{"id":2065,"date":"2026-01-19T02:38:05","date_gmt":"2026-01-18T13:38:05","guid":{"rendered":"https:\/\/www.ronella.xyz\/?p=2065"},"modified":"2026-01-19T02:38:05","modified_gmt":"2026-01-18T13:38:05","slug":"mapstruct-imports-pure-java-code","status":"publish","type":"post","link":"https:\/\/www.ronella.xyz\/?p=2065","title":{"rendered":"MapStruct Imports: Pure Java Code"},"content":{"rendered":"

MapStruct's imports<\/code> attribute brings external types into scope for generated mappers. This guide focuses purely on the working code demonstrating imports in action.<\/p>\n

Domain Model<\/h2>\n

Abstract base entity:<\/strong><\/p>\n

package com.example.domain;\n\npublic abstract class AbstractBaseEntity {\n    private Long id;\n\n    public Long getId() { return id; }\n    public void setId(Long id) { this.id = id; }\n\n    public abstract String getStatus();\n}<\/code><\/pre>\n
Source entity:<\/strong><\/p>\n
package com.example.domain;\n\npublic class UserEntity extends AbstractBaseEntity {\n    private String username;\n    private String email;\n\n    public String getUsername() { return username; }\n    public void setUsername(String username) { this.username = username; }\n\n    public String getEmail() { return email; }\n    public void setEmail(String email) { this.email = email; }\n\n    @Override\n    public String getStatus() { return "ACTIVE"; }\n}<\/code><\/pre>\n
Target DTO:<\/strong><\/p>\n
package com.example.dto;\n\npublic class UserDto {\n    private Long id;\n    private String username;\n    private String email;\n    private String statusInfo;\n\n    \/\/ getters\/setters\n    public Long getId() { return id; }\n    public void setId(Long id) { this.id = id; }\n\n    public String getUsername() { return username; }\n    public void setUsername(String username) { this.username = username; }\n\n    public String getEmail() { return email; }\n    public void setEmail(String email) { this.email = email; }\n\n    public String getStatusInfo() { return statusInfo; }\n    public void setStatusInfo(String statusInfo) { this.statusInfo = statusInfo; }\n\n    @Override\n    public String toString() {\n        return "UserDto{id=" + id + ", username='" + username + "', statusInfo='" + statusInfo + "'}";\n    }\n}<\/code><\/pre>\n
Mapper with Imports<\/h2>\n
package com.example.mapper;\n\nimport com.example.dto.UserDto;\nimport com.example.domain.UserEntity;\nimport org.mapstruct.Mapper;\nimport org.mapstruct.Mapping;\nimport java.util.List;\n\n@Mapper(imports = com.example.domain.AbstractBaseEntity.class)\npublic interface UserMapper {\n\n    @Mapping(target = "id", source = "id")\n    @Mapping(target = "username", source = "username")\n    @Mapping(target = "email", source = "email")\n    @Mapping(target = "statusInfo", expression = "java( ((AbstractBaseEntity) entity).getStatus() + \\" (processed)\\")")\n    UserDto toDto(UserEntity entity);\n\n    List<UserDto> toDtos(List<UserEntity> entities);\n}<\/code><\/pre>\n
Usage Code<\/h2>\n
package com.example.demo;\n\nimport com.example.domain.UserEntity;\nimport com.example.dto.UserDto;\nimport com.example.mapper.UserMapper;\nimport org.mapstruct.factory.Mappers;\n\npublic class MapStructDemo {\n    private static final UserMapper MAPPER = Mappers.getMapper(UserMapper.class);\n\n    public static void main(String[] args) {\n        UserEntity entity = new UserEntity();\n        entity.setId(42L);\n        entity.setUsername("john_doe");\n        entity.setEmail("john@example.com");\n\n        UserDto dto = MAPPER.toDto(entity);\n        System.out.println("Mapped DTO: " + dto);\n    }\n}<\/code><\/pre>\n
Generated Code Insight<\/h2>\n
MapStruct generates UserMapperImpl<\/code> with automatic import:<\/p>\n
package com.example.mapper;\n\nimport com.example.domain.AbstractBaseEntity; \/\/ Added by imports attribute\nimport com.example.domain.UserEntity;\nimport com.example.dto.UserDto;\nimport java.util.ArrayList;\nimport java.util.List;\nimport javax.annotation.processing.Generated;\n\n@Generated(\n    value = "org.mapstruct.ap.MappingProcessor",\n    comments = "version: 1.6.3, compiler: IncrementalProcessingEnvironment from gradle-language-java-9.2.0.jar, environment: Java 25 (Oracle Corporation)"\n)\npublic class UserMapperImpl implements UserMapper {\n\n    @Override\n    public UserDto toDto(UserEntity entity) {\n        if ( entity == null ) {\n            return null;\n        }\n\n        UserDto userDto = new UserDto();\n\n        userDto.setId( entity.getId() );\n        userDto.setUsername( entity.getUsername() );\n        userDto.setEmail( entity.getEmail() );\n\n        userDto.setStatusInfo( ((AbstractBaseEntity) entity).getStatus() + " (processed)" );\n\n        return userDto;\n    }\n\n    @Override\n    public List<UserDto> toDtos(List<UserEntity> entities) {\n        if ( entities == null ) {\n            return null;\n        }\n\n        List<UserDto> list = new ArrayList<UserDto>( entities.size() );\n        for ( UserEntity userEntity : entities ) {\n            list.add( toDto( userEntity ) );\n        }\n\n        return list;\n    }\n}\n<\/code><\/pre>\n
Why Imports Are Required<\/h2>\n
\u274c Without imports<\/code> attribute:<\/strong><\/p>\n
\/\/ GENERATED CODE FAILS TO COMPILE:\n\/\/ error: cannot find symbol\n\/\/ symbol: class AbstractBaseEntity\n\/\/ ((AbstractBaseEntity) entity).getStatus()<\/code><\/pre>\n
\u2705 With imports = AbstractBaseEntity.class<\/code>:<\/strong><\/p>\n
\/\/ GENERATED CODE WORKS PERFECTLY:\n\/\/ import com.example.domain.AbstractBaseEntity;\n\/\/ ((AbstractBaseEntity) entity).getStatus() \u2713<\/code><\/pre>\n
Multiple Imports Pattern<\/h2>\n
@Mapper(imports = { \n    com.example.domain.AbstractBaseEntity.class,\n    java.time.LocalDateTime.class \n})\npublic interface AdvancedUserMapper {\n\n    @Mapping(target = "createdAt", expression = "java(LocalDateTime.now())")\n    @Mapping(target = "fullInfo", expression = "java(entity.getUsername() + \\" <\\" + ((AbstractBaseEntity)entity).getStatus() + \\">\\")")\n    UserDto toDto(UserEntity entity);\n}<\/code><\/pre>\n
The imports<\/code> attribute eliminates compilation errors when mappings reference types across packages or inheritance hierarchies.<\/p>\n","protected":false},"excerpt":{"rendered":"
MapStruct’s imports attribute brings external types into scope for generated mappers. This guide focuses purely on the working code demonstrating imports in action. Domain Model Abstract base entity: package com.example.domain; public abstract class AbstractBaseEntity { private Long id; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[91],"tags":[],"_links":{"self":[{"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/posts\/2065"}],"collection":[{"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2065"}],"version-history":[{"count":1,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/posts\/2065\/revisions"}],"predecessor-version":[{"id":2066,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=\/wp\/v2\/posts\/2065\/revisions\/2066"}],"wp:attachment":[{"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2065"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2065"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ronella.xyz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2065"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}