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Utils for Java

There is a newer version: 3.3.4

package wf.utils.java.math;


public enum Encoder {

        DIGITS("0123456789"),
        LOWER_LETTERS("abcdefghijklmnopqrstuvwxyz"),
        UPPER_LETTERS("ABCDEFGHIJKLMNOPQRSTUVWXYZ"),
        SPECIAL_SYMBOLS(".<>!()~-_\""),

        RADIX_10(DIGITS.getSymbols()),
        RADIX_36(RADIX_10.getSymbols() + LOWER_LETTERS.getSymbols()),
        RADIX_62(RADIX_36.getSymbols() + UPPER_LETTERS.getSymbols()),
        RADIX_72(RADIX_62.getSymbols() + SPECIAL_SYMBOLS.getSymbols());

        private final String symbols;

        Encoder(String symbols) {
            this.symbols = symbols;
        }


        public String encode(long l) {
            return encode(l, this);
        }

        public long decode(String s) {
            return decode(s, this);
        }

        public boolean isValid(String s) {
            return isValid(s, this);
        }


        public static String encode(long l, Encoder encoder) {
            String symbols = encoder.getSymbols();

            StringBuilder sb = new StringBuilder();
            while (l > 0) {
                sb.append(symbols.charAt((int) (l % symbols.length())));
                l /= symbols.length();
            }
            return sb.reverse().toString();
        }

        public static long decode(String s, Encoder encoder) {
            String symbols = encoder.getSymbols();

            long result = 0;
            for (int i = 0; i < s.length(); i++) {
                char c = s.charAt(i);
                int digit = symbols.indexOf(c);
                result = result * symbols.length() + digit;
            }
            return result;
        }

        public static boolean isValid(String s, Encoder encoder) {
            String allowedSymbols = encoder.getSymbols();

            for (int i = 0; i < s.length(); i++) {
                char c = s.charAt(i);
                if (allowedSymbols.indexOf(c) == -1) {
                    return false;
                }
            }
            return true;
        }

    public String getSymbols() {
        return symbols;
    }
}