Caesar encryption. Array out of bounds in index 73 out of 73

Question

I am working on a caesar encryption code for a presentation in maths. Today, I have been coding for my presentation. In the morning this code has been working. But now at school, I get an exception which says, I think, that the for counts over the length of my symbols table.

The Exception:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: Index 73 out of bounds for length 73 at caesarForm.decrypt(caesarForm.java:81)

Line 81 is the 3rd for in decrypt()

I would be pleased if someone can look over my code because I, with my 3-month coding experience, can't understand what is going on.

//Alphanumeric table
    final static char[] symbs = new char[] {'.',',','1','2','3','4','5','6','7','8','9','0','/','z','y','x','w','v','u','t','s','r','q','p','o','n','m','l','k','j','i','h','g','f','e','d','c','b','a',' '
                    ,'ß','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','ä','ö','ü','Ü','Ö','Ä'};
    final static int charlength = 73;

    //var global key
    int key = 0;

    //en- and decryption vars
    char[] letters = new char[255];
    char[] storg = new char[255];
    char[] sterg = new char[255];
    StringBuilder str = new StringBuilder();
    int cnt = 0;
    int cnt2 = 0;
    int c = 0;
    String bakToStr;

textField1.addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent e) {
                super.keyTyped(e);
                char iNumber = e.getKeyChar();
                if (!(Character.isDigit(iNumber))
                        || iNumber == KeyEvent.VK_BACK_SPACE
                        || iNumber == KeyEvent.VK_DELETE) {
                    e.consume();
                    JOptionPane.showMessageDialog(contentPane, "Nur Zahlen werden als schlüssel akzeptiert", "Achtung!", JOptionPane.INFORMATION_MESSAGE);
                }
            }
        });

public String encrypt(String Text) {
        letters = new char[255];
        storg = new char[255];
        sterg = new char[255];
        str = new StringBuilder();
        cnt = 0;
        cnt2 = 1;
        c = 0;
        bakToStr = "";
        for (int i = 0; i <Text.length(); i++) {
            letters[i] = Text.charAt(i);
        }
        for (; cnt < Text.length(); cnt++) {
            for (;letters[cnt] != symbs[cnt2];cnt2++) {
            }
            c = (cnt2 + key) %charlength;
            storg[cnt] = symbs[c];
            cnt2 = 0;
        }
        str.append(storg);
        bakToStr = String.valueOf(str);
        return bakToStr;
    }

    public String decrypt(String Text) {
        letters = new char[255];
        storg = new char[255];
        sterg = new char[255];
        str = new StringBuilder();
        cnt = 0;
        cnt2 = 1;
        c = 0;
        bakToStr = "";
        for (int i = 0; i <Text.length(); i++) {
            letters[i] = Text.charAt(i);
        }
        for (; cnt < Text.length(); cnt++) {
            for (;letters[cnt] != symbs[cnt2];cnt2++) {
            }
            c = (cnt2 - key) %charlength;
            while (c <= 0) {
                c += charlength;
            }
            storg[cnt] = symbs[c];
            cnt2 = 0;
        }
        str.append(storg);
        bakToStr = String.valueOf(str);
        return bakToStr;
    }

Answer 1

I've found the problem:

StringBuilder str = new StringBuilder();

I don't know why, but without the Stringbuilder I don't get any problems anymore.

Thanks for Mohammed and @MadProgrammer for trying to help :)

Greets, Kazakh.