Please, no full code, we do not want people to copy/paste your code and not have as much fun as you had 
Just few tips:
If you can, write your variable names and your comments in English. When this is a personal/school/etc. project writing it in your own language is ok, but when you share it to on international community, you cannot expect them to understand easily your code if they can't read it.
You do not need to create 26 if statement to write a letter in lowercase (or uppercase). These are things that are really common and you can expect that it already exist. You can go on Google and search " lowercase", i'm sure you'll find what you need.
For your language, here is the documentation: http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#toLowerCase()
So instead of:
letbylet = T.split("");
for loop over each letter to put it in uppercase
you can do it in one line, writting:
letbylet = T.toUpperCase().split("");
As for your hashmap where each letter is associated to an integer giving its index (A -> 0, B -> 1, ..., Z -> 25), you can do the equivalent by creating the following function:
int indexOfLetter (String letter) {
return letter.charAt(0) - 'A';
}
As for your hashmap where each letter is associated to an integer giving its index (A -> 0, B -> 1, ..., Z -> 25), you can do the equivalent by creating the following function:As for your hashmap where each letter is associated to an integer giving its index (A -> 0, B -> 1, ..., Z -> 25), you can do the equivalent by creating the following function:
int indexOfLetter (String letter) {
return letter.charAt(0) - 'A';
}
This works because letter.charAt(0) return a Character, and 'A' is a Character (notice the single quotes). A Character is internally just its ASCII value. In ASCII 'A' is 65, 'B' is 66, ..., 'Z' is 90. so 'Z' - 'A' = 90 - 65 = 25.
This function would save you some lines, and you can add a comment for someone that would read your code and without knowing what happens when you subtract a Character to another Character.
Later in your code, I can see a try catch for a nullPointerException. You should avoid it when possible. Here you can try to better handle your variable to not compute something with a null.
It is hard for me to give you more comments on your code as I do not understand your variable.
By the way, we are working on a way to let you display your code to others on the platform. We would prefer that you wait this feature before publishing your code online (yes, I already said it in the beginning of the message, but it is really important to us).
