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Release Highlights
Java 14

Java 14

Release Information

  • Release Date: March 17, 2020
  • Support Type: Non-LTS (6-month support)
  • End of Support: September 2020 (superseded by Java 15)
  • JEPs: 16 enhancements

Language Features

Switch Expressions (JEP 361) - Standard

Switch expressions became a standard feature after two preview rounds (Java 12, 13).

Before (switch statement):

int numLetters;
switch (day) {
    case MONDAY:
    case FRIDAY:
    case SUNDAY:
        numLetters = 6;
        break;
    case TUESDAY:
        numLetters = 7;
        break;
    case THURSDAY:
    case SATURDAY:
        numLetters = 8;
        break;
    case WEDNESDAY:
        numLetters = 9;
        break;
    default:
        throw new IllegalArgumentException("Invalid day: " + day);
}

After (switch expression):

int numLetters = switch (day) {
    case MONDAY, FRIDAY, SUNDAY -> 6;
    case TUESDAY -> 7;
    case THURSDAY, SATURDAY -> 8;
    case WEDNESDAY -> 9;
};

Benefits:

  • Expressions return values (can assign directly)
  • No fall-through bugs (no break needed)
  • Exhaustiveness checking (compiler ensures all cases handled)
  • Arrow syntax (->) for cleaner code

Pattern Matching for instanceof (JEP 305) - Preview

Simplifies the common pattern of instanceof test followed by cast.

Before:

if (obj instanceof String) {
    String s = (String) obj;
    System.out.println(s.toUpperCase());
}

After:

if (obj instanceof String s) {
    System.out.println(s.toUpperCase());
}

Benefits:

  • Eliminates redundant cast
  • Pattern variable (s) scoped to block
  • Less boilerplate code

Records (JEP 359) - Preview

Records provide compact syntax for immutable data carrier classes.

Before (traditional class):

public final class Point {
    private final int x;
    private final int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int x() { return x; }
    public int y() { return y; }

    @Override
    public boolean equals(Object obj) {
        if (!(obj instanceof Point)) return false;
        Point other = (Point) obj;
        return x == other.x && y == other.y;
    }

    @Override
    public int hashCode() {
        return Objects.hash(x, y);
    }

    @Override
    public String toString() {
        return String.format("Point[x=%d, y=%d]", x, y);
    }
}

After (record):

public record Point(int x, int y) {}

Auto-generated:

  • Constructor
  • Accessors (x(), y())
  • equals(), hashCode(), toString()
  • Final class and fields (immutable)

Use cases: DTOs, value objects, API responses, configuration classes

Text Blocks (JEP 368) - Second Preview

Multi-line string literals with automatic formatting.

Before:

String html = "<html>\n" +
              "    <body>\n" +
              "        <p>Hello, World!</p>\n" +
              "    </body>\n" +
              "</html>\n";

After:

String html = """
    <html>
        <body>
            <p>Hello, World!</p>
        </body>
    </html>
    """;

Benefits:

  • Improved readability for JSON, XML, SQL, HTML
  • No escape sequences for quotes
  • Automatic indentation handling

JVM and Tool Features

Helpful NullPointerExceptions (JEP 358)

Improved NPE messages that pinpoint the exact variable that was null.

Before (Java 13):

Exception in thread "main" java.lang.NullPointerException
    at Main.main(Main.java:5)

After (Java 14):

Exception in thread "main" java.lang.NullPointerException:
    Cannot invoke "String.toUpperCase()" because "user.name" is null
    at Main.main(Main.java:5)

Example code:

User user = getUser();
String upperName = user.name.toUpperCase(); // NPE here

Message shows: "user.name" is null (not just “user”)

How to enable: -XX:+ShowCodeDetailsInExceptionMessages

Foreign-Memory Access API (JEP 370) - Incubator

Safe and efficient access to off-heap memory (outside Java heap).

Use cases:

  • Memory-mapped files
  • Inter-process communication
  • Native library integration

Example:

import jdk.incubator.foreign.*;

try (MemorySegment segment = MemorySegment.allocateNative(100)) {
    MemoryAddress base = segment.baseAddress();
    MemoryAccess.setIntAtOffset(segment, 0, 42);
    int value = MemoryAccess.getIntAtOffset(segment, 0);
    System.out.println(value); // 42
}

Benefits over sun.misc.Unsafe:

  • Safe (bounded memory access)
  • Automatic resource management
  • No security warnings

Packaging Tool (JEP 343) - Incubator

Create platform-specific installers for Java applications.

Supported formats:

  • Windows: msi, exe
  • macOS: pkg, dmg
  • Linux: deb, rpm

Command:

jpackage --input target/ \
         --name MyApp \
         --main-jar myapp.jar \
         --main-class com.example.Main \
         --type exe

Output: Native installer that bundles JRE with application

Benefits: End users don’t need separate Java installation

JFR Event Streaming (JEP 349)

Continuous monitoring with JDK Flight Recorder (JFR).

Before: JFR data accessible only in dumps (batch processing)

After: Stream JFR events in real-time for monitoring

Example:

import jdk.jfr.consumer.RecordingStream;

try (RecordingStream rs = new RecordingStream()) {
    rs.onEvent("jdk.CPULoad", event -> {
        System.out.println("CPU Load: " + event.getFloat("machineTotal"));
    });
    rs.start();
}

Use cases: Real-time dashboards, alerting systems, APM tools

Garbage Collection Improvements

NUMA-Aware Memory Allocation for G1 (JEP 345)

Improves G1 GC performance on NUMA (Non-Uniform Memory Access) systems.

What is NUMA: Multi-socket servers where memory access cost varies by CPU socket

Improvement: G1 now allocates memory local to the requesting thread’s CPU

Performance gain: Up to 30% throughput improvement on large NUMA systems

How to enable: -XX:+UseNUMA (with G1GC)

ZGC on macOS (JEP 364) and Windows (JEP 365)

Z Garbage Collector (ZGC) expanded to macOS and Windows.

Previously: Linux only

Now: Available on all major platforms

ZGC characteristics:

  • Pause times <10ms (even with TB-sized heaps)
  • Concurrent (doesn’t stop application threads)
  • Scalable (handles 8MB to 16TB heaps)

How to enable:

java -XX:+UseZGC -Xmx16g MyApp

Use cases: Low-latency applications, large heap requirements

Removals and Deprecations

CMS Garbage Collector Removed (JEP 363)

Concurrent Mark Sweep (CMS) GC removed (deprecated in Java 9).

Alternatives:

  • G1 GC (default since Java 9)
  • ZGC (for ultra-low latency)
  • Shenandoah (for low latency)

Migration: Remove -XX:+UseConcMarkSweepGC flag

Pack200 Tools and API Removed (JEP 367)

pack200/unpack200 compression tools removed (deprecated in Java 11).

Reason: Low adoption, maintenance burden, superseded by jlink

Alternative: Use jar with compression or jlink for custom runtimes

Other Notable Changes

JEP 343: Non-Volatile Mapped Byte Buffers - Support for NVM (non-volatile memory)

JEP 352: macOS Rendering Pipeline - Migrated from deprecated OpenGL to Apple Metal

JEP 362: Deprecate Solaris and SPARC Ports - Rarely used platforms marked for removal

Migration Considerations

Upgrading from Java 11 LTS:

  1. CMS GC removed: Migrate to G1 GC (usually drop-in replacement)
  2. Pack200 removed: Update build scripts if used
  3. Preview features: Enable with --enable-preview flag for Records, Text Blocks
  4. Deprecations: Review code for usage of deprecated APIs

Compatibility: Binary compatible with Java 11 (no breaking changes in standard APIs)

Related Topics

References

Sources:

Official OpenJDK JEPs:

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