Java – if the value in JSON is null, the default value is provided for the property

Suppose I have a class, that is

private class Student {
        private Integer x = 1000;

        public Integer getX() {
            return x;
        }

        public void setX(Integer x) {
            this.x = x;
        }
    }

Now suppose JSON is "{X: 12}" and deserialized, then the value of X is 12 However, if JSON is "{}", then x = 1000 (get is the default value from the attribute, which will be announced in class)

Now, if JSON is "{X: null}", the value of X becomes null, but even in this case, I want the value of X to be 1000 How to do this through Jackson Thank you in advance

I deserialize if it still helps: objectmapper Readvalue (< JSON string here >, student. Class);

Solution

You should be able to override the setter Add @ jsonproperty (value = "X") comments to getters and setters to let Jackson know how to use them:

private class Student {
    private static final Integer DEFAULT_X = 1000;
    private Integer x = DEFAULT_X;

    @JsonProperty(value="x")
    public Integer getX() {
        return x;
    }

    @JsonProperty(value="x")
    public void setX(Integer x) {
        this.x = x == null ? DEFAULT_X : x;
    }
}