Warm greetings! This lesson introduces data streams, which are essentially continuous datasets. Imagine a weather station or a gaming application gathering data every second — both generate data streams! We will learn how to handle these data streams using Java by accessing individual elements, slicing segments, and converting these streams into strings for easier handling.

In Java, data streams can be represented using collections such as ArrayList and Map. We will use a class to encapsulate operations related to these data streams in our Java application. Let's consider a simple Java class named DataStream:

To use this, we create a sample data stream as an instance of our DataStream class, where each element is a map with key-value pairs:

To look into individual elements of a data stream, we use zero-based indexing. The get method we introduce below fetches the i-th element from the data stream:

Here's how we can use the get method:

In essence, stream.get(2) fetches us the map with { "id": 3, "value": 300 }.

To fetch a range of elements, we can use slicing. Java offers methods like subList in ArrayList to achieve this. Here's how you might implement a slice method:

Here's a quick usage example:

For better readability, we may want to convert our data streams into strings. In Java, we can utilize libraries like Gson to achieve this. Below is an example of implementing the toString method:

To demonstrate:

In this lesson, we explored data streams and how to represent and manipulate them using Java collections like ArrayList. We crafted a class that encapsulates operations on data streams in Java, including accessing elements, slicing ranges, and converting streams to string representations.

Now it's time to apply your newfound knowledge in the practice exercises that follow!