I'm stuck in this error that shows up " Operator ' ' cannot be applied to 'java.lang.String', 'void' " after I tried to fetch data from a list of an object with the help of foreach I don't understand what's the problem, this is where the problem show up

public void sendMailOwner(VacacionRequest PaidRequest) {
        CollaboratorDTO validator = OrganizationalUintService.findValidator(collaboratorTransformer.entityTranferToDTO(PaidRequest.getCollaborator()));
        EmailService.sendSimpleMessage(PaidRequest.getCollaborator().getEmail(),
                "EverHoliday",
                " Bonjour " PaidRequest.getCollaborator().getFirstname() " " PaidRequest.getCollaborator().getLastname() ","
                  "\n Votre demande de Congé payé du date " PaidRequest.getDatesRequest().forEach((p)->p.getStartDate) "au" PaidRequest.getDatesRequest().forEach((p)->p.getEndDate) " est en attente de validation par : "
                         validator.getLastname() " " validator.getFirstname()
                  " \n Cordialement.");
    }

PaidRequest.getDatesRequest().forEach((p)->p.getStartDate) as you can see i want to fetch all startdate from datesrequest list

this is DatesRequest Model

package com.example.demo.model;

import java.time.LocalDate;

import org.springframework.data.neo4j.core.schema.GeneratedValue;
import org.springframework.data.neo4j.core.schema.Id;
import org.springframework.data.neo4j.core.schema.Node;
@Node
public class DatesRequest {
    @Id @GeneratedValue
    private Long id;    
 private LocalDate startDate;
 private LocalDate endDate;
 private double duration;
public DatesRequest(LocalDate startDate, LocalDate endDate, double duration) {
    this.startDate = startDate;
    this.endDate = endDate;
    this.duration = duration;
}
public DatesRequest() {
}
public LocalDate getStartDate() {
    return startDate;
}
public void setStartDate(LocalDate startDate) {
    this.startDate = startDate;
}
public LocalDate getEndDate() {
    return endDate;
}
public void setEndDate(LocalDate endDate) {
    this.endDate = endDate;
}
public double getDuration() {
    return duration;
}
public void setDuration(double duration) {
    this.duration = duration;
}
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}

}

and this is where we declared DatesRequest in PaidRequest Model

public PaidRequest(LocalDate requestDate, String statut, String typeOfTime, List<DatesRequest> datesRequest,
        Collaborator collaborator, String description, double balanceUsed,String justification) {
    super(requestDate, statut, typeOfTime, datesRequest, collaborator);
    this.description = description;
    this.balanceUsed = balanceUsed;
    this.justification = justification;
}

CodePudding user response：

As long you concatenate strings the both arguments of ' ' operator must be strings. But PaidRequest.getDatesRequest().forEach((p)->p.getStartDate) this is not a string but void, if you want to get it as comma separeted string use something like:

String.join(",", PaidRequest.getDatesRequest().map((p)->p.getStartDate)) (remember to collect to list)

CodePudding user response：

This is happening because you are trying to join String with void datatype.

PaidRequest.getDatesRequest().forEach is returning void datatype.

If you want to join getStartDate to your string, then I would recommend extract it to Array or list & then join it later.