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Java / MapStruct Java Interview questions part 2

How do you map an enum to a different enum with mismatched constants?

By default MapStruct maps enum constants that share the exact same name automatically. When names differ between the source and target enums, @ValueMapping lets you specify the correspondence explicitly.

@Mapper
public interface StatusMapper {
    @ValueMapping(source = "ACTIVE", target = "ENABLED")
    @ValueMapping(source = "INACTIVE", target = "DISABLED")
    TargetStatus toTargetStatus(SourceStatus source);
}

You can also handle values with no equivalent using special targets like NULL (map to null) or ANY_UNMAPPED combined with a designated fallback constant, and MapStruct will warn at compile time if a source constant has no mapping rule and no equally-named match, so an unhandled enum value doesn't silently fail at runtime.

Enum constants with mismatched names are mapped explicitly using:
If a source enum constant has no matching rule or same-named target, MapStruct:

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