D.9.1. Scaling and Shifting of Random Numbers

To demonstrate random numbers, let’s show to simulate rolling a six-sided die. We begin by using nextInt to produce random values in the range 0–5, as follows:

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The argument 6—called the scaling factor—represents the number of unique values that nextInt should produce (in this case six—0, 1, 2, 3, 4 and 5). This manipulation is called scaling the range of values produced by Random method nextInt.

A six-sided die has the numbers 1–6 on its faces, not 0–5. So we shift the range of numbers produced by adding a shifting value—in this case 1—to our previous result, as in

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The shifting value (1) specifies the first value in the desired range of random integers. The preceding statement assigns face a random integer in the range 1–6. The numbers produced by nextInt occur with approximately equal likelihood.