Calculates and returns a random integer array with Min as the upper limit of Max.

Import java. util. arrays;
Import java. util. Random;

/**
* <Code> randomutil </code>-random tool class.
* @ Author sagezk
* @ Version 1.0
*/
Public class randomutil {

Private randomutil (){}

Private Static random RND = NULL;

/**
* Initialize the random number generator.
*/
Private Static void initrnd (){
If (RND = NULL) RND = new random ();
}

/**
* Calculates and returns a random integer array with <code> min </code> as the lower <code> max </code> as the upper limit.
* @ Param min minimum random INTEGER (inclusive)
* @ Param Max random integer upper limit (inclusive)
* @ Param Len result array Length
* @ Return result Array
*/
Public static int [] getlotteryarray (INT min, int Max, int Len ){
// Parameter verification and performance optimization
If (LEN <0) return NULL; // The array with a length less than 0 does not exist.
If (LEN = 0) return New int [0]; // returns an array with a length of 0
If (min> MAX) {// calibration parameter min max
Int T = min;
Min = max;
Max = T;
}
Final int Len = max-min + 1; // Number of Seeds
If (LEN> Len) return NULL; // If 35 or 36 appears, null is returned.
// Calculate a random array without repeated values
Initrnd (); // initialize the random number generator
Int [] seed = new int [Len]; // seed Array
For (INT I = 0, n = min; I <Len;) seed [I ++] = n ++; // initialize the seed Array
For (INT I = 0, j = 0, T = 0; I <Len; ++ I ){
J = RND. nextint (LEN-I) + I;
T = seed [I];
Seed [I] = seed [J];
Seed [J] = T;
}
Return arrays. copyof (seed, Len); // Note: copyof requires jre1.6
}

// Unit Testing
Public static void main (string [] ARGs ){
Final int n = 10000; // number of tests
For (INT I = 0; I <n; ++ I ){
Int [] La = randomutil. getlotteryarray (1, 35, 7 );
If (La = NULL) continue;
For (int v: La) system. Out. printf ("% 0 $ 02d", V );
System. Out. println ();
}
}

}