/*** Encodes a decimal value to a Base62 <code>String</code>.* * @param b10*            the decimal value to encode, must be nonnegative.* @return the number encoded as a Base62 <code>String</code>.*/public String encodeBase10(long b10) {if (b10 < 0) {throw new IllegalArgumentException("b10 must be nonnegative");}String ret = "";while (b10 > 0) {ret = characters.charAt((int) (b10 % 62)) + ret;b10 /= 62;}return ret;}

    /*** Decodes a Base62 <code>String</code> returning a <code>long</code>.* * @param b62*            the Base62 <code>String</code> to decode.* @return the decoded number as a <code>long</code>.* @throws IllegalArgumentException*             if the given <code>String</code> contains characters not*             specified in the constructor.*/public long decodeBase62(String b62) {for (char character : b62.toCharArray()) {if (!characters.contains(String.valueOf(character))) {throw new IllegalArgumentException("Invalid character(s) in string: " + character);}}long ret = 0;b62 = new StringBuffer(b62).reverse().toString();long count = 1;for (char character : b62.toCharArray()) {ret += characters.indexOf(character) * count;count *= 62;}return ret;}

    public static void main(String[] args) {Base62 encoder=new Base62();Long time=System.nanoTime();String timeStr=encoder.encodeBase10(time);System.out.println(timeStr);System.out.println(time);System.out.println(encoder.decodeBase62(timeStr));}

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613534552694770
613534552694770