如何使用符合特定条件的数组填充jcombobox

Question

当我尝试使用下面的代码时，列表中没有填充特定的数组，请帮助我在netbeans中编写GUI代码

private void bookingListJCBActionPerformed(java.awt.event.ActionEvent evt) {                                               

    for(int i = 0;i<dataSource.getBookingList().size();i++){
        Bookings tempBooking = dataSource.getBookingList().get(i);

        boolean tempFinish = tempBooking.getFinish();
        String tempMechanic = tempBooking.getMechanic();
        String tempClerk = tempBooking.getClerk();
        String tempService  = tempBooking.getService();

       if(tempFinish == true){
         bookingListJCB.addItem(tempBooking);
         mechanicJTF.setText(tempMechanic);
         seriveceClerkJTF.setText(tempMechanic);
         serviceJTF.setText(""+tempService );
         finishJTF.setText(""+tempFinish);
        }
    }


    // TODO add your handling code here:
} 

以下是预订课程，我不知道为什么组合框没有显示任何内容

public class Bookings {
private String vehicle;
private String clerk;
private String service;
private String mechanic;
private boolean finish;

public Bookings() {
}

public Bookings(String vehicle, String clerk, String service, String mechanic, boolean finish) {
    this.vehicle = vehicle;
    this.clerk = clerk;
    this.service = service;
    this.mechanic = mechanic;
    this.finish = finish;
}

public String getVehicle() {
    return vehicle;
}

public void setVehicle(String vehicle) {
    this.vehicle = vehicle;
}

public String getClerk() {
    return clerk;
}

public void setClerk(String clerk) {
    this.clerk = clerk;
}

public String getService() {
    return service;
}

public void setService(String service) {
    this.service = service;
}

public String getMechanic() {
    return mechanic;
}

public void setMechanic(String mechanic) {
    this.mechanic = mechanic;
}

public boolean getFinish() {
    return finish;
}

public void setFinish(boolean finish) {
    this.finish = finish;
}

@Override
public String toString() {
    return "Bookings{" + "vehicle=" + vehicle + ", clerk=" + clerk + ", service=" + service + ", mechanic=" + mechanic + ", finish=" + finish + '}';
} 

}