EnumTypeAdapter constructor optimization #2734
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| } | ||
| } | ||
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| Field[] constantFields = constantFieldsList.toArray(new Field[0]); | ||
| AccessibleObject.setAccessible(constantFields, true); | ||
| // Trim the array to the new length |
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My initial thought was that most of the time you won't need to do this. Every call to getDeclaredFields() returns a new array and if there are no fields that are not enum constants then you can just use that array as is. However, with javac at least, it turns out that there is always a private $VALUES field which is an array that is cloned every time values() is called on the enum. So perhaps add a further note like "This will always be needed because of the $VALUES field."
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Good call; comment added.
Also, the enum constants all seem to appear first among the declared fields, which would allow reusing the unmodified array (up to the first non-enum constant), but the documentation warns not to rely on that behavior. But at least branch prediction should be good.
Purpose
Improve the runtime performance of
EnumTypeAdapter(Class).Description
Eliminate the temporary
ArrayListin favor of array truncation via<T> java.util.Arrays.copyOf(T[],int).