I'm trying to print some JSONObjects from a JSONArray in JAVA using the MVC pattern and the json.simple library, but when I run it the program just print the last JSONObject.
This is my Main class:
package Main;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import Controlador.Controlador;
import Vista.Vista;
import Modelo.Modelo;
public class Main {
private static String ID;
public static void main(String[] args) throws IOException, InterruptedException {
Modelo modelo = llenarDatosModelo();
Vista vista = new Vista();
//se crea un objeto controlador y se le pasa el modelo y la vista
Controlador controlador = new Controlador(modelo, vista);
// se muestra los datos
controlador.actualizarVista();
}
//método estático que retorna el autor con sus datos
private static Modelo llenarDatosModelo() {
JSONParser jsonParser = new JSONParser ();
try(FileReader reader = new FileReader ("datos.json")) {
JSONObject documento = (JSONObject) jsonParser.parse(reader);
JSONObject resultados = (JSONObject)documento.get("search-results");
JSONArray Entrys = (JSONArray) resultados.get("entry");
for(Object Entry: Entrys) {
mostrarInformacionEntry ((JSONObject) Entry);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ParseException e) {
e.printStackTrace();
}
Modelo autor = new Modelo();
autor.setID(ID);
return autor;
}
private static void mostrarInformacionEntry(JSONObject entry) {
ID = (String) entry.get("dc:identifier");
}
This is my model:
package Modelo;
public class Modelo {
private String ID;
private String url;
private String eid;
private String document_count;
private String cited_by_count;
private String citation_count;
private String affiliation;
private String give_name;
private String classification;
private String publication_start;
private String publication_end;
public Modelo() {
}
public String getID() {
return ID;
}
public void setID(String string) {
this.ID = string;
}
public String geturl() {
return url;
}
public void seturl(String url) {
this.url = url;
}
public String geteid() {
return eid;
}
public void seteid(String eid) {
this.eid = eid;
}
public String getdocument_count() {
return document_count;
}
public void setdocument_count(String document_count) {
this.document_count = document_count;
}
public String getcited_by_count() {
return cited_by_count;
}
public void setcited_by_count(String cited_by_count) {
this.cited_by_count = cited_by_count;
}
public String getcitation_count() {
return citation_count;
}
public void setcitation_count(String citation_count) {
this.citation_count = citation_count;
}
public String getaffiliation() {
return affiliation;
}
public void setaffiliation(String affiliation) {
this.affiliation = affiliation;
}
public String getgive_name() {
return give_name;
}
public void setgive_name(String give_name) {
this.give_name = give_name;
}
public String getclassification() {
return classification;
}
public void setclassification(String classification) {
this.classification = classification;
}
public String getpublication_start() {
return publication_start;
}
public void setpublication_start(String publication_start) {
this.publication_start = publication_start;
}
public String getpublication_end() {
return publication_end;
}
public void setpublication_end(String publication_end) {
this.publication_end = publication_end;
}
}
This is my View:
package Vista;
public class Vista {
public void imprimirDatos(String string,String url, String eid, String document_count, String cited_by_count, String citation_count, String affiliation, String give_name, String classification, String publication_start, String publication_end) {
System.out.println("\n****AUTOR****");
System.out.println("ID: " string);
System.out.println("url: " url);
System.out.println("eid: " eid);
System.out.println("document_count: " document_count);
System.out.println("cited_by_count: " cited_by_count);
System.out.println("citation_count: " citation_count);
System.out.println("affiliation: " affiliation);
System.out.println("give_name: " give_name);
System.out.println("classification: " classification);
System.out.println("publication_start: " publication_start);
System.out.println("publication_end: " publication_end);
}
}
And this is my controller:
package Controlador;
import Modelo.Modelo;
import Vista.Vista;
public class Controlador {
//objetos vista y modelo
private Vista vista;
private Modelo modelo;
//constructor para inicializar el modelo y la vista
public Controlador(Modelo modelo, Vista vista) {
this.modelo = modelo;
this.vista = vista;
}
//getters y setters para el modelo
public String getID() {
return modelo.getID();
}
public void setID(String ID) {
this.modelo.setID(ID);
}
public String geturl() {
return modelo.geturl();
}
public void seturl(String url) {
this.modelo.seturl(url);
}
public String geteid() {
return modelo.geteid();
}
public void seteid(String eid) {
this.modelo.seteid(eid);
}
public String getdocument_count() {
return modelo.getdocument_count();
}
public void setdocument_count(String document_count) {
this.modelo.setdocument_count(document_count);
}
public String getcited_by_count() {
return modelo.getcited_by_count();
}
public void setcited_by_count(String cited_by_count) {
this.modelo.setcited_by_count(cited_by_count);
}
public String getcitation_count() {
return modelo.getcitation_count();
}
public void setcitation_count(String citation_count) {
this.modelo.setcitation_count(citation_count);
}
public String getaffiliation() {
return modelo.getaffiliation();
}
public void setaffiliation(String affiliation) {
this.modelo.setaffiliation(affiliation );
}
public String getgive_name() {
return modelo.getgive_name();
}
public void setgive_name(String give_name) {
this.modelo.setgive_name(give_name);
}
public String getclassification() {
return modelo.getclassification();
}
public void setclassification(String classification) {
this.modelo.setclassification(classification);
}
public String getpublication_start() {
return modelo.getpublication_start();
}
public void setpublication_start(String publication_start) {
this.modelo.setpublication_start(publication_start);
}
public String getpublication_end() {
return modelo.getpublication_end();
}
public void setpublication_end(String publication_end) {
this.modelo.setpublication_end(publication_end);
}
//pasa el modelo a la vista para presentar los datos
public void actualizarVista() {
vista.imprimirDatos(modelo.getID(),modelo.geturl(), modelo.geteid(), modelo.getdocument_count(), modelo.getcited_by_count(), modelo.getcitation_count(), modelo.getaffiliation(), modelo.getgive_name(), modelo.getclassification(), modelo.getpublication_start(), modelo.getpublication_end());
}
}
When I run it the console shows this:
****AUTOR****
ID: SCOPUS_ID:85137292444
url: null
eid: null
document_count: null
cited_by_count: null
citation_count: null
affiliation: null
The JSONArray Entrys have multiple articles, I want the program to print them all. Does anyone know what I'm doing wrong?
The JSON File is:
https://drive.google.com/file/d/1t53qiU64eJVUupDA-Ie2ZR1Xakz7npGI/view?usp=sharing
CodePudding user response：
Your method mostrarInformacionEntry is reading the fields of one JSON array entry. Your problem is, that this method isn't creating a new model per entry. Instead it assigns the read value dc:identifier to the class variable ID. This is done for all entries in the array. An entry overwrites the saved ID of the previous entry. At the end you create a model with the ID of the last loaded entry. But you should create a model for each entry.
You need a custom entry class/POJO:
public class ModeloEntry {
private String ID;
private String url;
private String eid;
private String document_count;
private String cited_by_count;
private String citation_count;
private String affiliation;
private String give_name;
private String classification;
private String publication_start;
private String publication_end;
public ModeloEntry() {
}
public String getID() {
return ID;
}
public void setID(String string) {
this.ID = string;
}
public String geturl() {
return url;
}
public void seturl(String url) {
this.url = url;
}
public String geteid() {
return eid;
}
public void seteid(String eid) {
this.eid = eid;
}
public String getdocument_count() {
return document_count;
}
public void setdocument_count(String document_count) {
this.document_count = document_count;
}
public String getcited_by_count() {
return cited_by_count;
}
public void setcited_by_count(String cited_by_count) {
this.cited_by_count = cited_by_count;
}
public String getcitation_count() {
return citation_count;
}
public void setcitation_count(String citation_count) {
this.citation_count = citation_count;
}
public String getaffiliation() {
return affiliation;
}
public void setaffiliation(String affiliation) {
this.affiliation = affiliation;
}
public String getgive_name() {
return give_name;
}
public void setgive_name(String give_name) {
this.give_name = give_name;
}
public String getclassification() {
return classification;
}
public void setclassification(String classification) {
this.classification = classification;
}
public String getpublication_start() {
return publication_start;
}
public void setpublication_start(String publication_start) {
this.publication_start = publication_start;
}
public String getpublication_end() {
return publication_end;
}
public void setpublication_end(String publication_end) {
this.publication_end = publication_end;
}
}
And you need a model in the context of MVC, holding all entries:
public class Modelo {
private List<ModeloEntry> entries = new ArrayList<>();
public void addEntry(ModeloEntry entry) {
this.entries.add(entry);
}
public List<ModeloEntry> getEntries() {
return entries;
}
}
Then you can do the following:
public class Main() {
// ...
private static Modelo llenarDatosModelo() {
Modelo autor = new Modelo(); // Create the MVC model first
JSONParser jsonParser = new JSONParser ();
try(FileReader reader = new FileReader ("datos.json")) {
JSONObject documento = (JSONObject) jsonParser.parse(reader);
JSONObject resultados = (JSONObject)documento.get("search-results");
JSONArray Entrys = (JSONArray) resultados.get("entry");
for(Object Entry: Entrys) {
ModeloEntry entry = mostrarInformacionEntry ((JSONObject) Entry); // Create a entry instance per JSON array entry
author.addEntry(entry); // Add the entry to your MVC model
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ParseException e) {
e.printStackTrace();
}
return autor; // Return your MVC model
}
private static ModeloEntry mostrarInformacionEntry(JSONObject entry) {
ModeloEntry entry = new ModeloEntry(); // Create a entry instance
entry.setId((String) entry.get("dc:identifier"));
return entry;
}
}
Your for-each loop is then outsourced to your controller class:
public class Controlador {
private Vista vista;
private Modelo modelo;
public void actualizarVista() {
// Print each entry of your MVC model line by line
for(ModeloEntry entry : modelo.getEntries()) {
vista.imprimirDatos(modelo.getID(),modelo.geturl(), modelo.geteid(), modelo.getdocument_count(), modelo.getcited_by_count(), modelo.getcitation_count(), modelo.getaffiliation(), modelo.getgive_name(), modelo.getclassification(), modelo.getpublication_start(), modelo.getpublication_end());
}
}
}