How to collect list values in to collector object - collectors

Question

I am trying to collect 2 data fields from the list object.
I am using Employee object:
public class Employee
{
private long id;
private Source source;
private String name;
private String gender;
// getters
private Builder toBuilder(Builder builder)
{
builder.id = this.summaryDataId;
builder.name = this.name;
builder.gender = this.gender;
builder.source = this.source;
return builder;
}
getting employee data into a list in a service class
final List<Employee> employeeData = employeeDao.retrieveEmployeeData(emp.getID());
and then trying to create a list with employeeId and sourceid (Ex: 1234:3). for this I am trying to use collectors.toList
List<String> employeeCollector = employeeData.stream()
.filter(s -> s.getId != null)
.filter(s -> s.getSource() != null && s.getSource().getId() != null)
.collect(Collectors.toList());
how do i get employeeid:souceid format using collectors.toLis()

Answer 1

You just need an intermediate operation map to extract the employee id and source id
List<String> employeeCollector = employeeData.stream()
.filter(s -> s.getId != null)
.filter(s -> s.getSource() != null && s.getSource().getId() != null)
.map(s-> String.format("%s:%s",s.getId(),s.getSource().getId()))
.collect(Collectors.toList());