A software installation serial number of 20 characters is randomly generated.

Import java. util .*;
Public class gensn
{
Random objrandom;
Public gensn ()
{
Long seed = calendar. getinstance (). gettimeinmillis ();
Objrandom = new random (SEED );
}
Private char genchar ()
{
// The characters to be generated include 26 letters, 10 digits, and 36 characters in total
Int irand = objrandom. nextint (36 );
// Set 0 ~ A random number between 9, mapped to the corresponding number
If (irand <= 9)
Return (char) (irand + 48 );
Else
Return (char) (irand + 55 );
}
Public static void main (string ARGs [])
{
System. Out. Print ("serial number :");
Gensn OBJ = new gensn ();
For (INT I = 1; I <24; I ++)
{
If (I % 6! = 0)
System. Out. Print (obj. genchar ());
Else
System. Out. Print ("-");
}
System. Out. println ();
}
}

Note: Numbers 0 ~ The ASCII code of 9 is from 48 ~ 57. The ASCII code of uppercase letters ranges from 65 ~ 90.