Why Companies Still Cling to JDK 8 After JDK 25? A Deep Technical Analysis

Background

Even though newer JDK versions bring attractive features and performance gains, many developers notice that new projects still use JDK 8 while older systems stubbornly stay on it. The article investigates the technical and business reasons behind this phenomenon.

1. Compatibility Issues

1.1 API Changes

New JDK releases remove or replace internal APIs. For example, sun.misc.BASE64Encoder works in JDK 8 but is removed after JDK 9, requiring migration to java.util.Base64:

import sun.misc.BASE64Encoder;
public class OldBase64Example {
    public String encode(String data) {
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(data.getBytes());
    }
}

import java.util.Base64;
public class NewBase64Example {
    public String encode(String data) {
        Base64.Encoder encoder = Base64.getEncoder();
        return encoder.encodeToString(data.getBytes());
    }
}

1.2 JPMS (Module System)

JDK 9 introduced the module system, causing module declarations and requires statements. Projects that rely on internal APIs must explicitly declare dependencies such as requires jdk.unsupported;, otherwise compilation fails.

2. Stability and Maturity

JDK 8 has been battle‑tested for nearly a decade, offering a stable HotSpot VM and well‑known garbage collectors. Newer runtimes (e.g., GraalVM) show promising benchmarks but lack the same production‑grade track record.

3. Learning Curve and Team Adaptation

New language features (records, pattern matching, sealed classes, virtual threads) improve developer productivity but require training. Large codebases may need extensive refactoring, and mixed coding styles can increase maintenance overhead.

4. Third‑Party Dependency Compatibility

Frameworks and libraries often lag behind JDK releases. For instance, Spring Boot 2.7 fully supports JDK 8‑11, while Spring Boot 3.0 requires at least JDK 17. Upgrading may force dependency upgrades, leading to version conflicts.

5. Performance and Resource Considerations

5.1 Garbage Collector Evolution

JDK 8 uses Parallel GC, which has longer pause times but low overhead. Newer collectors like ZGC and Shenandoah provide sub‑millisecond pauses at the cost of higher memory usage. Choosing a GC depends on workload characteristics.

5.2 Virtual Threads (JDK 21)

Virtual threads simplify high‑concurrency code but require JDK 21+. Migration involves replacing traditional thread‑pool code with Executors.newVirtualThreadPerTaskExecutor(), which may affect existing monitoring and profiling tools.

6. Commercial Support and Cost

JDK 8 and JDK 11 are LTS releases with long‑term vendor support, while many intermediate versions have short support windows. Companies must weigh licensing, training, testing, and downtime costs against potential performance gains.

7. Toolchain and Infrastructure

Modern IDEs (IntelliJ IDEA, Eclipse) and build tools (Maven, Gradle) support recent JDKs, but older plugins or CI pipelines may need updates. Monitoring tools also evolve: JMX is common for JDK 8, while JFR becomes the default in newer releases.

Conclusion

Sticking with JDK 8 is often a rational decision driven by risk mitigation, cost control, and compatibility guarantees. However, new projects can benefit from LTS releases like JDK 17 or JDK 21, especially for IO‑bound workloads that leverage virtual threads. A pragmatic migration strategy involves incremental module‑by‑module upgrades, thorough testing, and a clear ROI analysis.