I've been looking for a simple Java algorithm to generate a pseudo-random alpha-numeric string. In my situation it would be used as a unique session/key identifier that would "likely" be unique over 500K+ generation (my needs don't really require anything much more sophisticated).
Ideally, I would be able to specify a length depending on my uniqueness needs. For example, a generated string of length 12 might look something like "AEYGF7K0DM1X".
You can use an Apache Commons library for this, RandomStringUtils:
RandomStringUtils.randomAlphanumeric(20).toUpperCase();
Here it is in Java:
import static java.lang.Math.round;
import static java.lang.Math.random;
import static java.lang.Math.pow;
import static java.lang.Math.abs;
import static java.lang.Math.min;
import static org.apache.commons.lang.StringUtils.leftPad
public class RandomAlphaNum {
public static String gen(int length) {
StringBuffer sb = new StringBuffer();
for (int i = length; i > 0; i -= 12) {
int n = min(12, abs(i));
sb.append(leftPad(Long.toString(round(random() * pow(36, n)), 36), n, '0'));
}
return sb.toString();
}
}
Here's a sample run:
scala> RandomAlphaNum.gen(42)
res3: java.lang.String = uja6snx21bswf9t89s00bxssu8g6qlu16ffzqaxxoy