Gson StackOverflow on JSONWriter - json

Question

I created a system and it libero access via Webservice Restful, with him I release a maintenance list, this list is formed by objects: Cliente, Endereco, Manutencao, StatusManutencao.
I have a class that seeks the bench all maintenance that is Class: PesquisaManutencoesWebService, and the class that receives the call webservice calls SimpleRestService.
When I turn my maintenance list in JSON (return gson.toJson (ws.getJson ());), is generated the following error:
java.lang.StackOverflowError
java.io.StringWriter.write (StringWriter.java:112)
com.google.gson.stream.JsonWriter.string (JsonWriter.java:559)
com.google.gson.stream.JsonWriter.writeDeferredName (JsonWriter.java:402)
com.google.gson.stream.JsonWriter.value (JsonWriter.java:495)
com.google.gson.internal.bind.TypeAdapters $ 8.write (TypeAdapters.java:268)
Already tested if the list is working, and really is, I can get all the data I want, but I just can not turn into JSON.
Can anyone help me? Thanks.
Class Cliente
#Entity
#Table(name = "cliente")
public class Cliente implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue
private Long id;
#NotBlank #Size(max = 6)
#Column(nullable = false, length = 6)
private String codigoAcesso;
#NotBlank #Size(max = 100)
#Column(nullable = false, length = 100)
private String nome;
#Size(max = 150)
#Column(nullable = true, length = 150)
private String email;
#NotBlank #Size(max = 14)
#Column(name = "doc_receita_federal", nullable = false, length = 14)
private String documentoReceitaFederal;
#Enumerated(EnumType.STRING)
#Column(nullable = false, length = 15)
private TipoPessoa tipo;
#OneToMany(mappedBy = "cliente", cascade = CascadeType.ALL)
private List<Endereco> enderecos = new ArrayList<>();
Class Endereco
#Entity
#Table(name = "endereco")
public class Endereco implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue
private Long id;
#NotBlank #Size(max = 150)
#Column(nullable = false, length = 150)
private String logradouro;
#NotBlank #Size(max = 20)
#Column(nullable = false, length = 20)
private String numero;
#Size(max = 100)
#Column(length = 100)
private String complemento;
#NotBlank #Size(max = 100)
#Column(nullable = false, length = 100)
private String cidade;
#NotBlank #Size(max = 100)
#Column(nullable = false, length = 100)
private String uf;
#NotBlank #Size(max = 8)
#Column(nullable = false, length = 8)
private String cep;
//#NotBlank
#ManyToOne
#JoinColumn(name = "cliente_id", nullable = false)
private Cliente cliente;
getters and setters ...
Class Manutencao
#Entity
#Table(name = "manutencao")
public class Manutencao implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue
private Long id;
#ManyToOne
#JoinColumn(name = "cliente_id")
private Cliente cliente;
#Embedded
private StatusManutencao status;
#NotBlank
#Column(nullable = false, length = 255, name="descricao_manutencao")
private String descricaoManutencao;
#Column(name = "valor", precision = 10, scale = 2)
private BigDecimal valor;
getters and setters ...
Class StatusManutencao
#Embeddable
public class StatusManutencao implements Serializable {
private static final long serialVersionUID = 1L;
#Column(name="recebido")
#Type(type="true_false")
private boolean recebido;
#Temporal(TemporalType.DATE)
#Column(name="data_recebimento")
private Date dataRecebimento;
#Column(name="em_manutencao")
#Type(type="true_false")
private boolean emManutencao;
#Temporal(TemporalType.DATE)
#Column(name="data_manutencao")
private Date dataManutencao;
#Column(name="manutencao_finalizada")
#Type(type="true_false")
private boolean manutencaoFinalizada;
#Temporal(TemporalType.DATE)
#Column(name="data_finalizacao")
private Date dataFinalizacao;
#Column(name="entregue")
#Type(type="true_false")
private boolean entregue;
#Temporal(TemporalType.DATE)
#Column(name="data_entrega")
private Date dataEntrega;
#Column(name="pago")
#Type(type="true_false")
private boolean pago;
#Temporal(TemporalType.DATE)
#Column(name="data_pagamento")
private Date dataPagamento;
getters and setters ...
Class PesquisaManutencaoWebService
public class PesquisaManutencoesWebService implements Serializable {
private static final long serialVersionUID = 1L;
private EntityManager manager;
private EntityManagerFactory factory;
private EntityTransaction trx;
public PesquisaManutencoesWebService(){
this.factory = Persistence.createEntityManagerFactory("ManutencaoPU");
this.manager = factory.createEntityManager();
this.trx = manager.getTransaction();
this.trx.begin();
}
#SuppressWarnings("unchecked")
public JsonModel getJson(){
List<Manutencao> manutencoes = manager.createQuery("SELECT m FROM Manutencao m").getResultList();
return new JsonModel(manutencoes);
}
}
Class SimpleRestService
#Path("service")
public class SimpleRestService {
private PesquisaManutencoesWebService ws;
#GET
#Produces("application/json")
#Path("/{codigoAcesso}/")
public String getManutencoes(#PathParam("codigoAcesso") String codigoAcesso) throws IOException, SQLException, ClassNotFoundException{
ws = new PesquisaManutencoesWebService();
Gson gson = new GsonBuilder().serializeSpecialFloatingPointValues().setPrettyPrinting().create();
return gson.toJson(ws.getJson());
}
}

Answer 1

In most of the cases StackOverError is thrown when call stack exceeds because of excessive deep or infinite recursion. It is also thrown when the need to store the local variable in the method exceeds the allocated stack size.
In your Endereco Class, add Fetch Type to #ManyToOne anotattion in the Cliente attribute, then your code should look like this:
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "cliente_id")
private Cliente cliente;
When you set FetchType to Lazy, you are basically saying that Entity should not be nested to the parent Entity.
Then try to get the Clientes List Manually...