Java: do something x percent of the time

Question

I need a few lines of Java code that run a command x percent of the time at random.

psuedocode:

boolean x = true 10% of cases.

if(x){
  System.out.p         


        

Answer 1

public static boolean getRandPercent(int percent) {
    Random rand = new Random();
    return rand.nextInt(100) <= percent;
}

Answer 2

If by time you mean times that the code is being executed, so that you want something, inside a code block, that is executed 10% of the times the whole block is executed you can just do something like:

Random r = new Random();

...
void yourFunction()
{
  float chance = r.nextFloat();

  if (chance <= 0.10f)
    doSomethingLucky();
}

Of course 0.10f stands for 10% but you can adjust it. Like every PRNG algorithm this works by average usage. You won't get near to 10% unless yourFunction() is called a reasonable amount of times.

Answer 3

You can use Random. You may want to seed it, but the default is often sufficient.

Random random = new Random();
int nextInt = random.nextInt(10);
if (nextInt == 0) {
    // happens 10% of the time...
}

Answer 4

You just need something like this:

Random rand = new Random();

if (rand.nextInt(10) == 0) {
    System.out.println("you got lucky");
}

Here's a full example that measures it:

import java.util.Random;

public class Rand10 {
    public static void main(String[] args) {
        Random rand = new Random();
        int lucky = 0;
        for (int i = 0; i < 1000000; i++) {
            if (rand.nextInt(10) == 0) {
                lucky++;
            }
        }
        System.out.println(lucky); // you'll get a number close to 100000
    }
}

If you want something like 34% you could use rand.nextInt(100) < 34.

Answer 5

You have to define "time" first, since 10% is a relative measure...

E.g. x is true every 5 seconds.

Or you could use a random number generator that samples uniformly from 1 to 10 and always do something if he samples a "1".

Answer 6

You could always generate a random number (by default it is between 0 and 1 I believe) and check if it is <= .1, again this is not uniformly random....