Understanding Java Enum values() Method and Its Impact on Garbage Collection
The article explains that Java's enum values() method creates a new array on each call by cloning an internal $VALUES field, which contradicts object‑reuse principles and adds GC pressure, and it suggests caching the returned array when frequent calls are needed.
In many projects developers repeatedly invoke the values() method of an enum, not realizing that each call generates a fresh enum array, which goes against the principle of reusing immutable objects and can increase garbage‑collection overhead.
The compiler automatically creates a synthetic field $VALUES of type EnumDemo[] and initializes it in a static block. It also generates a static values() method whose return type is EnumDemo[]. According to the bytecode, the implementation of values() simply returns $VALUES.clone(), i.e., it clones the internal array and returns a new one each time.
Because each invocation allocates a new array, frequent calls to values() can put unnecessary load on the garbage collector. To mitigate this, the article recommends caching the array returned by values() and reusing it whenever the enum values need to be accessed many times.
Summary : The enum values() method always creates a new array by cloning the internal $VALUES field; to reduce GC pressure, cache the result if the method is called often.
Signed-in readers can open the original source through BestHub's protected redirect.
This article has been distilled and summarized from source material, then republished for learning and reference. If you believe it infringes your rights, please contactand we will review it promptly.
Cognitive Technology Team
Cognitive Technology Team regularly delivers the latest IT news, original content, programming tutorials and experience sharing, with daily perks awaiting you.
How this landed with the community
Was this worth your time?
0 Comments
Thoughtful readers leave field notes, pushback, and hard-won operational detail here.