Thursday, September 4, 2014

Getting Started with Dropbox Core API for Android

Dropbox has several APIs listed on their developer portal, and that can be a little confusing at first. Take your time to poke through each one, and find out for yourself which one works best for you.

I wanted to learn how to integrate Dropbox functionality into my Android app, so I did a Google search for "dropbox android sdk". The first result led me to the download page for the Android SDK for the Core API, and at that point not knowing that there were multiple SDKs for the different APIs, I decided to start with that.

This article will focus specifically on getting the starter project for the Core API set up in Eclipse/ADT.

1. Download the Android SDK for Core API. Click on the download link on the download page.

2. Unzip the downloaded SDK, then import the sample project.

3. If you try running the project now, you see this:

So go to the site and register your app to obtain the app key and app secret. Just go to and click on "App Console" on the left hand navigation pane.

Sign into your Dropbox account to continue, and you'll see this: 

Click on the Create app button on the top left corner of the page as shown in the screenshot above. You'll get a form and you'll have to also verify your email address when you create the app if you haven't done so already. Select Dropbox API app as shown below:

Fill out the rest of the form:

As you see in the screenshot above, you can't use the word "Dropbox" in the app name - the branding guidelines tell you that you can't do that. Once you successfully create an app, you get a dashboard similar to the one below. Find the app key and app secret, and copy and paste it into the right file in Eclipse.

4. Next, try running the project again. You see this:

It means we also need to change the manifest file of the app to include the app key. As you can see in the following screenshot, you replace "CHANGE_ME" with your app key in the line highlighted:

5. Run the project now. It should work! You'll see this:

Clicking on "Link with Dropbox" as seen in the screenshot above would prompt you (and anyone who uses this app) to sign in with Dropbox:

After going through the sign-in flow and granting permission for the app to access the files and folders in your Dropbox, the app brings you back to the main view. You can click on "New Photo" to upload a photo, and see a progress bar of it uploading. Clicking on "Roulette" will display a photo that was uploaded onto Dropbox.

That's it! It was super painless and easy to set up the starter project for the Dropbox Core API Android SDK .

Monday, September 1, 2014

Picasso Library

Ever wondered if there were an Android library that'd handle displaying photos for you in a beautiful grid, and most importantly, display it quickly?

I've been using Picasso by Square in a couple of my projects since the beginning of the year and I really like it.

One single line of code is all it takes to load an image hassle-free into your application:

It is super speedy and you can load images not only from the web, but also from resources like R.drawable.yourimage and files like new File(...). But most importantly, it does all the heavy lifting for you so you just have to focus on writing your application code. Picasso takes care of caching, loading only the images you'd see, image compression, and all that good stuff.

Let's walk through how to set up the starter project that Square provides along with the Picasso library.

Install by downloading the .jar from - click the red button under "Download" as shown in the screenshot below.

Let's set up the sample project from the GitHub repository and see the library in action for ourselves.

Once you import it into Eclipse as an Android Application Project, you should create a folder called "libs" and paste the picasso jar file from the step above into it.

Let's work on solving the import errors that comes with this sample code:

Really, it's annoying to have to deal with import errors every time you add a library. In this case, adding the Android Support Library will solve some of the problems.

But this doesn't solve everything; you've got to solve the rest of the import errors manually. 

Whenever you have errors with R, it means your resources folder ("res") has problems. Sure enough, it says that there is "no resource found that matches the given name: attr 'android:fontFamily'".

This is because android:fontFamily is only available to API level 16 and above. There are two solutions:

1. Check your API level, and target your build to API level 16 and above. Do this by right clicking on the project in the Package Explore view, going to Properties, and selecting Android.

You can easily see which API level you are currently compiling against, and you can change this to something above API level 16 by using the checkboxes.

2. Simply remove all references to android:fontFamily. For example, remove that line with the error in the code above. This is only a UI change to make the font pretty, and we can do without it. Go through the rest of the layout files and remove any such references. 

Notice that the sample_widget_info.xml file has similar problems as well. We get a similar error message: "error: No resource identifier found for attribute 'widgetCategory' in package 

Again, this is because widget is not supported below API level 17, so you either remove widgets from the sample, or you target API level 17 and above.

If you choose to target a lower API level and delete the widget functionality, you have to make changes in other files as well, such as AndroidManifest.xml. Delete the segment below:

It's worth it because your library can now be used to target older versions of Android. Because of the fragmentation of the Android OS, a lot of people use older versions of Android and you don't want to limit your audience just because of a functionality in a library you used that may not turn out to be essential anyway.

Also delete and comb through the .java files, removing any Widget functionality.

This should resolve all the errors and you can run the sample app on your device or an emulator to see the Picasso library in action. Prepared to be amazed by how blazingly fast it is :)

Friday, August 29, 2014

Great Slide Deck: Ten Reasons Developers Hate Your API

When designing an API, it's important to follow several well-intentioned and reasonable principles. Check out this slide deck for a great overview of the different principles you should adhere to when developing an API! It covers everything from documentation to how you expose different services to how you communicate updates and version changes.

Tuesday, August 26, 2014

Android + Drive: Getting Started with Google Drive on Android

Google makes it so easy to integrate the Drive API into Android.

Firstly, Google Drive has been part of Android for some time now. That means you don't have to download any additional SDK since all you need is the Google Play Services library that comes bundled with every Eclipse/ADT installation.

1) Set up the Google Play Services project as a library in your Eclipse workspace (for a breakdown of the steps involved, see this guide), and add it to the Google Drive Quickstart Android application (download it here)

2) Create a new project in the Google Developers Console.

3) We are interested in giving our app access to our users' folders and files on Google Drive, so we need to enable OAuth.

Once your project from Step 2 has been created, go to Credentials and click "Create new client ID."

4) Select "Installed Application", select "Android" and then enter the package name as well as the signing certificate fingerprint.

For Debugging:

Open your console, and type in the following command:

keytool -exportcert -alias androiddebugkey -keystore path-to-debug-or-production-keystore -list -v

Copy the SHA1 key and paste it into the Google Developers Console.

For Production:

Before you can enter these though, you'll need to go back to Eclipse/ADT and sign your app. Select the project, then click on File > Export. Select Export Android Application, and then select the project you want to sign. Create a new keystore and then create a new key as shown in the images below.

Export the package as an .apk file:

You should see the SHA1 after you complete this process. If you don't see it or missed it, don't worry, just go through the same process again (using existing keystore/key instead of creating a new one) and you'll see it on the final screen. Copy the SHA1 and paste it into the Google Developers Console. Also enter your package name (e.g. com.example.drivedemo) into the appropriate field.

You should see the Client ID on the page after you submit the required information.

To read more on what you just did, click here.

5) Make sure you go into Google Developers Console and turn on access to the Drive API under your project (select your project, click on "APIs and auth" in the left naviation pane, and then select "APIs"). Note that there are two things: Drive API and Drive SDK. Earlier, I kept getting an error that looked like this:

Ultimately I realized that this was because I'd turned on Drive SDK, but not Drive API. So to save yourself some hassle, just turn both on.

6) Also put in your email address and product name in "Consent Screen" under "APIs and Auth". Apparently if you don't do that it won't work - there are lots of posts on forums about this.

7) Run the application (right click on the project > run as > android application) and it should work! It will prompt you to select a Google account on your phone, and then ask you to grant consent to the app. Finally you'll be able to take photos using your phone and upload them to Google Drive.

And that's it! You have gotten Google Drive working on Android.

Thursday, August 21, 2014

Installing Eclipse/ADT for Android Development

Android is big. It has already been big for several years, and it looks like its on a path to complete domination, so if you don't already know how to program on Android, you should start learning pretty soon.

In this post I'll talk about how to set up your development environment for Android.

What's the difference between Java and Android?

According to Wikipedia,

There is no Java Virtual Machine in the Android platform. Java bytecode is not executed. Instead Java classes are compiled into a proprietary bytecode format and run on Dalvik, a specialized virtual machine (VM) designed specifically for Android. 

There is a lot of confusion between what's Java and what's Android. For now, think of Java as a programming language, and think of Android as an Operating System. (Of course, the distinctions are not as clear-cut as that) To run apps on Android, you write them in Java.

If you want to get deeper into the nitty-gritty of the differences, check out this article by CNET which does a pretty good job explaining the differences and how they were the subject of a recent lawsuit by Oracle against Google.

Installation and Set-up for Windows

1. Download Eclipse ADT with Android SDK for Windows here. You'll realize that there are two full-featured IDEs you can use for Android development, Eclipse ADT and Android Studio. Android Studio is still in beta so I'd recommend the former. I haven't yet tried Android Studio, but after reading this post on the differences between Android Studio and Eclipse I just might.

Question: What's the difference between Eclipse and Eclipse ADT?

Eclipse is an open-source IDE, mostly provided in Java. Eclipse ADT is developed by Google and is a plug-in for Eclipse specifically designed for Android development.

2. Unzip the downloaded file and launch Eclipse from adt-bundle-<os-platform>/eclipse/

Having problems unzipping the file using the default unzipping tool in Windows? That's because the tool doesn't work when the file path is too long. Move the zipped file to the root of C:/ before trying again, and the problem should be fixed.

3. Just click OK when the prompt on selecting your workspace appears. Awesome! You're in Eclipse and can start writing Android apps right away!

Node.js & Express

I was first exposed to Node.js during the HackNY hackathon, one of the largest student hackathons on the East Coast. My partner and I built an awesome news/media consumption web app that basically calls into about 10 APIs whenever you enter a search query, then returns a page aggregating results from all those sources. It was lots of fun and a surefire way to win a prize at the hackathon, and we won a prize for using the most number of APIs.

I needed a refresher on Node.js because I haven't touched it since, so I went and re-educated myself on the good stuff recently by reading some getting started guides and following along to create simple, barebones apps. Here are some links I found useful:

The dead-simple step-by-step guide for front-end developers to getting up and running with Node.js, Express, Jade and MongoDB - this one's written by someone who develops on Windows. So if you're always left scratching your head when someone writes about some tool that's only available on Mac, this one's for you. This combination of Node.js, Express, Jade and MongoDB is one of those modern stacks that the industry is increasingly using nowadays.

Creating a simple RESTful web app with Node.js, Express, and MongoDB - by the same author above.

The Node Beginner Book - I don't think this one's worth its $9.99 price. But for free, you get pretty much the first 1/3 of the book on that page I linked to and it does a good job covering the basics.