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Section 3.3 Worked Example: Create Instance of Random

Subgoals for using objects (creating instances).

  1. Declare variable of appropriate class datatype.
  2. Assign to variable: keyword new, followed by class name, followed by ().
  3. Determine whether parameter(s) are appropriate (API)
    1. Number of parameters
    2. Data types of the parameters

Subsection 3.3.1

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The following Java code declares and instantiates a variable that will be used to generate random values.

Subsection 3.3.2 SG1: Declare variable of appropriate class datatype.

In the code block below, the variable name randGen was selected to better describe this object’s purpose as a random number generator. 
Random randGen;

Subsection 3.3.3 SG2: Assign to variable:  keyword new, followed by class name, followed by (). 

randGen = new Random();

Subsection 3.3.4 SG3: Determine whether parameter(s) are appropriate (API)

The figure below shows the Java documentation, so we can determine what parameter(s) we need. If we wanted a specific seed value, we could use that, but for most purposes, allowing the constructor to select its own seed is ok.
Figure 3.3.1.
So the final code looks like this: 
Random randGen;
randGen = new Random();
Notice in the ActiveCode box below, we have added the appropriate import statement for using the Random class.

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