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Java 11 and 12 ??? New Features

You're reading from   Java 11 and 12 ??? New Features Learn about Project Amber and the latest developments in the Java language and platform

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Product type Paperback
Published in Mar 2019
Publisher Packt
ISBN-13 9781789133271
Length 242 pages
Edition 1st Edition
Languages
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Author (1):
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Mala Gupta Mala Gupta
Author Profile Icon Mala Gupta
Mala Gupta
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Table of Contents (23) Chapters Close

Preface 1. Section 1: JDK 10 FREE CHAPTER
2. Type Inference 3. AppCDS 4. Garbage Collector Optimizations 5. Miscellaneous Improvements in JDK 10 6. Section 2: JDK 11
7. Local Variable Syntax for Lambda Parameters 8. Epsilon GC 9. The HTTP Client API 10. ZGC 11. Flight Recorder and Mission Control 12. Miscellaneous Improvements in JDK 11 13. Section 3: JDK 12
14. Switch Expressions 15. Miscellaneous Improvements in JDK 12 16. Section 4: Project Amber
17. Enhanced Enums in Project Amber 18. Data Classes and Their Usage 19. Raw String Literals 20. Lambda Leftovers 21. Pattern Matching 22. Other Books You May Enjoy

Memory pressure testing with Epsilon

Imagine that you don't want your application, or say, a section of your application, to use more than a certain amount of heap memory, such as 40 MB. How can you assert this? In this case, you can configure to execute your applications with -Xmx40m. Here's some example code that adds the same string values as the key/value pair to HashMap and then removes it—by iterating it multiple times (1_000_000 to be precise):

import java.util.*; 
class EpMap { 
    public static void main(String args[]) { 
        Map<String, String> myMap = new HashMap<String, String>(); 
        int size = 1_000_000; 
        for(int i = 0; i < size; i++) { 
            String java = new String("Java"); 
            String eJavaGuru = new String("eJavaGuru.com"); 
            myMap.put(java, eJavaGuru); 
         ...
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