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Design Patterns and Best Practices in Java

You're reading from   Design Patterns and Best Practices in Java A comprehensive guide to building smart and reusable code in Java

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Product type Paperback
Published in Jun 2018
Publisher Packt
ISBN-13 9781786463593
Length 280 pages
Edition 1st Edition
Languages
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Authors (4):
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Kamalmeet Singh Kamalmeet Singh
Author Profile Icon Kamalmeet Singh
Kamalmeet Singh
Lucian-Paul Torje Lucian-Paul Torje
Author Profile Icon Lucian-Paul Torje
Lucian-Paul Torje
Sumith Kumar Puri Sumith Kumar Puri
Author Profile Icon Sumith Kumar Puri
Sumith Kumar Puri
Adrian Ianculescu Adrian Ianculescu
Author Profile Icon Adrian Ianculescu
Adrian Ianculescu
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Toc

Table of Contents (11) Chapters Close

Preface 1. From Object-Oriented to Functional Programming FREE CHAPTER 2. Creational Patterns 3. Behavioral Patterns 4. Structural Patterns 5. Functional Patterns 6. Let's Get Reactive 7. Reactive Design Patterns 8. Trends in Application Architecture 9. Best Practices in Java 10. Other Books You May Enjoy

Error handling


The Observables contain a couple of operators that allow error handling, swallowing exceptions, transforming exceptions, call-finally blocks, retrying the failed sequence, and disposing resources even if an error occurs.

The catch operator

These operators enable recovering from errors by continuing the sequence:

  • onErrorResumeNext: Instructs an Observable to pass control to another Observable given by a supplier, instead of invoking onError when something goes wrong
  • onErrorReturn: Instructs an Observable to emit a default supplied by a function, in case of error
  • onErrorReturnItem: Instructs an Observable to emit a supplied default, in case of error
  • onExceptionResumeNext: Instructs an Observable to pass control to another Observable instead of invoking onError in case something goes wrong

The following example shows how to use the onErrorReturnItem method; calling it without the flatMap trick will stop the flow and output Default at the end. By deferring the call to the exception...

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