Get Started with Android SDK

This guide will help you get started with Contentstack Android SDK to build apps powered by Contentstack.

Prerequisites

To get started with Android SDK, you will need the following:

Android Studio or Eclipse.
SDK version 7.0 or later

SDK Installation and Setup

To integrate your Android project with Contentstack, install the following dependency:

Gradle

implementation 'com.contentstack.sdk:android:{latest_version}'

Maven

<dependency>
  <groupid>com.contentstack.sdk</groupid>
  <artifactid>android</artifactid>
  <version>{latest_version}</version>
</dependency>

You can find the latest version of dependency here.

Initialize SDK

Contentstack offers three regions (North America (NA), Europe (EU) and Azure North America (NA) as data centers to store customers' account details and data. These regions are independent of each other and therefore have a dedicated set of instructions to use SDKs offered by Contentstack.

To use SDKs for the Europe and Azure NA region, you will have to make certain changes in the configuration of the SDK, as detailed below, and the rest of the instructions remain the same.

To initialize the SDK, specify application context, stack’s API Key, delivery token, and name of the environment where will publish your content, as shown in the snippet below:

Stack stack = Contentstack.stack(context, "stack_api_key", "delivery_token", "environment_name");

Note: By default, the SDK uses the North American region. Configuration changes are not required for North American region users.

For Europe or Azure North America, check the code of your region and configure your SDK.

Once you have initialized the SDK, you can query entries to fetch the required content.

For Setting the branch for Europe or Azure North America, check the code of your region and initialize SDK in a particular branch.

Cache Policies

The cache policies allow you to define the source from where the SDK will retrieve the content. Based on the selected policy, the SDK can get the data from cache, network, or both.

Let’s look at the various cache policies available for use:

POLICIES	DESCRIPTION
NETWORK_ONLY (default)	If you set NETWORK_ONLY as the cache policy, the SDK retrieves data through a network call, and saves the retrieved data in the cache. This is set as the default policy.
CACHE_ELSE_NETWORK	If you set CACHE_ELSE_NETWORK as the cache policy, the SDK gets data from the cache. However, if it fails to retrieve data from the cache, it makes a network call.
NETWORK_ELSE_CACHE	If you set NETWORK_ELSE_CACHE as the cache policy, the SDK gets data using a network call. However, if the call fails, it retrieves data from cache.
CACHE_ONLY	If you set CACHE_ONLY as the cache policy, the SDK gets data from the cache.
CACHE_THEN_NETWORK	If you set CACHE_THEN_NETWORK as the cache policy, the SDK gets data from cache, and then makes a network call. (A success callback will be invoked twice.)
IGNORE_CACHE	If you set IGNORE_CACHE as the cache policy, the SDK always retrieves data by making a network call, without maintaining any cache.

You can set a cache policy on an entry, an asset, and/or a query object.

Setting a cache policy on an entry

To set the cache policy to all the query objects of an entry, refer to the code below:

public void entry_NETWORK_ONLY() {
    final Entry entry = stack.contentType("user").entry("blt11c1ad111ff1ddc1");
    entry.setCachePolicy(CachePolicy.NETWORK_ONLY);
    entry.addParam("key", "some_value");
    entry.fetch(new EntryResultCallBack() {
        @Override
        public void onCompletion(ResponseType responseType, Error error) {
            if (error == null) {
                //Success block
            } else {
                //Error block
            }
        }
    });
}

Setting a cache policy on an asset

To set the cache policy to all the query objects of an asset, refer to the code below:

public void assets_NETWORK_ONLY() {
    stack.assetLibrary().setCachePolicy(CachePolicy.NETWORK_ONLY);
    stack.assetLibrary().fetchAll(new FetchAssetsCallback() {
        @Override
        public void onCompletion(ResponseType responseType, List < Asset > assets, Error error) {
            if (error == null) {
                // Success block
            } else {
                // Failure block
            }
        }
    });
}

Setting a cache policy on a query object

To set/override a cache policy on a specific query object, refer to the code below:

public void query_NETWORK_ONLY() {
    Query query = stack.contentType("categories").query();
    query.where("uid", "blt11c1ad111ff1ddc1");
    query.setCachePolicy(CachePolicy.NETWORK_ONLY);
    query.find(new QueryResultsCallBack() {
        @Override
        public void onCompletion(ResponseType responseType, QueryResult queryresult, Error error) {
            if (error == null) {
                // Success block
            } else {
                // Failure block
            }
        }
    });
}

Basic Queries

Contentstack SDKs let you interact with the Content Delivery APIs and retrieve content from Contentstack. They are read-only in nature. The SDKs fetch and deliver content from the nearest server via Fastly, our powerful and robust CDN.

Get a Single Entry

To retrieve a single entry from a content type use the code snippet given below:

ContentType contentType = stack.contentType("content_type_uid");
Entry blogEntry = contentType.entry("entry_uid");
blogEntry.fetch(new EntryResultCallBack() {
    @Override
    public void onCompletion(ResponseType responseType, Error error) {
        if (error == null) {
            // Success block
        } else {
            // Error block  
        }
    }
});

Get Multiple Entries

To retrieve multiple entries of a particular content type, use the code snippet given below:

//stack is an instance of Stack class
Query blogQuery = stack.contentType("content_type_uid").query();
blogQuery.find(new QueryResultsCallBack() {
    @Override
    public void onCompletion(ResponseType responseType, QueryResult queryResult, Error error) {
        if(error == null){
            //Success block
        }else{
            //Error block
        }
    }
});

These were examples of some of the basic queries of the SDK. For advanced queries, refer to Contentstack Android SDK API reference.

Note: Currently, the Android SDK does not support multiple content types referencing in a single query. For more information on how to query entries and assets, refer the Queries section of our Content Delivery API documentation.

Paginating Responses

In a single instance, the Get Multiple Entries query will retrieve only the first 100 items of the specified content type. You can paginate and retrieve the rest of the items in batches using the skip and limit parameters in subsequent requests.

Stack stack = Contentstack.stack(context, "api_key", "delivery_token", "environment", false);
Query csQuery = stack.contentType("contentType_name").query();
csQuery.skip(20);
csQuery.limit(20);
csQuery.find(new QueryResultsCallBack() {

          @Override
          public void onCompletion(ResponseType responseType, QueryResult queryResult, Error error) {


          }
      });

Limitations

We have a URL size limitation of 8KB on API Requests that hit our CDN services. Any Request URL that goes above this size limit will receive the 400 - Bad request error response. Please make sure you limit the size of your API Requests.
The Android SDK does not support multiple content types referencing in a single query.
Currently, the Android SDK does not yet support querying Global Field schemas (All Global Fields and Single Global Field). You can include these details when querying content type details (All Content Types and Single Content Type) with the include_global_field_schema query parameter.