面对对象 - java这段代码为什么不随机的

Question

在看Thinking in Java，有一段实在没看懂

package com.company.allAreTheObjective.Symbol;
import java.util.*;

/**
 * Created by Francis on 12/05/2016.
 */
public class VowelsAndConsonants {
    public static void main(String args[]){
        Random rand = new Random(47);
        for (int i = 0; i < 100; i++){
            int c = rand.nextInt(26) + 'a';
            System.out.print((char)c+","+ c +":");
            switch(c){
                case 'u' : System.out.println("vowel");break;
                case 'w' : System.out.println("Sometimes a vowel");break;
                default  : System.out.println("constant");
            }
        }
    }
}

这一段为什么输出恒为
y,121:constant
n,110:constant
z,122:constant
b,98:constant
r,114:constant
n,110:constant
y,121:constant

Answer 1

The program generates pseudo-random numbers. Your random number seed is fixed at 47. Of course, it will be the same every time. If you want it to be different, you can change the seed to a timestamp or something like that

Answer 2

Just put itnew Random(47)改成new Random().

The random numbers generated by the computer are all pseudo-random numbers. As long as the initialization seed given is the same, the generated random number sequence will be the same.

Answer 3

Random objects with the same seed number, the random numbers generated the same times are exactly the same.
Just change it to Random rand = new Random().