Gwendal in main : add test on futur constraints and enhance input symbol method (#1)

Co-authored-by: ROGER <gwendal.roger@etu.univ-lyon1.fr>
Reviewed-on: #1

app/src/main/java/sudoku/Symbole.java

@@ -20,6 +20,19 @@ public class Symbole {
         return new Symbole(String.valueOf(c));
     }
 
+    public boolean isInt() {
+        try {
+            Integer.parseInt(valeur);
+            return true;
+        } catch (NumberFormatException e) {
+            return false;
+        }
+    }
+
+    public boolean isLetter() {
+        return valeur.length() == 1 && Character.isLetter(valeur.charAt(0));
+    }
+
     @Override
     public String toString() {
         return valeur;
@@ -27,8 +40,11 @@ public class Symbole {
 
     @Override
     public boolean equals(Object obj) {
-        if (this == obj) return true;
-        if (obj == null || getClass() != obj.getClass()) return false;
+        if (this == obj)
+            return true;
+
+        if (obj == null || getClass() != obj.getClass())
+            return false;
         Symbole symbole = (Symbole) obj;
         return valeur.equals(symbole.valeur);
     }