HashMap to Java Class Object

Question

On server I have something like this

public class Instrument {
    private String myPropOne;
    private String myPropTwo;
    private String myPropThree;
    public String getMyPropOne() {
        return myPropOne;
    }
    public void setMyPropOne(String myPropOne) {
        this.myPropOne = myPropOne;
    }
    public String getMyPropTwo() {
        return myPropTwo;
    }
public void setMyPropTwo(String myPropTwo) {
    this.myPropTwo = myPropTwo;
}
public String getMyPropThree() {
    return myPropThree;
}
public void setMyPropThree(String myPropThree) {
    this.myPropThree = myPropThree;
    }
}

and on Browser side it a map is to be sent

{ my_prop_one : 'val1', my_prop_two : 'val2', my_prop_three : 'val3'}

One way is to create define toMap() methods and put all the properties one by one and do the same when it is coming from UI-side something like fromMap()

Now question is I want write some common function

set('my_prop_one', 'val2')

so that it will look up the instance and set correct value, i will be extending this class to create more instruments types with different properties I can do this using annotations

public class Instrument {
    private String myPropOne;
    private String myPropTwo;
    private String myPropThree;
    @KeyMap(value="my_prop_one")
    public String getMyPropOne() {
        return myPropOne;
    }
    @KeyMap(value="my_prop_one")
    public void setMyPropOne(String myPropOne) {
        this.myPropOne = myPropOne;
    }
    @KeyMap(value="my_prop_two")
    public String getMyPropTwo() {
        return myPropTwo;
    }
    @KeyMap(value="my_prop_two")
    public void setMyPropTwo(String myPropTwo) {
        this.myPropTwo = myPropTwo;
    }
    @KeyMap(value="my_prop_three")
    public String getMyPropThree() {
        return myPropThree;
    }
    @KeyMap(value="my_prop_three")
    public void setMyPropThree(String myPropThree) {
        this.myPropThree = myPropThree;
    }
}

I will have to write annotations twice. is there any better way to do this? Some thing like I add annotations on properties and getter/setter get somehow linked and can be used to extract properties, some way to create a hashMap?

JsonUtil I am already using gives me this out put

{ myPropOne : 'val1', myPropTwo : 'val2', myPropThree : 'val3'}

But again setter/getter for one property? how to do that? EDIT 3 :

@JsonAnyGetter & @JsonAnySetter

like explained in example here But they work on only map not real properties which is my requirement.

Is it a requirement that you roll your own solution to this? Frameworks like Jackson (github.com/FasterXML/jackson) and Gson (code.google.com/p/google-gson) exist to do this for you. — chut
– chut, Commented May 7, 2014 at 17:19
No there's no such requirement, I am already using JackSon. But how do I make my getter/setter work and mapping of fields? — LNT
– LNT, Commented May 7, 2014 at 17:23

user3655754 · Accepted Answer · 2014-05-20 08:57:20Z

3

Have you tried https://github.com/flori/json-utils? it contains functionalists you are asking for.

answered May 20, 2014 at 8:57

user3655754

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Comments

chut · Accepted Answer · 2014-05-07 18:23:13Z

0

If you're using Jackson (per your comment) then something like this should handle it all for you automatically:

public class Instrument {
    @JsonProperty private String myPropOne;
    @JsonProperty private String myPropTwo;
    ...
}

Then you can use the ObjectMapper class to create your JSON by calling:

Instrument instrument = new Instrument();
instrument.setMyPropOne("val1");
// set other values

ObjectMapper mapper = new ObjectMapper();
// configure mapper if needed
mapper.writeValueAsString(instrument);

answered May 7, 2014 at 18:23

chut

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2 Comments

LNT Over a year ago

Thanks, but I still could not find the answer, because it does not completely solve my problem, i need setter/getters, jackson provides something JsonAnyGetter & JsonAnySetter, but still not what I am looking for. because these work for additional map, not for properties.

chut Over a year ago

One more try, perhaps @JsonValue is what you need? It lets you define a method that returns a Map which is then used instead of fields to create your JSON object. It's sort of like toString() but toJSON() instead. fasterxml.github.io/jackson-annotations/javadoc/2.1.0/com/…

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