How to solve the seed problem in Java Random class

It can be said that in current computer languages ​​and ordinary users, there is no way to obtain true random numbers. True random numbers are now only available in quantum computers.

So the random numbers we are talking about now can also be called pseudo-random numbers. Pseudo-random numbers are the result obtained through an algorithm and combined with the next regularly changing number (such as time).

We call this data that is collected through algorithm time as the basis for initially obtaining random numbers as a seed.

There are two ways to create random numbers in Java:

The first is to directly create a Random object

Random random = new Random();

This method will be called at the bottom to get the seed :

The second is to pass the seed you created:

Random random = new Random(5);

In the source code we can directly It can be seen that the data type of the seed is long, which is a long integer.

So we now have a way to get the seed it generates when it first generates a Random object, and then pass the obtained seed into the object that created the Random. Is it possible to obtain the same random number as above?

First use the java language to implement it:

import java.util.Random;

public class Demo02 {
    public static void main(String[] args) {
        Random random = new Random(5);//在这将5作为种子传入
        System.out.println("第一次调用：");
        for (int i = 0; i < 5; i++) {
            System.out.print(random.nextInt(10) + "\t");
            //获得10以内的随机数(不包括10)
        }
        random.setSeed(5);//在这再将种子5传入Random的种子当中
        System.out.println("\n第二次调用：");
        for (int i = 0; i < 5; i++) {
            System.out.print(random.nextInt(10) + "\t");
        }
    }
}

It is obvious from here that this random number is not random at all. As long as the seed is the same twice, the same result will be returned.

Here I use python language to implement this function again (mainly because there is no method in Java that can call the output of the current seed). Use python to have a better understanding.

In python, I will write more detailed comments. The details will not be difficult to understand.

import random  #导入random内库
x = random.getstate()  # 获得当前random里的种子
print('第一次循环：') #输入语句
for i in range(5):
    #for循环  for i in range(5)  ===》 for (int i = 0; i < 5; i++)
    #在python里面并没哟什么大括号去吧什么括起来，而是要注意锁定，一个锁定就是一个整体
    print(random.randint(1, 10), end=&#39;\t&#39;)
    #random.randint(1, 10)生成1~10(不包括10)的随机数，
    # end=&#39;\t&#39;表示当前print没有结束，还有一个制表符的键位，也就不换行了
print(&#39;\n第二次循环&#39;)
random.setstate(x)#将上面获得的种子再次传入进去
for i in range(5): #这里和上面一样，循环出5次
    print(random.randint(1, 10), end=&#39;\t&#39;)

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