Convert realm object to json

realmobject_to_json.java

import org.json.JSONException;
import org.json.JSONObject;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;

import io.realm.RealmObject;

/**
 * Convert realm object to json
 * Author: Eduardo Sales
 * Date: Nov, 10 2021
 */
public class RealmJsonAdapter {

    public JSONObject toJson(Class<? extends RealmObject> modelClass, Object realmObject, ArrayList<String> fieldsIgnored, Boolean snakeCase) {

        JSONObject jsonObject = new JSONObject();
        boolean ignore = fieldsIgnored != null && fieldsIgnored.size() > 0;
        ArrayList<String> fields = this.getFieldNames(modelClass);

        try {
            for (String fieldName : fields)
            {
                if (this.isConstant(fieldName)) {
                    continue;
                }

                if (ignore && fieldsIgnored.contains(fieldName)) {
                    continue;
                }

                String methodName = "get"+ this.strCapital(fieldName);

                Method method = modelClass.getMethod(methodName);

                String jsonName = (snakeCase ? this.strSnake(fieldName) : fieldName);

                jsonObject.put(
                        jsonName,
                        method.invoke(realmObject)
                );
            }
        } catch (JSONException
                | NoSuchMethodException
                | InvocationTargetException
                | IllegalAccessException e) {
            e.printStackTrace();
        }

        return jsonObject;
    }

    /** get property names of a class **/
    private ArrayList<String> getFieldNames(Class<? extends RealmObject> modelClass) {
        ArrayList<String> fields = new ArrayList<>();
        for (Field f: modelClass.getDeclaredFields()) {
            fields.add(f.getName());
        }
        return fields;
    }

    /** capitalize string **/
    private String strCapital(String str) {
        String retStr = str;
        try {
            // We can face index out of bound exception if the string is null
            retStr = str.substring(0, 1).toUpperCase() + str.substring(1);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return retStr;
    }

    /** convert string to snake_case **/
    private String strSnake(final String camelStr) {
        StringBuilder stringBuilder = new StringBuilder();
        for (char c : camelStr.toCharArray()) {
            if (Character.isUpperCase(c)) {
                stringBuilder.append('_').append(c);
            } else {
                stringBuilder.append(c);
            }
        }

        return stringBuilder.toString().toLowerCase();
    }

    /** check if string is a model constant **/
    private boolean isConstant(String s) {
        for (char c : s.toCharArray()) {
            if (c == '_') {
                continue;
            }

            if(! Character.isUpperCase(c)) {
                return false;
            }
        }

        return true;
    }
}