Problems comparing dates with Calendar

Question

I am developing a system for hotel and reservation I need the date of entry is greater than or equal to that of the reservation, and the exit is greater than that of the entrance.
I made these conditions, but when I test the reservation date and entry date equal I can not make the registration.
I don’t know what could be wrong with my method code. Could someone help me??

private boolean verificaData(Calendar dcDataReserva, JDateChooser dcDataEntrada, JDateChooser dcDataSaida){

      Calendar Data_Reserva = Calendar.getInstance();
      Calendar Data_Entrada = dcDataEntrada.getCalendar();
      Calendar Data_Saida = dcDataSaida.getCalendar();
      boolean data;

      if(Data_Entrada.before(Data_Reserva) && (Data_Saida.before(Data_Entrada))){
          data= false;
      }else
          if((Data_Entrada.after(Data_Reserva)) && (Data_Saida.after(Data_Entrada))){
          data = true; 
          }else

              if(Data_Reserva.equals(Data_Entrada)){
                data = true;
              }else{
                data = false;
             }

              return data;    
    }

Answer 1

I think this is what you’re looking for:

private boolean verificaData(Calendar dataReserva, Calendar dataEntrada, Calendar dataSaida){
    return (dataEntrada.equals(dataReserva) || dataEntrada.after(dataReserva)) && dataEntrada.before(dataSaida);
}

If the date of entry is equal to or after the date of reservation, it is checks whether this is prior to the date of departure. If the first condition is false, there is no need to check if the exit date is correct.

I saw that the question was tagged with Java8. If you are really using version 8 of Java, you can replace Calendar for LocalDateTime, similar to Joda Time.

Answer 2

One of the ways to make this comparison is by using the method compareTo, evaluating their return:

return (dataEntrada.compareTo(dataReserva) >= 0 && dataSaida.compareTo(dataEntrada) > 0)

The return of compareTo can be:

• equal to 0 if both dates are equal;
• returns 1(greater than 0) if the leftmost date is later than the date passed as argument;
• returns -1 if the date on the left is earlier than the date passed as argument.

Example:

public static String validarDataDate(Calendar dataReserva, Calendar dataEntrada, Calendar dataSaida) {

    if(dataEntrada.compareTo(dataReserva) >= 0 && dataSaida.compareTo(dataEntrada) > 0){
        return "tudo certo";
    }else{
        return "algumas datas sao invalidas";
    }
}

public static void main (String[] args) throws java.lang.Exception
{
    Date dataReserva = new SimpleDateFormat("dd/MM/yyyy").parse("20/04/2016");
    Date dataEntrada = new SimpleDateFormat("dd/MM/yyyy").parse("22/04/2016");
    Date dataSaida = new SimpleDateFormat("dd/MM/yyyy").parse("27/04/2016");;
    Calendar cal1 =  Calendar.getInstance();
    Calendar cal2 =  Calendar.getInstance();
    Calendar cal3 =  Calendar.getInstance();
    cal1.setTime(dataReserva);
    cal2.setTime(dataEntrada);
    cal3.setTime(dataSaida);
    System.out.println(validarDataDate(cal1, cal2, cal3));// reserva menor que entrada que é menor que saida
    System.out.println(validarDataDate(cal2, cal2, cal3));// reserva igual a entrada que é menor que saida
    System.out.println(validarDataDate(cal2, cal1, cal3));// reserva maior que entrada que é menor que saida
    System.out.println(validarDataDate(cal1, cal3, cal2));// reserva menor que entrada que é maior que saida


}

Returning:

all right
all right
some dates are invalid
some dates are invalid

Functioning in the IDEONE.

The first comparison, the three dates perfectly meet your question condition, in the second comparison, the date of entry is after the reservation date and in the third comparison, the date of departure is before the date of entry.

In this answer there is also another way to compare dates using the new java-8.