this is a part of my code :
public static final int HAUTE_IMPORTANCE = 1;
public static final int MOYENNE_IMPORTANCE = 2;
public static final int FAIBLE_IMPORTANCE = 3;
private static int dernierIdAttribue = 0; 
private Date dateCreation = Date.dateDuJour();
private Date dateLimite; 
private String description;
private int niveauImportance;
private boolean acheve;
private int id;
public Todo (String description, Date dateLimite) throws TodoInvalideException{
    if ( dateLimite == null||dateCreation.estEgale(dateLimite) ||!dateCreation.estPlusRecente(dateLimite) && description != null && !description.isEmpty()){
    this.description = description;                      
    this.dateLimite = null;
    this.niveauImportance = FAIBLE_IMPORTANCE;
    acheve = false;
    dernierIdAttribue++;
    id = dernierIdAttribue;            
    } else{
        throw new TodoInvalideException("Erreur constructeur2");  
estPLusRecente & estEgale are 2 class method in class Date.