Getting null value for days calculated / added current date plus the user entered value

Question

Getting null value for days calculated / added current date plus the user entered value

We are calculating a column value based on the user entered value ie Number of days entered by the User plus the current date.

private Date setdaysAttendanceApprovedWithAdditionalDays(int daysAttendanceApproved2) {

    Date currentDate = new Date();
    Calendar c = Calendar.getInstance();
    c.setTime(currentDate);

    c.add(Calendar.DATE, daysAttendanceApproved2);

    Date currentDatePlusUserInput = c.getTime();
    return currentDatePlusUserInput;
}

Desired Output

If a user enters the value of 10 then 8 May 2020 Plus 10 the Output would be 18-May-2020 in the set NewDate

Issue

the setNewdate setdaysAttendanceApprovedWithAdditionalDays is the being set to null

<h:form>
<p:panel id="panel" header="New User">

    <h:panelGrid columns="3" cellpadding="5">
        <p:outputLabel for="Additional Days" value="Additionaldays:" />
        <p:inputText id="additionaldays" value="#{saveMB.attendanceApprovalEntity.daysAttendanceApproved}">
        </p:inputText>
    </h:panelGrid>

    <p:commandButton value="Save" actionListener="#{saveMB.approveAttendance}" />
</p:panel>
</h:form>

saveMB.java

@ManagedBean(name = "saveMB")
@ViewScoped
public class saveMB implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger logger = LoggerFactory.getLogger(saveMB.class);

private Integer daysAttendanceApproved;

public Integer getdaysAttendanceApproved() {
    return daysAttendanceApproved;
}

public void setdaysAttendanceApproved(Integer daysAttendanceApproved) {
    this.daysAttendanceApproved = daysAttendanceApproved;
}

private Date newdate;

public Date getNewdate() {
    return newdate;
}

public void setNewdate(Date newdate) {
    this.newdate = newdate;
}

private AttendanceFlow attendanceApprovalEntity;

public AttendanceFlow getattendanceApprovalEntity() {
    return attendanceApprovalEntity;
}

public void setattendanceApprovalEntity(AttendanceFlow attendanceApprovalEntity) {
    this.attendanceApprovalEntity = attendanceApprovalEntity;
}


@PostConstruct
public void init() {

    ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
    Map<String, String> params = externalContext.getRequestParameterMap();

}

private Date setdaysAttendanceApprovedWithAdditionalDays(int daysAttendanceApproved2) {

    Date currentDate = new Date();
    Calendar c = Calendar.getInstance();
    c.setTime(currentDate);

    c.add(Calendar.DATE, daysAttendanceApproved2);

    Date currentDatePlusUserInput = c.getTime();
    return currentDatePlusUserInput;
}

public void approveAttendance(AjaxBehaviorEvent event) {
    FacesContext facesContext = FacesContext.getCurrentInstance();
    try {

        this.attendanceApprovalEntity.setNewdate(setdaysAttendanceApprovedWithAdditionalDays(this.attendanceApprovalEntity.getdaysAttendanceApproved())); 

    } catch (Exception e) {}

}
}

AttendanceFlow.java

@Entity
@Table(name = "ATTENDANCE_FLOW")
@NamedQuery(name = "AttendanceFlow.findAll", query = "SELECT h FROM AttendanceFlow h")
public class AttendanceFlow implements Serializable {

private static final long serialVersionUID = 1L;

@Id
@SequenceGenerator(name = "ATTENDANCE_FLOW_ID_GENERATOR", sequenceName = "ATTENDANCE_FLOW_ID_SEQ", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ATTENDANCE_FLOW_ID_GENERATOR")
@Column(name = "ATTENDANCE_FLOW_ID")
private Integer AttendanceFlowId;

@Column(name = "DAYS_ATTENDANCE_APPROVED")
private Integer daysAttendanceApproved;

@Column(name = "NEW_DATE")
@Temporal(TemporalType.DATE)
private Date newdate;

public Date getNewdate() {
    return newdate;
}

public void setNewdate(Date newdate) {
    this.newdate = newdate;
}    

public Integer getAttendanceFlowId() {
    return AttendanceFlowId;
}

public void setAttendanceFlowId(Integer AttendanceFlowId) {
    this.AttendanceFlowId = AttendanceFlowId;
}

public Integer getdaysAttendanceApproved() {
    return daysAttendanceApproved;
}

public void setdaysAttendanceApproved(Integer daysAttendanceApproved) {
    this.daysAttendanceApproved = daysAttendanceApproved;
}

}

While Debugging I can find the value of

 this.attendanceApprovalEntity.getdaysAttendanceApproved   

ie user entered value something like 10 , but I could not proceed afterthat

Answer 1

LocalDate::plusDays

Use LocalDate instead of outdated Date and Calendar. Check this for more details.

Do it as follows:

private LocalDate setDaysAttendanceApprovedWithAdditionalDays(int daysAttendanceApproved) {
    LocalDate date = LocalDate.now();
    return date.plusDays(daysAttendanceApproved);
}

A quick demo:

import java.time.LocalDate;

public class Main {
    public static void main(String[] args) {
        // Test
        System.out.println(setDaysAttendanceApprovedWithAdditionalDays(10));
    }

    static LocalDate setDaysAttendanceApprovedWithAdditionalDays(int daysAttendanceApproved) {
        LocalDate date = LocalDate.now();
        return date.plusDays(daysAttendanceApproved);
    }
}

Output:

2020-05-18

JPA and java.time

Remove @Temporal annotation from the attribute. Also, note that if you are using JPA 2.1 or earlier, you need to write a converter as shown here. If you are are using JPA 2.2 or later, you do not need any converter.

Answer 2

Use the GregorianCalendar class instead. Today's date can be obtained with date=new GregorianCalendar() and the number entered by the user can be added with date.add(Calendar.DAY_OF_MONTH,number).