# Supported Java Features
{% hint style="warning" %}
**This is the manual for older MicroStream versions (Version < 5.0).**
**The new documentation (Version >= 5.0) is located at:**
[https://docs.microstream.one/](https://docs.microstream.one/manual)
{% endhint %}
| Feature | Supported | Note |
| ----------------------------------------------------------------------------------- | -------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Classes |  | |
| Classes without default constructor |  | |
| Abstract classes / Interfaces |  | Perfectly handleable as types, but there can never be instances to be persisted in the first place. |
| Inner classes |  | |
| Anonymous inner classes |  | |
| Primitives |  | |
| References |  | |
| Final fields |  | |
| Static fields |  | Not supported since they are outside of an entity graph / a database, i.e. potentially shared by multiple graphs. |
| Constant primitives |  | No sense in persisting those. These are just plain trivial values outside of an entity graph / a database. |
| Constant instances |  | Must be registered for loading to update them instead of creating independent new instances. |
| Primitive arrays |  | |
| Object arrays |  | |
| Multi dimensional arrays |  | Technically the same as object arrays as every array is an object itself. |
| JDK value types
(String, Number types, Date, File, Locale, Optional, ...)
|  | Optimized handling via custom TypeHandlers. |
| Collections |  | Via generic handling logic (List, Set, Map, etc.).
Optimal handling required tailored TypeHandler (e.g. correctly handling loadFactor in java.util.HashMap)
|
| Nested Collections |  | |
| JVM system-tied classes
(Thread, ClassLoader, WeakReference, ...)
|  | Technically handleable, but handling system-instances could cause fatal problems (e.g. start a Thread just from loading data), so it is intentionally disabled. |
| JVM external-tied classes
(IO-Streams, FileChannel, ...)
|  | Technically handleable, but external dependencies could cause fatal problems (e.g. existence of a referenced file), so it is intentionally disabled. |
## Java 5
| Feature | Supported | Note |
| -------------------------- | -------------------------------- | ----------------------------------------------------------------------------------------- |
| Enums |  | Automatically handled as constant instances to maintain referential integrity / identity. |
| Enums with mutable state |  | |
| Enums anonymous subclasses |  | |
## Java 8
| Feature | Supported | Note |
| ------- | -------------------------------- | ----------------------------------------------------------------------------------------------- |
| Lambdas |  | Type-handleable in theory. But JVM is not able to resolve its own type definitions for lambdas. |
## Java 14
| Feature | Supported | Note |
| ------- | -------------------------------- | ------------------------------------------ |
| Records |  | Records are mere syntax sugar for classes. |
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