This repo contains the answer of Android Dry Run Interview under Udacity Android Nanodegree Program

Android has lot of good libraries, like retrofit, volley, butterknife and many more. I liked Retrofit, as it converts rest API into interface, making network calls clean as well as robust. Also, it uses Gson by default, so, there is no need to do any custom parsing, allowing us to focus on business logic.

To open other app from our app requires intent. These are the steps involved:

1. I have to create Map URI,
2. Then ask intent service to open the URI in the app, which has already registered to open such kind of URI. So, if google maps is installed, it will open the URI in the map, otherwise it will open the URI in the browser.
3. Start the intent. Here is the sample code:

    String uri = "http://maps.google.co.in/maps?q=" + yourAddress;
    Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
    context.startActivity(intent);

Here is the solution:

public class StringCompression {    
    public static String compresString(String text) {
        int length = text.length();
        /*
        *  Compression makes sense at length of larger than or equal to 3.
        *  For instance: "aaa" -> "a3"
        */
        if(length > 2) {
            String compressedText = "";	
            char lastChar = text.charAt(0);	
            int charCount = 1;
            for(int i = 1; i < length; i++) {
                if(text.charAt(i) == lastChar) charCount++;	
                else {
                    compressedText += Character.toString(lastChar) + Integer.toString(charCount);
                    lastChar = text.charAt(i);	
                    charCount = 1;
                }
            }	
            compressedText += Character.toString(lastChar) + Integer.toString(charCount);
            if(compressedText.length() < length)
                return compressedText;		
        }		return text;
    }
}

Please find the gist here.

Options to store data: a) Shared Preferences b) Internal Storage c) External Storage d) Sqlite database (For data not saving on phone, we can use external APIs)

Shared preferences are useful for storing the primitive data types like integer, boolean and also String. In onCreate() method, we can create the shared preference, and add it to the Shared Preference database. We can add values with methods such as putInt(), putBoolean() and putString(). If at any point, we have to change the preference, we just open the Preference Editor using SharedPreferences.Editor, and just start editing it. Also, we can get the instance at any point of time.

For complex data types, we should use remaining methods.

Fragments are a powerful feature of the Android platform and are slightly complex. It makes it easy to reuse our views, be it tablet or phone. I like fragments as they ease out the android development process, taking care of various views we have to support. In the case of tablets, we can use a single activity and attach two fragments to it, one for showing the list or grid and the other for the detail.

I would like to learn the internals of android libraries and design patterns, and build very robust and cool apps.
I would also like to contribute to open source being part of great android community.