Generating Random Doubles in Java

double, java

Solution

Try this:

    Random r = new Random(); 
    double d = -10.0 + r.nextDouble() * 20.0;

Note: it should be 20.0 (not 21.0)

Problem

I'm a Java noob trying to generate a random double between -10 and 10 inclusive. I know with ints I would do the following: ``` Random r = new Random(); int i = -10 + r.nextInt(21); ``` However, with doubles, this doesn't work: ``` Random r = new Random(); double i = -10 + r.nextDouble(21); ``` Can someone please explain what to do in the case of doubles?

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