Java编程实现生成给定范围内不重复随机数的方法小结

package test;
import java.util.SortedSet;
import java.util.TreeSet;
public class MathRandom {
  static SortedSet set = new TreeSet();
  public static int randomSet(double m, double n) {
    int num = (int) m + (int) (Math.random() * (n - m));
    return num;
  }
  public static void shuangSe(int num1, int num2) {
    for (int i = 0; i < num1; i++) {
      set.add(randomSet(1, 33));
    }
    if (set.size() < num2) {
      shuangSe(num2 - set.size(), num2);
    }
  }
  public static void main(String[] args) {
    shuangSe(6, 6);
    System.out.print(set);
    System.out.println("  "+randomSet(1,16));
  }
}

[3, 13, 17, 21, 23, 25]  2

package test;
public class MathRandomChar {
  public static char getRandomChar(char c1,char c2){
    return (char)(c1+Math.random()*(c2-c1+1));
     }
  public static void main(String[] args) {
    System.out.println("a-z之间的任意字符:  "+getRandomChar('a','z'));
  }
}

a-z之间的任意字符:  g

package test;
import java.util.Random;
import java.util.SortedSet;
import java.util.TreeSet;
public class Test {
  static Random ran = new Random();
  static SortedSet set = new TreeSet();
  public static void randomSet(int n, int m) {
    for (int i = 0; i < n; i++) {
      set.add(ran.nextInt(33) + 1);
    }
    if (set.size() < m) {
      randomSet(m - set.size(), m);
    }
  }
  public static void main(String[] args) {
    randomSet(6, 6);
    System.out.print(set);
    System.out.println(" "+(ran.nextInt(16)+1));
  }
}

[1, 15, 18, 29, 30, 31] 13

package test;
import java.util.Random;
import java.util.Set;
import java.util.TreeSet;
public class ShuangSeQiu {
  public static void main(String[] args) {
    Random ran = new Random();
    Set<Integer> set = new TreeSet<>();
    while (true) {
      int a = ran.nextInt(33) + 1;
      set.add(a);
      if (set.size() > 5) {
        System.out.print(set);
        break;
      }
    }
    System.out.println(" "+(ran.nextInt(16)+1));
  }
}

[2, 11, 12, 16, 23, 26] 7