randomgen.java

来自「一个TSP问题的图形演示程序」· Java 代码 · 共 46 行

/*
 *  This code is from the book:
 *
 *    Winder, R and Roberts, G (2000) Developing Java
 *    Software, second edition, John Wiley & Sons.
 *
 *  It is copyright (c) 2000 Russel Winder and Graham Roberts.
 */

package SimFrameWork ;
import java.util.Random ;
/**
 *  This is a utility class providing a wrapper for the JDK class
 *  java.util.Random, giving a simple interface to random number
 *  generation used by simulations.
 *  A single instance of the class is created and initialised
 *  when the class is loaded (an example of the Singleton pattern).
 *  If a more sophisticated generator is needed, this class
 *  will localize the effects of any changes made.
 *
 *  @version 2.0 March 1999
 *  @author Graham Roberts
 */
public class RandomGen {
  /**
   *  Do nothing constructor that is made private to prevent
   *  instance creation outside of the class scope.
   */
  private RandomGen() {}
  /**
   *  Generate a random integer in the range 0 to n-1 inclusive.
   *
   *  @param n the upper limit of the number generated.
   *  @return a random number in the range 0 to n-1.
   */
  public static int getNext(int n) {
    return rand.nextInt(n) ;
  }
  /**
   *  Variable used to represent the single instance.
   *  The Random class constructor will seed the random number
   *  generator automatically using the current time.
   */
  private static Random rand = new Random() ;
}