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Before registering a person I need to validate that the date of birth is not greater than a previous date e.g. (01/01/1970) and the current date.

Method that does not work for me:

 public void agregarPersona() throws Exception {
            ImplPersonaD dao;
            try {
            Date date = new Date();
            DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
            String fechaActual = String.valueOf(dateFormat.format(date));      
            String fechaPasada = "01/01/1970";
                if(fechaPasada  > persona.getFechNac() <= fechaActual ){
                dao = new ImplPersonaD();
                dao.agregarPersona(persona);
                FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_INFO, "Satisfactorio", "Ingresado correctamente"));
              }
               else{
               FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_INFO, "Invalido", "Fecha invalida"));
                 }
            } catch (Exception e) {
                FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error", "Hubo un problema"));
            }
        }
Basil Bourque
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Sebastin Leyva Chumpitaz
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    Welcome to Stack Overflow! Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, _a specific problem or error_ and _the shortest code necessary_ to reproduce it **in the question itself**. Questions without a clear problem statement are not useful to other readers. See: [How to create a Minimal, Complete, and Verifiable example](http://stackoverflow.com/help/mcve). – Joe C Nov 23 '18 at 22:18
  • What doesn’t work? Is it `String fechaActual= String.valueOf(Calendar.DATE/Calendar.MONTH/Calendar.YEAR);` by any chance? – achAmháin Nov 23 '18 at 22:19
  • what I need is to extract the current date I thought I'd do it with:: String.valueOf (Calendar.DATE/Calendar.MONTH/Calendar.YEAR); – Sebastin Leyva Chumpitaz Nov 23 '18 at 22:21
  • Comparing String is going to give you character comparison. If you want to compare dates, you should use classes from the java.time package. – John Camerin Nov 23 '18 at 22:23
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    Check this question https://stackoverflow.com/questions/2592501/how-to-compare-dates-in-java – 11thdimension Nov 23 '18 at 22:29
  • I just edited my question – Sebastin Leyva Chumpitaz Nov 23 '18 at 22:32
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    Don’t use the `Calendar` class. It has design problems and is long outdated. Use [`java.time`, the modern Java date and time API,](https://docs.oracle.com/javase/tutorial/datetime/) and in particular its `LocalDate` class for a date without time of day and without time of day. Look into its `isBefore` or `isAfter` method. – Ole V.V. Nov 23 '18 at 22:32
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    FYI, the terribly troublesome old date-time classes such as [`java.util.Date`](https://docs.oracle.com/javase/10/docs/api/java/util/Date.html), [`java.util.Calendar`](https://docs.oracle.com/javase/10/docs/api/java/util/Calendar.html), and `java.text.SimpleDateFormat` are now [legacy](https://en.wikipedia.org/wiki/Legacy_system), supplanted by the [*java.time*](https://docs.oracle.com/javase/10/docs/api/java/time/package-summary.html) classes built into Java 8 and later. See [*Tutorial* by Oracle](https://docs.oracle.com/javase/tutorial/datetime/TOC.html). – Basil Bourque Nov 23 '18 at 22:37
  • I will take your comments and comments into account when working with dates, thank you very much. – Sebastin Leyva Chumpitaz Nov 23 '18 at 22:44

2 Answers2

1

The following lines are invalid and do not do what you think they should:

String fechaActual= String.valueOf(Calendar.DATE/Calendar.MONTH/Calendar.YEAR);        
String fechaPasada = "01/01/1970";
if(fechaPasada  > persona.getFechNac() <= fechaActual ){

It looks like you want to check that the value returned by persona.getFechNac() is a date after 01/01/1970 and before or equal to the current date.

The right way to do this is something like this:

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

// ...

LocalDate fechaActual = LocalDate.now();
LocalDate fechaPasada = LocalDate.of(1970, 1, 1);

LocalDate fechNac = LocalDate.parse(persona.getFechNac(),
                            DateTimeFormatter.ofPattern("dd/MM/yyyy"));

if (fechNac.isAfter(fechaPasada) && fechaActual.isBefore(fechNac)) {
    // ...
}

I'm assuming here that persona.getFechNac() returns a String containing a date in the format dd/MM/yyyy.

Jesper
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1

tl;dr

Use modern classes, specifically LocalDate.

LocalDate                                        // Represent a date-only value without a time-of-day and without a time zone or offset-from-UTC.
.parse(
    "21/01/1966" ,                               // String in some localized format. 
    DateTimeFormatter.ofPattern( "dd/MM/uuuu" )  // Specify formatting pattern to match input string.
)                                                // Returns a `LocalDate` object.
.isBefore(                                       // Compare one `LocalDate` to another.
    LocalDate.EPOCH                              // 1970-01-01
)                                                // Returns a boolean.

true

java.time

Use modern java.time classes only, never SimpleDateFormat or Calendar.

LocalDate

The LocalDate class represents a date-only value without time-of-day and without time zone or offset-from-UTC.

Parsing

Define a formatting pattern to match your input string.

String input = "01/01/1970" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ;
LocalDate limit = LocalDate.parse( input , f ) ;

Current date

Get today's date.

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment during runtime(!), so your results may vary. Better to specify your [desired/expected time zone][2] explicitly as an argument.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 2-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!). 

ZoneId z = ZoneId.of( "America/Montreal" ) ;  
LocalDate today = LocalDate.now( z ) ;

If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the JVM’s current default is applied implicitly. Better to be explicit, as the default may be changed at any moment during runtime by any code in any thread of any app within the JVM.

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

Compare

boolean isBeforeLimit = today.isBefore( limit ) ;  // Returns false.

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Basil Bourque
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