• Understand Java Random
  • Understand the details of declaring variables, allocating objects, and using objects of type Random.
  • Understand Java Random has a set of values and a set of operations.
  • Understand how to call Randome instance methods
  • Java Random

    We have used Math.random to generate a random numbers. In this section, we learn the Random class, which can be used to generate random numbers. To do this we have to declare a variable of type Random, allocate a Random object, and then call instance methods. The Random class is in the java.util package so you have to import java.util.Random. The following code snippet demonstrates how to create a variable of type Random, allocate a Random object, and call the methods.

    import java.util.Random;  // must be at the top of your .java file
    Random generator = new Random(42); // seed get same stream for testing
    int i = generator.nextInt(n); // 0 <= i < n
    double x = generator.nextDouble(); // 0 <= x < 1

    nextInt and nextDouble are Random object instance methods. What is the Math.random() method? It is a static method in the Math class. We will study the differences between instance and static in Classes and Objects.

    Seeding a Random object results in the same stream of random numbers each time a program is executed.

    Random Number Pattern

    The Random Number Pattern uses a Random object and Math.random to generate a random int and double.

    Tags: object class