Android converting an object to JSON format with GSON not working

Question

I am trying to convert an object to a JSON format using GSON. I will then send the JSON to the webservice written in php. Unfortunately for some reason, the method gson.toJson(object) is not working.

I have this java object - intervention (This contains several fields of types String, Date, Time and bitmaps). When I try to do this:

Gson gson = new Gson();
String json = gson.toJson(intervention);

I get this in the gson variable:

gson={serializeNulls:falsefactories:[Factory[type=com.google.gson.JsonElement,adapter=com.google.gson.internal.bind.TypeAdapters$25@40fbe5c8], com.google.gson.internal.bind.ObjectTypeAdapter$1@411b7db8, Factory[type=java.lang.String,adapter=com.google.gson.internal.bind.TypeAdapters$13@40ff42d0], Factory[type=java.lang.Integer+int,adapter=com.google.gson.internal.bind.TypeAdapters$7@411c00f8], Factory[type=java.lang.Boolean+boolean,adapter=com.google.gson.internal.bind.TypeAdapters$3@411b4798], Factory[type=java.lang.Byte+byte,adapter=com.google.gson.internal.bind.TypeAdapters$5@4122dbd0], Factory[type=java.lang.Short+short,adapter=com.google.gson.internal.bind.TypeAdapters$6@4122a0c8], Factory[type=java.lang.Long+long,adapter=com.google.gson.internal.bind.TypeAdapters$8@40fc5d98], Factory[type=java.lang.Double+double,adapter=com.google.gson.Gson$4@412295f0], Factory[type=java.lang.Float+float,adapter=com.google.gson.Gson$5@41229898], Factory[type=java.lang.Number,adapter=com.google.gson.internal.bind.TypeAdapters$11@41223618], Factory[type=java.lang.Character+char,adapter=com.google.gson.internal.bind.TypeAdapters$12@41224168], Factory[type=java.lang.StringBuilder,adapter=com.google.gson.internal.bind.TypeAdapters$16@411a7550], Factory[type=java.lang.StringBuffer,adapter=com.google.gson.internal.bind.TypeAdapters$17@411a7790], Factory[type=java.math.BigDecimal,adapter=com.google.gson.internal.bind.TypeAdapters$14@40ff4568], Factory[type=java.math.BigInteger,adapter=com.google.gson.internal.bind.TypeAdapters$15@411b4440], Factory[type=java.net.URL,adapter=com.google.gson.internal.bind.TypeAdapters$18@411be338], Factory[type=java.net.URI,adapter=com.google.gson.internal.bind.TypeAdapters$19@41229028], Factory[type=java.util.UUID,adapter=com.google.gson.internal.bind.TypeAdapters$21@411a2200], Factory[type=java.util.Locale,adapter=com.google.gson.internal.bind.TypeAdapters$24@411a2510], Factory[typeHierarchy=java.net.InetAddress,adapter=com.google.gson.internal.bind.TypeAdapters$20@41229328], Factory[type=java.util.BitSet,adapter=com.google.gson.internal.bind.TypeAdapters$2@411ca140], com.google.gson.internal.bind.DateTypeAdapter$1@412024f8, Factory[type=java.util.Calendar+java.util.GregorianCalendar,adapter=com.google.gson.internal.bind.TypeAdapters$23@411bef70], com.google.gson.internal.bind.TimeTypeAdapter$1@41229920, com.google.gson.internal.bind.SqlDateTypeAdapter$1@411b67c0, com.google.gson.internal.bind.TypeAdapters$22@411a2500, com.google.gson.internal.bind.ArrayTypeAdapter$1@41222e90, com.google.gson.internal.bind.TypeAdapters$26@411b7ca0, Factory[type=java.lang.Class,adapter=com.google.gson.internal.bind.TypeAdapters$1@4121d940], com.google.gson.internal.Excluder@4122a3c8, com.google.gson.internal.bind.CollectionTypeAdapterFactory@40ff26d0, com.google.gson.internal.bind.MapTypeAdapterFactory@40ff2980, com.google.gson.internal.bind.ReflectiveTypeAdapterFactory@40ff2ba0],instanceCreators:{}}

import android.graphics.Bitmap;
import com.google.gson.annotations.SerializedName;
import java.util.Date;

public class Intervention{

@SerializedName("case_id")
private String case_id;
public String getCase_id() {
    return case_id;
}

@SerializedName("user_id")
private String user_id;
public String getUser_id() {
    return user_id;
}

@SerializedName("account_id")
private String account_id;
public String getAccount_id() {
    return account_id;
}

@SerializedName("description")
private String description;
public String getDescription() {
    return description;
}

@SerializedName("solution")
private String solution;
public String getSolution() {
    return solution;
}

@SerializedName("status")
private String status;
public String getStatus() {
    return status;
}

@SerializedName("user_remarks")
private String user_remarks;
public String getUser_remarks() {
    return user_remarks;
}


@SerializedName("customer_remarks")
private String customer_remarks;
public String getCustomer_remarks() {
    return customer_remarks;
}

@SerializedName("case_complete")
private boolean case_complete;
public boolean isCase_complete() {
    return case_complete;
}

@SerializedName("charge_transport")
private boolean charge_transport;
public boolean isCharge_transport() {
    return charge_transport;
}

@SerializedName("service_billable")
private boolean service_billable;
public boolean isService_billable() {
    return service_billable;
}

@SerializedName("date_created")
private Date date_created;
public Date getDate_created() {
    return date_created;
}

@SerializedName("arrival_time")
private String arrival_time;
public String getArrival_time() {
    return arrival_time;
}

@SerializedName("departure_time")
private String departure_time;
public String getDeparture_time() {
    return departure_time;
}

@SerializedName("user_sign")
private Bitmap user_sign;
public Bitmap getUser_sign() {
    return user_sign;
}

@SerializedName("cust_sign")
private Bitmap cust_sign;
public Bitmap getCust_sign() {
    return cust_sign;
}

public void setUser_id(String user_id) {
    this.user_id = user_id;
}

public void setCase_id(String case_id) {
    this.case_id = case_id;
}


public void setAccount_id(String account_id) {
    this.account_id = account_id;
}



public void setDescription(String description) {
    this.description = description;
}



public void setSolution(String solution) {
    this.solution = solution;
}



public void setStatus(String status) {
    this.status = status;
}


public void setUser_remarks(String user_remarks) {
    this.user_remarks = user_remarks;
}



public void setCustomer_remarks(String customer_remarks) {
    this.customer_remarks = customer_remarks;
}



public void setCase_complete(boolean case_complete) {
    this.case_complete = case_complete;
}



public void setCharge_transport(boolean charge_transport) {
    this.charge_transport = charge_transport;
}

public void setService_billable(boolean service_billable) {
    this.service_billable = service_billable;
}


public void setDate_created(Date date_created) {
    this.date_created = date_created;
}

public void setArrival_time(String arrival_time) {
    this.arrival_time = arrival_time;
}


public void setDeparture_time(String departure_time) {
    this.departure_time = departure_time;
}

public void setUser_sign(Bitmap user_sign) {
    this.user_sign = user_sign;
}

public void setCust_sign(Bitmap cust_sign) {
    this.cust_sign = cust_sign;
}

}

The above class is the object class.

I verified the object intervention and the fields are populated. Can someone explain to me what am I doing wrong here?

Answer 1

The current version of Gson (2.2.2) has no problem with Date objects and will serialize/deserialize them just fine. If you are looking for a specific format you can use setDateFormat() in GsonBuilder to specify it.

Your Bitmap object is a different problem. That is a very complex object and not something that Gson is going to know what to do with (never mind very, very difficult to even represent in JSON). You would need to write a custom serializer and deserializer to handle it.

Glancing at the documentation for Bitmap it appears you can extract the pixel data into an int[] array using getPixels() as well as construct a Bitmap from that data using the appropriate static createBitmap() method. You would need to write a serializer that produces JSON from this (and also includes the other parameters) and then a deserializer that would know how to read that JSON and return a Bitmap.

Information on writing custom serializers/deserializers can be found in the Gson User's Guide: https://sites.google.com/site/gson/gson-user-guide#TOC-Custom-Serialization-and-Deserialization