ModelMapper, mapping list of Entites to List of DTO objects

considering you have a list of Post Entity (postEntityList) and a PostDTO class, you can try following:

use the following imports to get the desired results

import org.modelmapper.ModelMapper;
import org.modelmapper.TypeToken;
import java.lang.reflect.Type;

use the below code

Type listType = new TypeToken<List<PostDTO>>(){}.getType();
List<PostDTO> postDtoList = modelmapper.map(postEntityList,listType);

since you want to convert Entity to Dto, you can try the following one

List<PostDTO> entityToDto = modelMapper.map(postEntity, new TypeToken<List<PostDTO>>(){}.getType());

Try the following simple way:

List<PostDTO> postDtoList = Arrays.asList(modelMapper.map(postEntityList, PostDTO[].class));

You can create util class:

public class ObjectMapperUtils {

    private static final ModelMapper modelMapper;

    /**
     * Model mapper property setting are specified in the following block.
     * Default property matching strategy is set to Strict see {@link MatchingStrategies}
     * Custom mappings are added using {@link ModelMapper#addMappings(PropertyMap)}
     */
    static {
        modelMapper = new ModelMapper();
        modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
    }

    /**
     * Hide from public usage.
     */
    private ObjectMapperUtils() {
    }

    /**
     * <p>Note: outClass object must have default constructor with no arguments</p>
     *
     * @param <D>      type of result object.
     * @param <T>      type of source object to map from.
     * @param entity   entity that needs to be mapped.
     * @param outClass class of result object.
     * @return new object of <code>outClass</code> type.
     */
    public static <D, T> D map(final T entity, Class<D> outClass) {
        return modelMapper.map(entity, outClass);
    }

    /**
     * <p>Note: outClass object must have default constructor with no arguments</p>
     *
     * @param entityList list of entities that needs to be mapped
     * @param outCLass   class of result list element
     * @param <D>        type of objects in result list
     * @param <T>        type of entity in <code>entityList</code>
     * @return list of mapped object with <code><D></code> type.
     */
    public static <D, T> List<D> mapAll(final Collection<T> entityList, Class<D> outCLass) {
        return entityList.stream()
                .map(entity -> map(entity, outCLass))
                .collect(Collectors.toList());
    }

    /**
     * Maps {@code source} to {@code destination}.
     *
     * @param source      object to map from
     * @param destination object to map to
     */
    public static <S, D> D map(final S source, D destination) {
        modelMapper.map(source, destination);
        return destination;
    }
}

And use it for your needs:

List<PostDTO> listOfPostDTO = ObjectMapperUtils.mapAll(listOfPosts, PostDTO.class);