Question

众所周知的java中的random()方法获得的是“伪随机数”，在C++里可以用设置seed的方法

众所周知的java中的random()方法获得的是“伪随机数”，在C++里可以用设置seed的方法来获得“真的随机数(我觉得也是伪随机数，不过伪的比较真)”，但是java里这个方法似乎不能设置参数，求大神指导java怎么过得随机数。

Answer 1

你用的是Math.random()吗？
Math只是个方便使用的工具类，真正生成随机数的是java.util.Random这个类，Math里也是使用这个类，只不过是封装好方便调用而已。
public static double random()

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0. Returned values are chosen pseudorandomly with (approximately) uniform distribution from that range.
When this method is first called, it creates a single new pseudorandom-number generator, exactly as if by the expression new java.util.Random() This new pseudorandom-number generator is used thereafter for all calls to this method and is used nowhere else. This method is properly synchronized to allow correct use by more than one thread. However, if many threads need to generate pseudorandom numbers at a great rate, it may reduce contention for each thread to have its own pseudorandom-number generator.

java.util.Random这个类的构造函数本身就提供了seed参数，详见JAVA API

public Random(long seed)

Creates a new random number generator using a single long seed. The seed is the initial value of the internal state of the pseudorandom number generator which is maintained by method next(int).
The invocation new Random(seed) is equivalent to:
Random rnd = new Random();
rnd.setSeed(seed);

Parameters:
seed - the initial seed

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虽然是复制粘贴的，但是还有点用……

Answer 2

可能种子就是当前的时间

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……关键是怎么设置种子

追答

书上说java.util.Random类可以设置种子，以便产生2个一样的序列用于测试需要

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(。•﹃ •。)

可是怎么设置