Friday, 14 November 2014

Convert JSON data to Java Object


“com.google.gson.Gson” class provides fromJson() method to convert JSON to java object.

public class Organization {
    private String name;
    private float yrsOfExperience;

    Organization(String name, float yrsOfExperience){
        this.name = name;
        this.yrsOfExperience = yrsOfExperience;
    }

    public String getName() {
        return name;
    }

    public float getYrsOfExperience() {
        return yrsOfExperience;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setYrsOfExperience(float yrsOfExperience) {
        this.yrsOfExperience = yrsOfExperience;
    }
    
}

import java.util.*;

public class Employee {
    private List<Organization> org = new ArrayList<Organization> ();
    private String firstName;
    private String lastName;
    private double salary;

    Employee(String firstName, String lastName, double salary, List<Organization> org){
        this.firstName = firstName;
        this.lastName = lastName;
        this.salary = salary;
        this.org = org;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public List<Organization> getOrg() {
        return org;
    }

    public double getSalary() {
        return salary;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public void setOrg(List<Organization> org) {
        this.org = org;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }
    
}

import java.util.*;
import com.google.gson.Gson;

public class JsonToJava {
    public static void main(String args[]){
        List<Organization> organizations = new ArrayList<Organization> ();
        Organization o1 = new Organization("Honeywell", 2.2f);
        Organization o2 = new Organization("IBM", 1.8f);
        organizations.add(o1);
        organizations.add(o2);

        Employee emp = new Employee("Krishna", "Hari", 80000, organizations);

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

        System.out.println(json);

        Employee emp1 = gson.fromJson(json, Employee.class);
        System.out.println(emp.getFirstName());
        System.out.println(emp.getLastName());
        System.out.println(emp.getSalary());

        Iterator<Organization> iter = emp1.getOrg().iterator();
        while(iter.hasNext()){
            Organization org = iter.next();
            System.out.println(org.getName() +" " +org.getYrsOfExperience());
        }
    }
}


Output
{"org":[{"name":"Honeywell","yrsOfExperience":2.2},{"name":"IBM","yrsOfExperience":1.8}],"firstName":"Krishna","lastName":"Hari","salary":80000.0}
Krishna
Hari
80000.0
Honeywell 2.2
IBM 1.8


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