Why Do Companies Still Stick to JDK 8 When JDK 25 Is Available?

Why many enterprises still run on JDK 8

Even after newer LTS releases (JDK 11, 17, 21, 25) are available, a large number of production systems remain on JDK 8. The main reasons are technical compatibility, proven stability, migration cost, and long‑term support guarantees.

1. Compatibility challenges

1.1 API removals

JDK 9+ removes internal APIs that were commonly used in JDK 8 code. For example, sun.misc.BASE64Encoder no longer exists. The portable replacement is java.util.Base64:

import java.util.Base64;

public class NewBase64Example {
    public String encode(String data) {
        Base64.Encoder encoder = Base64.getEncoder();
        return encoder.encodeToString(data.getBytes());
    }
    public static void main(String[] args) {
        NewBase64Example ex = new NewBase64Example();
        System.out.println(ex.encode("Hello, World!"));
    }
}

Large code bases may contain hundreds of such calls, so a migration requires systematic refactoring.

1.2 Java Platform Module System (JPMS)

Since JDK 9 the module system enforces explicit dependencies. Accessing internal classes like sun.misc.Unsafe now requires a requires jdk.unsupported; clause in module-info.java:

module com.example.myapp {
    requires java.base;
    requires jdk.unsupported; // explicit declaration
    exports com.example.mypackage;
}

Missing module declarations cause ClassNotFoundException at runtime.

2. Stability and maturity

2.1 Proven runtime

JDK 8’s HotSpot VM has been battle‑tested for a decade. Its memory management, garbage collection (Parallel GC), and JMX monitoring are well understood. Newer collectors such as ZGC (JDK 15+) and Shenandoah (JDK 12+) offer lower pause times but introduce higher memory overhead and may exhibit edge‑case behavior in legacy workloads.

2.2 Ecosystem integration

All major frameworks (Spring Boot 2.x, MyBatis 3.5, Hibernate 5.6) provide first‑class support for JDK 8. Upgrading often requires updating module descriptors or dependency versions, which can be non‑trivial for monolithic applications.

3. Learning curve and team productivity

3.1 New language features

JDK 9 – module system

JDK 10 – var type inference

JDK 11 – HTTP Client API

JDK 14 – records, pattern matching

JDK 17 – sealed classes

JDK 21 – virtual threads

Adopting these features requires training and code‑style adjustments. Example of a POJO replaced by a record:

// JDK 8 style
public class User {
    private final String name;
    private final int age;
    private final String email;
    public User(String name, int age, String email) {
        this.name = name;
        this.age = age;
        this.email = email;
    }
    // getters, equals, hashCode, toString …
}

// JDK 14+ record
public record User(String name, int age, String email) {}

3.2 Skill inertia

Teams that have mastered JDK 8 can deliver features quickly. Introducing unfamiliar syntax or APIs can temporarily reduce velocity and increase maintenance overhead due to inconsistent code style.

4. Third‑party library compatibility

4.1 Framework version matrix

Typical support matrix:

Spring Boot 2.7 – supports JDK 8, 11, 17 (not JDK 21)

Spring Boot 3.0 – requires at least JDK 11

MyBatis 3.5, Hibernate 5.6 – support JDK 8 through JDK 21

When a library depends on a specific transitive version (e.g., Guava 20.0 vs 30.0), upgrading the JDK may force a dependency upgrade, leading to version conflicts that must be resolved manually.

5. Performance and resource considerations

5.1 Garbage‑collector evolution

Summary of GC characteristics:

Parallel GC (JDK 8+) – long pauses, high throughput, low memory overhead.

G1 GC (JDK 9+) – moderate pauses and throughput.

ZGC (JDK 15+) – sub‑millisecond pauses, higher memory usage.

Shenandoah (JDK 12+) – short pauses, moderate throughput, high memory usage.

5.2 Virtual threads (JDK 21)

Virtual threads simplify IO‑bound concurrency. A classic thread‑pool implementation:

public class TraditionalThreadExample {
    private final ExecutorService executor = Executors.newFixedThreadPool(100);
    public void processRequests(List<Request> requests) {
        List<CompletableFuture<Result>> futures = requests.stream()
            .map(r -> CompletableFuture.supplyAsync(() -> process(r), executor)
            .collect(Collectors.toList());
        CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])).join();
    }
    private Result process(Request r) { /* … */ }
}

Using virtual threads:

public class VirtualThreadExample {
    public void processRequests(List<Request> requests) throws Exception {
        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
            List<CompletableFuture<Result>> futures = requests.stream()
                .map(r -> CompletableFuture.supplyAsync(() -> process(r), executor)
                .collect(Collectors.toList());
            CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])).join();
        }
    }
    private Result process(Request r) { /* … */ }
}

Virtual threads are ideal for high‑concurrency, IO‑heavy services; CPU‑bound workloads may still prefer the classic model.

6. Commercial support and cost

6.1 LTS lifecycle

JDK 8 (LTS) receives public updates until 2030. JDK 11 is also LTS. Non‑LTS releases require upgrades every six months, increasing licensing and maintenance effort.

6.2 ROI model example

public class UpgradeROI {
    private double hardwareCost, softwareCost, manpowerCost, trainingCost, testingCost;
    private double riskCost, downtimeCost;
    private double performanceGain, maintenanceGain, securityGain, featureGain;
    public boolean shouldUpgrade() {
        double totalCost = hardwareCost + softwareCost + manpowerCost + trainingCost +
                          testingCost + riskCost + downtimeCost;
        double totalGain = performanceGain + maintenanceGain + securityGain + featureGain;
        return totalGain > totalCost * 1.5; // require >150% ROI
    }
}

Enterprises weigh direct costs (hardware, licenses, manpower) against benefits (performance, security, new features).

7. Toolchain and diagnostics

7.1 IDE and build‑tool support

IntelliJ IDEA, Eclipse, Maven, and Gradle all support JDK 8 through JDK 21, but migration may expose configuration quirks (e.g., source/target compatibility, module path settings).

7.2 Monitoring

JDK 8 relies on JMX for custom metrics:

public class JmxExample {
    private final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
    public void register() throws Exception {
        ObjectName name = new ObjectName("com.example:type=Metric");
        mbs.registerMBean(new Metric(), name);
    }
}

JDK 14+ introduces Java Flight Recorder (JFR) for low‑overhead event recording:

public class JfrExample {
    @Label("Custom Event")
    @Description("Business event")
    static class CustomEvent extends Event {
        @Label("Data") private String data;
    }
    public void record(String d) {
        CustomEvent e = new CustomEvent();
        e.data = d;
        e.commit();
    }
}

Conclusion

Enterprises stay on JDK 8 because it offers:

Stable, well‑tested runtime and GC behavior.

Broad ecosystem compatibility with minimal migration risk.

Long‑term support that aligns with corporate upgrade cycles.

Known team skill set and tooling.

For new projects or when specific benefits (e.g., virtual threads, low‑pause GC, newer language features) are required, adopting a newer LTS release such as JDK 17 or JDK 21 is advisable. Migration should be incremental—upgrade modules or services one at a time, run comprehensive integration tests, and verify third‑party library compatibility before committing to a full platform switch.