How to map Json to Java classes when some variable names begin with a number?

Question

Recently I've been playing with a webservice that returns a `json` object like this ``` { "id": 88319, "dt": 1345284000, "name": "Benghazi", "coord": { "lat": 32.12, "lon": 20.07 }, "main": { "temp": 306.15, "pressure": 1013, "humidity": 44 }, "wind": { "speed": 1, "deg": -7 }, "clouds": { "all": 90 }, "rain": { "3h": 3 } } ``` I have automatically generated Java classes mapping to that json data. The problem is I cannot generate a Java class with an attribute named 3h (in Java as in many other languages variable identifiers cannot begin with a number). As a hack around I have redefined the attribute 3h as h3, and whenever I receive a json response from the web service I replace the string "3h" by "h3". However, that approach is only appropriate for small projects. I would like to know if there is a more convenient approach to deal with this kind of situation. Notes: For this particular example I used an online tool that generated the java classes given a json example. In other situat…

Accepted Answer

If using Gson you can do it with `@SerializedName` annotation.

Java Class:

```
public class JsonData {

@SerializedName("3h")
    private int h3;

private String name;

public JsonData(int h3, String name) {
        this.h3 = h3;
        this.name = name;
    }

}
```

Serialization: (same class works for fromJson() as well)

```
// prints: {"3h": 3,"name": "Benghazi"}
System.out.println(new Gson().toJson(new JsonData(3, "Benghazi")));
```

Reference: @SerializedName Annotation

How to map Json to Java classes when some variable names begin with a number?

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