java 随机数

http://www.kirun.co.uk/java/answers/33.php
Random Numbers

The method you need to use isMath.Random();. This produces a random number from 0 to 1. To make this useful, you need to multiply by the range, and add the lowest number.

int thing = (int)(Math.random()*5);This produces a whole random number from 0 to 4
int thing = (int)(Math.random()*10+1);This produces a whole random number from 1 to 10
double thing = (Math.random()*5+1);This produces a real random number from 1 to 5

Random numbers aren't actually random, but are generated by complicated maths.

If you need a random sequence that is the same every time the program is run, then the Random class is more useful.

static Random bob = new Random(); Creates a new Random() object.
bob.setSeed(12345); Sets a seed, of type long ***check long*** + coding
System.out.println("The next random number is :" + bob.nextDouble());
System.out.println("The one after that is :" + bob.nextDouble());

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