Wordpress API - How to loop through a JSON Array of objects in Android/Java

Question

I am new to JSON and I am facing hard time looping through the JSONObjects inside the JSONArray for an Android Application that I am building. I would be thankful if posters would givw a brief explanation of the solution as well because I just don't want to copy & paste the code but understand it. Thank You.

API Link: https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories

API Output:

[
{
    "id": 5580,
    "count": 5,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/diversions/",
    "name": "Diversions",
    "slug": "diversions",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/5580"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=5580"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
},
{
    "id": 9548,
    "count": 5,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/features/",
    "name": "Features",
    "slug": "features",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/9548"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=9548"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
},
{
    "id": 103,
    "count": 10,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/news/",
    "name": "News",
    "slug": "news",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/103"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=103"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
},
{
    "id": 660,
    "count": 10,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/people/",
    "name": "People",
    "slug": "people",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/660"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=660"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
},
{
    "id": 318,
    "count": 10,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/tech/",
    "name": "Tech",
    "slug": "tech",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/318"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=318"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
},
{
    "id": 160479,
    "count": 6,
    "description": "",
    "link": "https://spoketest.wordpress.com/category/traction/",
    "name": "Traction",
    "slug": "traction",
    "taxonomy": "category",
    "parent": 0,
    "meta": [],
    "_links": {
        "self": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories/160479"
            }
        ],
        "collection": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/categories"
            }
        ],
        "about": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/taxonomies/category"
            }
        ],
        "wp:post_type": [
            {
                "href": "https://public-api.wordpress.com/wp/v2/sites/spoketest.wordpress.com/posts?categories=160479"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
}
]

My Code:

import org.json.JSONException;
import org.json.JSONObject;

public class Category {
private int mCategoryID;
private String mCategoryName;

public static Category fromJSON(JSONArray jsonArray) {
    try {
        Category category = new Category();
        category.mCategoryID = jsonArray.getJSONObject("0").getInt("id");
        category.mCategoryName = jsonArray.getJSONObject("0").getString("name");

        return category;
    } catch (JSONException e) {
        e.printStackTrace();
        return null;
    }
}

public int getCategoryID() {
    return mCategoryID;
}

public String getCategoryName() {
    return mCategoryName;
}
}

score 1 · Accepted Answer · answered Jul 24 '17 at 17:03

1

Once you've retrieved the response from the API (using AsyncTask), take the response text and create a JSONArray. Then you can loop through the array and extract the categories.

public void onApiResponse(String response) {
    // Create a JSONArray from the response
    JSONArray jsonArray = new JSONArray(response);

    // Create a structure to store all of the categories
    List<Category> categories = new ArrayList<Category>();

    // Loop through the array and parse all the categories
    for (int i = 0; i < jsonArray.length(); i++) {
        // Extract the JSONObject from the index
        JSONObject jsonCategory = jsonArray.getJSONObject(i);

        // Add the category to the list
        categories.add(Category.fromJSON(jsonCategory));
    }

    // Do something with your categories...
}

EDIT: I see you hardcoded some values into your fromJSON, so I thought I'd post a corrected version of that as well.

public static Category fromJSON(JSONObject jsonObject) {
    try {
        Category category = new Category();
        category.mCategoryID = jsonObject.getInt("id");
        category.mCategoryName = jsonObjectgetString("name");

        return category;
    } catch (JSONException e) {
        e.printStackTrace();
        return null;
    }
}

answered Jul 24 '17 at 17:03

Elan Hamburger

2,137
10
14

I am using James Smith's Android Asynchronous Http Client library for Async related tasks ([link](https://loopj.com/android-async-http/)) and it returns JSONObject. My fromJSON method takes that JSONObject as an input parameter which parses the data. Now in your solution I need a String as an input parameter. Can I covert the JSONObject to String using toString() without any adverse effects? – Jayvijay Gohil Jul 24 '17 at 17:24
The sample response you've posted is a JSON array, not a JSON object. If you're receiving a JSON object in response, the library is not interpreting the response correctly, or you're interpreting the return value incorrectly. Print out the `JSONObject`'s `toString()` and compare to the actual text from the API to see what's going wrong. – Elan Hamburger Jul 24 '17 at 19:24
Oh! I made a mistake. Yes, I get a JSONArray and the input parameter for the fromJSON is JSONArray. But again, can I use toString on the JSONArray without any adverse effect? – Jayvijay Gohil Jul 25 '17 at 00:10
In theory, you should be able to, but that introduces a lot of inefficiency where it could be avoided. Take the time to adapt my answer to your code, don't just copy and paste. – Elan Hamburger Jul 25 '17 at 02:39
OK! Will do. Thank You. – Jayvijay Gohil Jul 25 '17 at 04:41
And I was finally able to implement the code. Thank You. – Jayvijay Gohil Jul 26 '17 at 04:51

Wordpress API - How to loop through a JSON Array of objects in Android/Java

1 Answers1

Linked