AP Computer Science Java: Lesson 3.4 Repetitive Statements - Random Integers Karel Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Progs Tests Back to Lesson 3.3 - Counts and Sums On to Lesson 3.5 - The while Loop Lesson 3.4 - Random Integers Purpose: To learn how to declare and use a random integer generator If you can't beat 'em, random!  The use of randomness has numerous applications from video games to computerized simulations. In Java, there are a few ways to generate random integers. We will use the random method from Java's Math class. The Math class random method is used as follows :    double x = Math.random(); //random decimal from 0-1    OR Generate a random number and display it without storing the value:    System.out.println( Math.random() ); To generate a random integer from 0 to n-1:    int y = (int) (n * Math.random()); OR more usefully, we generate a random integer from 1 to n:    int y = (int) (n * Math.random()) + 1; In general, to generate a random integer between a and b:    int y = (int) ((b-a+1) * Math.random()) + a;   In closing, The Math class random method generates decimal values. To get the necessary integer for a program, use the appropriate formula as follows:      1.  0 to n-1 : (int) (n * Math.random())      2.  1 to n   : (int) (n * Math.random()) + 1      3.  a to b   : (int) ((b-a+1) * Math.random()) + a Back to Lesson 3.3 - Counts and Sums On to Lesson 3.5 - The while Loop AP Home Karel Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Progs Tests