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I'm trying to use Jackson to read/write my POJOs to/from Json. As of right now, I've got it configured and working for my classes, except for a 3rd party class. When trying to read in the Json I get the error:
org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type After a few quick google searches, it appears that my class needs either a default constructor or to override the default constructor with annotations. Unfortunately, the class in which this is failing is from a 3rd party library and that class does not have a default constructor and I obviously cannot over-write the code.
So my question is, is there anything I can do about this or am I just out of luck?
Thanks.
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Jackson uses default (no argument) constructor to create object and then sets value using setters. so you only need @NoArgsConstructor and @Setter.
Jackson won't use a constructor with arguments by default, you'd need to tell it to do so with the @JsonCreator annotation. By default it tries to use the no-args constructor which isn't present in your class.
What is the default constructor? Java doesn't require a constructor when we create a class. However, it's important to know what happens under the hood when no constructors are explicitly defined. The compiler automatically provides a public no-argument constructor for any class without constructors.
The compiler automatically provides a no-argument, default constructor for any class without constructors. This default constructor will call the no-argument constructor of the superclass.
There are two commonly used Jackson annotations to ignore properties, which are @JsonIgnore and @JsonIgnoreProperties. The former is directly applied to type members, telling Jackson to ignore the corresponding property when serializing or deserializing.
By default, Jackson recreates data objects by using no-arg constructors. This is inconvenient in some cases, such as when a class has non-default constructors and users have to write no-arg ones just to satisfy Jackson's requirements.
Public Constructor Let's consider the Employee class structure. It has two required fields: id and name, thus we define a public all-arguments constructor that has a set of arguments that matches the set of object’s fields: This way, we’ll have all the object’s fields initialized at the moment of creation.
For Jackson 2, you can add the mix-in directly to the objectMapper, objectMapper.addMixInAnnotations (target, mixinSource) ( source) He is right, I used the mixin approach to deserialized a field of the type android.location.Location, which by the way does not have a default constructor (and I have not control over the class/3rd party).
You could make use of Jackson's Mix-Ins feature, coupled with the Creator feature. The Mix-Ins feature alleviates the need to annotate the original third-party code, and the Creator feature provides a mechanism for custom instance creation.
For yet more customization, it's not too involved to write a custom deserializer.
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