1.简单使用：
Random random=new Random();
int a=random.nextInt();
System.out.println(a);-325078223
Process finished with exit code 0产生int类型范围内 -2147483648～2147483647 的随机整数。
Random random=new Random();
int a=random.nextInt(10);
System.out.println(a);产生0~9的随机整数。
2.产生任意范围的随机整数
Random random=new Random();
int a=random.nextInt(6)+5;
System.out.println(a);产生任意范围的随机整数,此处为5~10.
3.产生任意范围的随机小数
Random random=new Random();
double a=random.nextDouble();
System.out.println(a);0.11665258082938701
Process finished with exit code 0产生（0,1）范围的随机小数.
Random random=new Random();
double a=random.nextDouble()*1.5+1;
System.out.println(a);2.445836482596139
Process finished with exit code 0
产生任意范围的随机小数,此处为1~2.5,精确度为double默认的精确度.
Random random=new Random();
double a=random.nextDouble()*1.5+1;
BigDecimal bg = new BigDecimal(a);
double b = bg.setScale(1, BigDecimal.ROUND_HALF_UP).doubleValue();
System.out.println(b);1.9
Process finished with exit code 0产生任意范围的随机小数,此处为1~2.5.精确度为小数点后一位。
关于double精确度的内容请参考 java double的精确度控制 还没写。。。不要点
4.seed 种子的使用
Random random1 = new Random(100);
System.out.println(random1.nextInt());
System.out.println(random1.nextFloat());
System.out.println(random1.nextBoolean());
Random random2 = new Random(100);
System.out.println(random2.nextInt());
System.out.println(random2.nextFloat());
System.out.println(random2.nextBoolean());-1193959466
0.7346627
false
-1193959466
0.7346627
false
Process finished with exit code 0相同种子输出的结果相同.
Random random1 = new Random(System.currentTimeMillis());
System.out.println(random1.nextInt());
System.out.println(random1.nextFloat());
System.out.println(random1.nextBoolean());
System.out.println();
Random random2 = new Random(System.currentTimeMillis());
System.out.println(random2.nextInt());
System.out.println(random2.nextFloat());
System.out.println(random2.nextBoolean());-1674565819
0.2528978
false
-1664947096
0.5270924
true
Process finished with exit code 0不同种子输出的结果不同.