Math class Random class

java.lang.Math    

A bunch of mathematical methods

/ * Member method

    * Public static int ABS (int A) 
    * public static Double ceil (Double A) 
    * public static Double Floor (Double A) 
    * public static int max (int A, int B) min Self 
    * public static double pow (double a , double b) // a, b th 
    * public static double random () 
    self * public static int round (float a ) rounding of double parameter 
    * public static double sqrt (double a ) the square root of 
* /

Math.random (): returns greater than or equal  0.0 to less than  1.0 a pseudo-random  double value.

 

Random category

　　　Random r = new Random();

　　　int x = r.nextInt (); // generates a random number

 

　　    int y = r.nextInt (100); // generates a random 0-99 wherein a   

　　　　 Math.random () more convenient to use

/*

* A: Random Class The 
    * type for generating a random number if the Random creates two instances with the same seed, 
    * for each instance of the same sequence of method calls, which will generate and return the same sequence of numbers. 
* B: Constructor 
    * public Random () 
    * public Random (Long the SEED) // use a seed to generate random numbers 
* C: member method 
    * public int nextInt () 
    * public int nextInt (the n-int) (master key) 
* /