Скачать или смотреть How to Dynamically Chain RxJava Observables and Pass Values Between Them

Discover a solution to dynamically chain `RxJava` observables using a builder design pattern while passing values between them effectively.
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How to Dynamically Chain RxJava Observables and Pass Values Between Them

Problem Introduction

If you're working with RxJava and need to dynamically chain observables, you're likely aware that doing this in a static manner often limits flexibility. In the scenario presented, we start with a basic setup where the observables are linked in a predetermined sequence, but the real challenge arises when we need to manage multiple fallback adapters based on conditions evaluated at runtime. Specifically, the goal is to pass the connectivity state (i.e., whether isConnected is true or false) from one adapter to the next in a dynamic list of fallback adapters.

The Initial Setup

Let's break down the original method of chaining observables:

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In this example, we initiate a connection and use concatMap to sequentially apply fallback adapters after a delay. The problem arises because this chain is static, and we want to modify it at runtime.

The Proposed Solution

To achieve dynamic chaining of observables while passing the connectivity state, an effective method is to use a builder pattern. This allows us to construct our observable chain flexibly. Below are the primary steps to achieve this.

Step 1: Create a Builder Class

We start by defining a DisposableBuilder class. This class is responsible for constructing the observable chain dynamically.

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Step 2: Append Adapters Dynamically

The append method is designed to add new adapters to the observable chain. For each adapter, the method concatenates it with a delay to prevent rapid succession of calls.

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Step 3: Retrieve the Observable

Finally, we can retrieve the constructed observable to subscribe to it:

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Step 4: Utilizing the Builder

To use this builder in your main code, instantiate it and build the sequence using the given IP address as shown below:

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Conclusion

By implementing this builder pattern, we now have a flexible and dynamic way to chain observables in RxJava without losing the ability to pass relevant states between adapters. This method not only improves readability and maintainability but also allows for robust handling of various connection states throughout the process.

With this approach, you can be confident that your application can adapt to changing conditions while still leveraging the power of reactive programming in Java.