randomgenerator.java

《Java编程思想》第四版

//: net/mindview/util/RandomGenerator.java
// Generators that produce random values.
package net.mindview.util;
import java.util.*;

public class RandomGenerator {
  private static Random r = new Random(47);
  public static class
  Boolean implements Generator<java.lang.Boolean> {
    public java.lang.Boolean next() {
      return r.nextBoolean();
    }
  }
  public static class
  Byte implements Generator<java.lang.Byte> {
    public java.lang.Byte next() {
      return (byte)r.nextInt();
    }
  }
  public static class
  Character implements Generator<java.lang.Character> {
    public java.lang.Character next() {
      return CountingGenerator.chars[
        r.nextInt(CountingGenerator.chars.length)];
    }
  }
  public static class
  String extends CountingGenerator.String {
    // Plug in the random Character generator:
    { cg = new Character(); } // Instance initializer
    public String() {}
    public String(int length) { super(length); }
  }
  public static class
  Short implements Generator<java.lang.Short> {
    public java.lang.Short next() {
      return (short)r.nextInt();
    }
  }
  public static class
  Integer implements Generator<java.lang.Integer> {
    private int mod = 10000;
    public Integer() {}
    public Integer(int modulo) { mod = modulo; }
    public java.lang.Integer next() {
      return r.nextInt(mod);
    }
  }
  public static class
  Long implements Generator<java.lang.Long> {
    private int mod = 10000;
    public Long() {}
    public Long(int modulo) { mod = modulo; }
    public java.lang.Long next() {
      return new java.lang.Long(r.nextInt(mod));
    }
  }
  public static class
  Float implements Generator<java.lang.Float> {
    public java.lang.Float next() {
      // Trim all but the first two decimal places:
      int trimmed = Math.round(r.nextFloat() * 100);
      return ((float)trimmed) / 100;
    }
  }
  public static class
  Double implements Generator<java.lang.Double> {
    public java.lang.Double next() {
      long trimmed = Math.round(r.nextDouble() * 100);
      return ((double)trimmed) / 100;
    }
  }
} ///:~