|7|1C|8|@$A|1D|B|1E|F|G]]|9|@]|C|$]]|$1|N|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]]|O|$P|$5|Q|R|S|C|$T|U]]]]

Just want to point out that this <a href="https://stackoverflow.com/a/51465038/8529009">answer</a> provides a better explanation. 
Basically you can either have <code>@Getter</code> and <code>@NoArgConstructor</code> together 
or let Lombok regenerates <code>@ConstructorProperties</code> using <code>lombok.config</code> file, 
or compile your java project with <code>-parameters</code> flags, 
or let Jackson use Lombok's <code>@Builder</code>

blocks|key|2256731|text|如果你在使用LOMBOK。如果没有lombok.config文件，则创建一个文件并添加这一行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2256732|lombok.anyconstructor.addconstructorproperties=true|code-block|syntax|javascript|2256733|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are using LOMBOK.
Create a file lombok.config if you don't have one and add this line.
<pre><code>lombok.anyconstructor.addconstructorproperties=true
</code></pre>

blocks|key|1414446|text|如果使用pojo添加@NoArgsConstructor+@AllArgsConstructor，则在类OR中添加构造函数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1414447|还包括JsonProperty+-+@JsonProperty("name")+private+List<Employee>+name;|offset|length|style|CODE|1414448|entityMap^0|0|I|1E|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Add Constructor in class
OR
if you are using pojo add
@NoArgsConstructor
@AllArgsConstructor
Also include JsonProperty -
<code>@JsonProperty(&quot;name&quot;) private List&lt;Employee&gt; name;</code>

blocks|key|520662|text|如果您使用尤内斯特作为http库，那么使用GsonObjectMapper而不是JacksonObjectMapper也可以。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|520663|
<dependency>
++++<groupId>com.konghq</groupId>
++++<artifactId>unirest-object-mappers-gson</artifactId>
++++<version>2.3.17</version>
</dependency>|code-block|syntax|javascript|520664|Unirest.config().objectMapper+=+GsonObjectMapper()|520665|entityMap|0|LINK|mutability|MUTABLE|url|http://kong.github.io/unirest-java/#responses^0|L|G|14|J|5|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

If you are using <a href="http://kong.github.io/unirest-java/#responses" rel="nofollow noreferrer">Unirest</a> as the http library, using the <code>GsonObjectMapper</code> instead of the <code>JacksonObjectMapper</code> will also work.

<pre class="lang-xml prettyprint-override"><code>&lt;!-- https://mvnrepository.com/artifact/com.konghq/unirest-object-mappers-gson --&gt;
&lt;dependency&gt;
 &lt;groupId&gt;com.konghq&lt;/groupId&gt;
 &lt;artifactId&gt;unirest-object-mappers-gson&lt;/artifactId&gt;
 &lt;version&gt;2.3.17&lt;/version&gt;
&lt;/dependency&gt;
</code></pre>

<pre><code>Unirest.config().objectMapper = GsonObjectMapper()
</code></pre>

blocks|key|519350|text|当您使用Lombok构建器时，您将得到上述错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|519351|+@JsonDeserialize(builder+=+StationResponse.StationResponseBuilder.class)
+public+class+StationResponse{
+++//define+required+properties+
+}+++++

+@JsonIgnoreProperties(ignoreUnknown+=+true)
+@JsonPOJOBuilder(withPrefix+=+"")
+public+static+class+StationResponseBuilder+{}|code-block|syntax|javascript|519352|参考资料：https://projectlombok.org/features/Builder+With+Jackson|offset|length|519353|entityMap|0|LINK|mutability|MUTABLE|url|https://projectlombok.org/features/Builder^0|0|0|5|16|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

When you are using Lombok builder you will get the above error. 

<pre><code> @JsonDeserialize(builder = StationResponse.StationResponseBuilder.class)
 public class StationResponse{
 //define required properties 
 } 

 @JsonIgnoreProperties(ignoreUnknown = true)
 @JsonPOJOBuilder(withPrefix = "")
 public static class StationResponseBuilder {}
</code></pre>

Reference : <a href="https://projectlombok.org/features/Builder" rel="nofollow noreferrer">https://projectlombok.org/features/Builder</a> With Jackson

blocks|key|2256581|text|我可以通过@JacksonProperty注释在Kotlin中解决这个问题。以上情况的使用示例如下：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2256582|import+com.fasterxml.jackson.annotation.JsonProperty
...
data+class+Station(
+++++@JacksonProperty("repsol_id")+val+repsol_id:+String,
+++++@JacksonProperty("name")+val+name:+String,
...|code-block|syntax|javascript|2256583|entityMap^0|5|G|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

I could resolve this problem in Kotlin with help of <code>@JacksonProperty</code> annotation. Usage example for above case would be:

<pre><code>import com.fasterxml.jackson.annotation.JsonProperty
...
data class Station(
 @JacksonProperty("repsol_id") val repsol_id: String,
 @JacksonProperty("name") val name: String,
...
</code></pre>

blocks|key|520824|text|我的问题原因对我来说似乎很少见，不确定是否有其他人在相同的条件下得到了错误，我发现原因是对以前的提交进行了区分，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|520825|通过我的build.gradle，我使用了以下2种编译器选项，并注释掉了这一行，解决了这个问题|520826|//compileJava.options.compilerArgs+=+['-Xlint:unchecked','-Xlint:deprecation']|code-block|syntax|javascript|520827|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

My cause of issue seems very uncommon to me, not sure if anybody else gets the error under same condition, I found the cause by diffing previous commits, here you go :
Via my build.gradle I was using these 2 compiler options, and commenting out this line fixed the issue
<pre class="lang-java prettyprint-override"><code>//compileJava.options.compilerArgs = ['-Xlint:unchecked','-Xlint:deprecation']
</code></pre>

blocks|key|1414332|text|在下面的Usecase中遇到了同样的错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1414333|我尝试使用sprint+(2.0.0快照版本)访问其余的(Put映射)端点，而没有在各自的bean中使用默认的构造函数。|offset|length|style|BOLD|1414334|但是，对于最新的Spring版本(2.4.1版本)，相同的代码正在正常工作。|1414335|因此，bean默认构造函数是，在Spring的最新版本中不再需要。|1414336|entityMap^0|0|D|9|1G|3|0|H|7|0|E|I|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@$D|P|E|Q|F|G]|$D|R|E|S|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|W|8|@$D|X|E|Y|F|G]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|M|$]]

Encountered the same error in below Usecase.
I tried to hit the Rest(Put mapping) end point using sprint boot(2.0.0 Snapshot Version) without having default constructor in respective bean.
But with latest Spring Boot versions(2.4.1 Version) the same piece of code is working without error.
so the bean default constructor is no longer needed in latest version of Spring Boot

blocks|key|519511|text|我得到了同样的错误，问题是我的模型没有实现可序列化的，所以也要检查这一点，因为这也是的原因之一。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|519512|entityMap^0|L|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

I got the same error and the problem was that my model didn't implement Serializable, so check this as well, might help since this is also one of the reason.

blocks|key|2257029|text|我在科特林也遇到了例外。如果您在应用KotlinModule后仍然有问题，您可能(虽然不太可能)在某个地方有值类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2257030|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I also faced the exception in Kotlin. If you're still having problem after applying KotlinModule, you might (though not quite probably) have value class somewhere.

blocks|key|520990|text|我补充我的答案，因为我自己，由于我的疏忽，遇到了这个错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|520991|通过导入一个静态对象意外地引入了错误的序列化程序，并且很长一段时间都无法理解原因是什么。也许这能帮到别人。|520992|//+Wrong+serializer+via+static+object+import
import+static+org.keycloak.util.JsonSerialization.mapper;|code-block|syntax|javascript|520993|注意。|520994|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I'm adding my answer, because I myself, due to my inattention, encountered this error.
Accidentally introduced the wrong serializer through the import of a static object and for a long time could not understand what was the reason. Maybe this will help someone else.
<pre><code>// Wrong serializer via static object import
import static org.keycloak.util.JsonSerialization.mapper;
</code></pre>
Be careful.

blocks|key|2257080|text|在我的例子中，这个问题只发生在构建类型发行版中，原因是“\dto”文件夹中的一些类被蒙蔽了，其中包含存根。为了解决这个问题，我在pro卫士规则文件中添加了以下规则：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2257081|-keep+public+class+com.your.app_package.dto.**+{+*;+}

-keep+@**annotation**+class+*+{*;}

#Preserve+JacksonXml+(PUBLIC_ONLY+crash+fix)
-keepattributes+*Annotation*,EnclosingMethod,Signature
-keepnames+class+com.fasterxml.jackson.**+{+*;+}
-dontwarn+com.fasterxml.jackson.databind.**
-keep+class+org.codehaus.**+{+*;+}
-keepclassmembers+public+final+enum+com.fasterxml.jackson.annotation.JsonAutoDetect$Visibility+{
++++public+static+final+com.fasterxml.jackson.annotation.JsonAutoDetect$Visibility+*;+}|code-block|syntax|javascript|2257082|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In my case the problem occurred only in the build type release and was due to the obscuring of some classes in the '\dto' folder which contains the stubs.
To solve I added the following rules in the proguard-rules.pro file:
<pre><code>-keep public class com.your.app_package.dto.** { *; }

-keep @**annotation** class * {*;}

#Preserve JacksonXml (PUBLIC_ONLY crash fix)
-keepattributes *Annotation*,EnclosingMethod,Signature
-keepnames class com.fasterxml.jackson.** { *; }
-dontwarn com.fasterxml.jackson.databind.**
-keep class org.codehaus.** { *; }
-keepclassmembers public final enum com.fasterxml.jackson.annotation.JsonAutoDetect$Visibility {
 public static final com.fasterxml.jackson.annotation.JsonAutoDetect$Visibility *; }
</code></pre>

I am trying to consume an API using Retrofit and Jackson to deserialize. I am getting the onFailure error <code>No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator</code>.

No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

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我正在尝试使用一个API，使用Retrofit和Jackson反序列化。我正在得到onFailure错误No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator。

问与默认构造一样，没有任何创建者存在)：无法从对象值反序列化(没有委托或基于属性的Creator )。
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回答 31

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问与默认构造一样，没有任何创建者存在)：无法从对象值反序列化(没有委托或基于属性的Creator )。EN

回答 31

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问与默认构造一样，没有任何创建者存在)：无法从对象值反序列化(没有委托或基于属性的Creator )。
EN