Gain insights into developing Android apps using Java, Groovy, and XML. Discover hands-on, project-based learning while building a fully functional Travel Blog Application for your portfolio.

So, you want to learn to build your own Android apps? You’ve come to the right place.

In this course, you’ll take a hands-on, project-based approach to developing Android applications. You’ll work with the most common tools that Android developers use every day including Java, Groovy, and XML. As you learn, you’ll build a fully functional Travel Blog Application that will be a great addition to your portfolio.

By the end of this course, you’ll have built a fully functional Android application and be ready to build even more complex projects.

Modern Android App Development with Java

### Preferences

One of the most common ways to persist data on the Android phone is to use [SharedPreferences](https://developer.android.com/training/data-storage/shared-preferences).

The shared preference is basically a key-value store solution for a small amount of data with a built-in memory cache. We already used shared preferences to persist the login state.

### Files

When the data is too big for the shared preference, we can always use plain old files.

```
String filename = "myfile";
String fileContents = "Hello world!";
try (FileOutputStream fos = context.openFileOutput(filename, Context.MODE_PRIVATE)) {
    fos.write(fileContents.toByteArray());
}

```

The problem with files is that we need to convert our data to a format that can be stored and reconstructed later, such as a JSON string, which is not efficient in some cases.

### SQLite

Fortunately, in *Android* we can create a local database - *SQLite*. 

The `android.database.sqlite` package contains all sorts of API to work with databases - from simple queries to complicated joins. While the *Android* *SQLite* package contains everything we need, the API is pretty basic and requires us to write a lot of boilerplate code. For these reasons, Google decided to write an abstraction on top of `android.database.sqlite` package to make it easier to work with a database.

This layer is available as a separate library called *Room*. In this chapter we are going to learn how to use the *Room* database to store and access blog articles.

# Preferences

One of the most common ways to persist data on the Android phone is to use [SharedPreferences](https://developer.android.com/training/data-storage/shared-preferences).

The shared preference is basically a key-value store solution for a small amount of data with a built-in memory cache. We already used shared preferences to persist the login state.

# Files

When the data is too big for the shared preference, we can always use plain old files.

```
String filename = "myfile";
String fileContents = "Hello world!";
try (FileOutputStream fos = context.openFileOutput(filename, Context.MODE_PRIVATE)) {
    fos.write(fileContents.toByteArray());
}

```

The problem with files is that we need to convert our data to a format that can be stored and reconstructed later, such as a JSON string, which is not efficient in some cases.

# SQLite

Fortunately, in *Android* we can create a local database - *SQLite*. 

The `android.database.sqlite` package contains all sorts of API to work with databases - from simple queries to complicated joins. While the *Android* *SQLite* package contains everything we need, the API is pretty basic and requires us to write a lot of boilerplate code. For these reasons, Google decided to write an abstraction on top of `android.database.sqlite` package to make it easier to work with a database.

This layer is available as a separate library called *Room*. In this chapter we are going to learn how to use the *Room* database to store and access blog articles.

In this chapter, we will improve user experience by implementing offline support, so when we launch the application, the blog list screen must immediately show cached data.

This lesson explains the different options available on Android to cache the data for offline support.

Android Ecosystem

Hello World

Travel Blog - Login Screen

Travel Blog - Details Screen

Travel Blog - List Screen

Travel Blog - Search & Sort

Travel Blog - Offline

Conclusion

Caching Solutions

Preferences #