Randomness

You know what's cool? Having the computer randomly choose a number. This is the basis of pretty much every computer game ever. To pick a random number, you first need to import java.util.Random; Then, you must create a random-number generator object, like so:

Random rnd = new Random();

Once that's finished, you can have the computer pick a random integer like this:

int x = 1 + rnd.nextInt(100);

That picks a random number from 1 to 100 (inclusive) and store it into the variable x. Let's look at some code!

import java.util.Random;

public class RandomGenerator{

    public static void main(String []args)
    {
        output("Generate 10 random integers between 0 and 99");

        Random rnd = new Random();

        for (int i = 1; i <= 10; ++i)
        {
          int randomInt = 1 + rnd.nextInt(100);
          output("Generated number: " + randomInt);
        }

        output("Done.");
    }

  private static void output(String aMessage)
  {
    System.out.println(aMessage);
  }
}

1. Delete the 1 + from the line that reads int randomInt = 1 + rnd.nextInt(100);.Run the program to see what this does to the range of the random numbers.
2. Change the 1 + from the line that read int randomInt = 1 + rnd.nextInt(100); to 5 +. What happens?
3. Change the line where you create the random number generator so that it looks like this: Random r = new Random(23456); This number is called a seed. Run the program a few times. What happens?
4. Change to random seed to something else. What happens?
5. If you cast a number to a (char) then the character representation of that number will be printed. Create a password generator that casts 8 random numbers between 40 and 126 to characters.