java1 random number class Random class

This Random class, which can generate random numbers of various data types, here we mainly introduce the way to generate integers and decimals.

1  Method introduction
 2  public  int nextInt( int maxValue) Generate random integers in the range of [ 0 , maxValue), including 0, excluding maxValue;
 3  public  double nextDouble() Generate random decimals in the range of [ 0 , 1 ), including 0. 0 , excluding 1. 0 .

1  How to use Random:
 2  Import package: the package java.util.Random belongs to  
 3 Create instance format: Random variable name = new Random();

RandomDemo.java code demo:

1  /* 
2      The existing reference type Random class in java, function, generate random numbers
 3      steps:
 4        1. Import the package, Random class, also in the java.util folder5
 2.        Formula: Create a variable of type
 Random6        3. Variables. Call the function in the Random class to generate a random number
 7        
8        Random class provides a function, the name nextInt() generates a random number, the result is the range of random numbers in the int type
 9        , in the function nextInt (write an integer) , Integer: Random number in the range of
 10. The range        of random numbers is between 0 - the specified integer nextInt(100) [0,99)
 11        
12        The random number generated by floating point: function name nextDouble() The range of random numbers [0.0,1.0)
 13        
14        Random number: pseudo-random number, generated by the virtual machine according to an algorithm written by a human.
 15  */ 
16  import java.util.Random;
 17 public  class RandomDemo{
 18      public  static  void main(String[] args){
 19         //     2. Formula: create a variable of type Random 
20         Random ran = new Random();
 21         // 3. Variable. Call the Random class Function to generate random numbers
 22         // In the Random class, the function to generate random numbers 
23         int i = ran.nextInt(100 );
 24         System.out.println(i);
 25         // Problem? Generate random numbers, range 1 26         between -100
 // nextInt(100) 0-99 + 1 
27         
28         double d = ran.nextDouble();
 29        System.out.println(d);       
30     }
31 }

Here we focus on generating random numbers in a specified range:

int ranNumber =ran.nextInt(max - min + 1) + min; // ranNumber will be assigned a random number in the range of min and max [min,max]

 // Generate random numbers within the specified range in java
 // int ranNumber =ran.nextInt(max - min + 1) + min; // ranNumber will be assigned a random number within the range of min and max [min,max]
 // For example: generate a random number between [155,658] 
int ranNumber = ran.nextInt(504) + 155 ;
System.out.println(ranNumber);

java1 random number class Random class

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