CSIS 110 - Lecture 21 Announcements: Read Chapter 5, sections 5.1 to 5.4. Let's discuss the programming assignment any questions? I have your midterm grades if you want them, or you can wait until next week to look them up on WebOpus. No class next Friday (Oct 20)! Random Numbers In the real world, some things occur randomly, such as: flipping coins, rolling dice, atomic decay. What are some other situations where randomness occurs or is useful? games simulations controlled experiments lottery We'd like to be able to write programs that can do these sorts of things, but the programs must have a source of random behavior. So far, every program we have seen does the same thing every time it is run if it starts with the same data. Java includes a class named Random. Let's go look it up. Open BlueJ go look it up in the Java documentation. (Help | Java Class Libraries ). What package is it contained in? (That is, where do you need to tell Java to look for the Random class in an import statement?) How do you create an instance of a Random? How do you generate a random number? - create an instance of class Random - call a method on that object to get a number Open the random project (in chapter 5 directory). Go ahead and play around with it. What do the methods do? What is the difference between the two versions of printTenRandoms? Let's look at the code in a little more detail... Instance variable: a <a href="/keyword/random-number-generator/" >random number generator</a> Constructor: Initialize the <a href="/keyword/random-number-generator/" >random number generator</a> Methods: use the <a href="/keyword/random-number-generator/" >random number generator</a> to create random numbers. randomGenerator.nextInt() randomGenerator.nextInt( max ) Let's say that we wanted to use a <a href="/keyword/random-number-generator/" >random number generator</a> to simulate rolling a single die. What values do we need to generate? How would we do this? Lab Exercise You can either create a new project or use your DNA manipulation project from the last lab. Create a new class named Generate. You need to write one method in this class: public String generateDNA() This method needs to generate and return a random DNA sequence. The sequence must have a random length ranging from 1 to 20. Each character in the sequence must be a valid DNA character ('A', 'G', 'T', or 'C'). Use a <a href="/keyword/random-number-generator/" >random number generator</a> to determine how long to make the String. Use the same <a href="/keyword/random-number-generator/" >random number generator</a> to randomly select the characters in the String. The method must return a different DNA sequence each time it is called. Email the file Generate.java to me use the subject &quot;Lab 17&quot;. Lab Exercise You can either create a new project or use your DNA manipulation project from the last lab. Create a ...