Iterating through json objects received from the server

Question

I have a large group of json objects received from web server. I want to get all the data from all the json objects. For that How do I iterate through the json object so, that a

Answer 1

If you know the structure of your JSON String, then use google's Gson() (add the JAR to your project) to deserialize, in 3 easy steps:

1. Create the Entity class (whatever your object is, I'm giving "Person" as example).

   public class Person {
   @Expose //this is a Gson annotation, tells Gson to serialize/deserialize the element
   @SerializedName("name") //this tells Gson the name of the element as it appears in the JSON     string, so it can be properly mapped in Java class
   private String name;
   @Expose
   @SerializedName("lastName")
   private String lastName;
   @Expose
   @SerializedName("streetName")
   private String streetName;
   //getters and setters follow
   }
   

2. Create the class into which you deserialize the JSON string. In my example, the JSON string is actually an array of Persons.

   public class PersonsList extends ArrayList<Person> implements Serializable{
   //nothing else here
   }
   
   If the JSON string has a named key, then you don't have to extend ArrayList:
   
   public class PersonsList implements Serializable{
   @Expose
   @SerializedName("persons")
   private ArrayList<Person> persons;
   //getters / setters
   }
   

3. Do the actual deserialization:

   String json = "[{person1},{person2},{person3}]";//your json here
   Gson gson = new Gson();
   PersonsList personsList = gson.fromJson(json, PersonsList.class);
   //then, depending on how you build PersonsList class, you iterate:
   for(Person p : personsList)//if you extended ArrayList
   //or
   for(Person p : personsList.getPersons())//if it's the second option
   

Answer 2

You could use Gson and parse the string to a java object.

For example you have a class.

public class Location{

    private String name;

    private String city;

    //getters and setters

}

and in your class you could just parse it to Location class

Gson gson=new Gson();

Location[] locations=gson.fromJson(jsonString,Location[].class);

after that you could loop through the locations

for(int i=0;i<locations.length;i++){

     System.out.println(locations[i].getName());

}

if you need to separate the city from the name

ArrayList name=new ArrayList();
ArrayList city=new ArrayList();

for(int i=0;i<locations.length;i++){

   name.add(locations[i].getName());
    city.add(locations[i].getCity());

}