Java 12 to Java 16 features

Java 12 to Java 16 brought steady improvements, refining features and introducing new enhancements. Let’s break it down:

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Java 12 Features (Released March 2019)

1. Switch Expressions (Preview)
   • Allowed switch to return a value in a more concise way:

     var result = switch (day) {
         case MONDAY, FRIDAY -> "Busy day!";
         case SATURDAY, SUNDAY -> "Weekend!";
         default -> "Regular day.";
     };
     

   • Improves readability and eliminates repetitive break statements.
2. Improved Garbage Collection
   • Introduced Shenandoah GC, reducing pause times for large heaps.
   • Enhanced performance in memory management.
3. Compact Number Formatting
   • Helps format numbers in a human-readable way:

     NumberFormat formatter = NumberFormat.getCompactNumberInstance(Locale.US, NumberFormat.Style.SHORT);
     System.out.println(formatter.format(1000)); // Outputs "1K"
     

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Java 13 Features (Released September 2019)

1. Text Blocks (Preview)
   • Enables easier multiline string handling:

     String json = """
         {
             "name": "Java",
             "version": 13
         }
         """;
     

   • Improves readability and reduces escape sequences.
2. Enhancements to Switch Expressions
   • Further refinement of switch case for clearer structure.

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Java 14 Features (Released March 2020)

1. Records (Preview)
   • Introduced a simpler way to create immutable data carriers:

     record Person(String name, int age) {}
     

   • Reduces boilerplate code in POJOs.
2. Pattern Matching for instanceof (Preview)
   • Eliminates redundant casting:

     if (obj instanceof String str) {
         System.out.println(str.length());
     }
     

3. Helpful NullPointerException Messages
   • Improves debugging by clearly indicating what was null.

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Java 15 Features (Released September 2020)

1. Text Blocks (Final)
   • Multiline strings were finalized after previews in Java 13 & 14.
2. Sealed Classes (Preview)
   • Restricts inheritance to specific subclasses:

     public sealed class Animal permits Dog, Cat {}
     

3. Hidden Classes
   • Allows creating runtime classes that aren’t visible outside their defining class loader.

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Java 16 Features (Released March 2021)

1. Records (Final)
   • Records became a permanent part of Java.
2. Pattern Matching for instanceof (Final)
   • Officially part of the language after preview versions.
3. Improved Stream API
   • Added toList() method for easier list conversion:

     Stream<String> stream = Stream.of("A", "B", "C");
     List<String> list = stream.toList();
     

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Java 12 to 16 focused on refining usability, improving syntax, and optimizing performance.