Prefer using `RandomGenerator#nextInt(source, bound)` over more contrived alternatives

[mohamedsamehsalah]

Problem

Before Java 17, java.util.Random#nextInt did not have a way to specify both a start and an end point. You could only specify the upper bound (the size of the range). To get a number between 20 and 99, you had to do the math manually:

// Calculate the range size: 100 - 20 = 80.
// Generate a random number between 0 and 79 using nextInt(80).
// Add the base offset (20) to that result.
Random random = new Random();

int randomPart = 20 + random.nextInt(80); // Returns a number from 20 to 99

Description of the proposed new feature

Now, with RandomGenerator, you can use the new #nextInt(origin, bound API to do this in a more idiomatic manner:

Random random = new Random();

int randomPart = random.nextInt(20, 100); // Returns a number from 20 to 99

• Support a stylistic preference.
• Avoid a common gotcha, or potential problem.
• Improve performance.

I would like to rewrite the following code:

a + random.nextInt(b)

to:

random.nextInt(a, a + b)

Considerations

Participation

• I am willing to submit a pull request to implement this improvement.

[mohamedsamehsalah]

Assigned to @szumal

[pzygielo]

I fail to understand that example for doing it manually:

int randomPart = random.nextInt(20 + random.nextInt(80)); // Returns a number from 20 to 99

This (the second [first in code] .nextInt call) seems to pick a number from 0 (to 19-99) again.

Which only shows that may be hard task to do indeed.

[mohamedsamehsalah]

@pzygielo my bad, I updated fixed the description.

Edit: Added another fix.