[BAEL-4093] Mapping Collections with MapStruct (#9597)

Co-authored-by: Bogdan Feraru <bogdan.feraru@iquestgroup.com>

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/dto/CompanyDTO.java

@@ -0,0 +1,25 @@
+package com.baeldung.mapstruct.mappingCollections.dto;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CompanyDTO {
+
+    private List<EmployeeDTO> employees;
+
+    public List<EmployeeDTO> getEmployees() {
+        return employees;
+    }
+
+    public void setEmployees(List<EmployeeDTO> employees) {
+        this.employees = employees;
+    }
+
+    public void addEmployee(EmployeeDTO employeeDTO) {
+        if (employees == null) {
+            employees = new ArrayList<>();
+        }
+
+        employees.add(employeeDTO);
+    }
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/dto/EmployeeDTO.java

@@ -0,0 +1,23 @@
+package com.baeldung.mapstruct.mappingCollections.dto;
+
+public class EmployeeDTO {
+
+    private String firstName;
+    private String lastName;
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/dto/EmployeeFullNameDTO.java

@@ -0,0 +1,14 @@
+package com.baeldung.mapstruct.mappingCollections.dto;
+
+public class EmployeeFullNameDTO {
+
+    private String fullName;
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/mapper/CompanyMapper.java

@@ -0,0 +1,11 @@
+package com.baeldung.mapstruct.mappingCollections.mapper;
+
+import com.baeldung.mapstruct.mappingCollections.dto.CompanyDTO;
+import com.baeldung.mapstruct.mappingCollections.model.Company;
+import org.mapstruct.Mapper;
+
+@Mapper(uses = EmployeeMapper.class)
+public interface CompanyMapper {
+
+    CompanyDTO map(Company company);
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/mapper/CompanyMapperAdderPreferred.java

@@ -0,0 +1,12 @@
+package com.baeldung.mapstruct.mappingCollections.mapper;
+
+import com.baeldung.mapstruct.mappingCollections.dto.CompanyDTO;
+import com.baeldung.mapstruct.mappingCollections.model.Company;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED)
+public interface CompanyMapperAdderPreferred {
+
+    CompanyDTO map(Company company);
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/mapper/EmployeeFullNameMapper.java

@@ -0,0 +1,20 @@
+package com.baeldung.mapstruct.mappingCollections.mapper;
+
+import com.baeldung.mapstruct.mappingCollections.dto.EmployeeFullNameDTO;
+import com.baeldung.mapstruct.mappingCollections.model.Employee;
+import org.mapstruct.Mapper;
+
+import java.util.List;
+
+@Mapper
+public interface EmployeeFullNameMapper {
+
+    List<EmployeeFullNameDTO> map(List<Employee> employees);
+
+    default EmployeeFullNameDTO map(Employee employee) {
+        EmployeeFullNameDTO employeeInfoDTO = new EmployeeFullNameDTO();
+        employeeInfoDTO.setFullName(employee.getFirstName() + " " + employee.getLastName());
+
+        return employeeInfoDTO;
+    }
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/mapper/EmployeeMapper.java

@@ -0,0 +1,19 @@
+package com.baeldung.mapstruct.mappingCollections.mapper;
+
+import com.baeldung.mapstruct.mappingCollections.dto.EmployeeDTO;
+import com.baeldung.mapstruct.mappingCollections.model.Employee;
+import org.mapstruct.Mapper;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+@Mapper
+public interface EmployeeMapper {
+
+    List<EmployeeDTO> map(List<Employee> employees);
+
+    Set<EmployeeDTO> map(Set<Employee> employees);
+
+    Map<String, EmployeeDTO> map(Map<String, Employee> idEmployeeMap);
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/model/Company.java

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+package com.baeldung.mapstruct.mappingCollections.model;
+
+import java.util.List;
+
+public class Company {
+
+    private List<Employee> employees;
+
+    public List<Employee> getEmployees() {
+        return employees;
+    }
+
+    public void setEmployees(List<Employee> employees) {
+        this.employees = employees;
+    }
+}

mapstruct/src/main/java/com/baeldung/mapstruct/mappingCollections/model/Employee.java

@@ -0,0 +1,28 @@
+package com.baeldung.mapstruct.mappingCollections.model;
+
+public class Employee {
+
+    private String firstName;
+    private String lastName;
+
+    public Employee(String firstName, String lastName) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+}