I'm having trouble using the random number generator, or having trouble understanding the concept entirely. I want to generate 20 random numbers from 0 to x.
Random ranNum= new Random();
int n = ranNum.nextInt(x) + 0;
Is this how I would go about it?
The following will create an ArrayList of values between 0 and x, inclusive, assuming that x has been previously defined as a positive int.
ArrayList<Integer> randNums = new ArrayList<Integer>();
Random r = new Random();
for(int i = 0; i < 20; ++i) {
randNums.add(r.nextInt(x + 1));
}
You can then use the values however you wish (printing or in subsequent calculations) by iterating through the ArrayList.
Run this code:
int x=100,n=0;
Random ranNum= new Random();
for(int i=0;i<20;i++)
{
n = ranNum.nextInt(x);
System.out.println(n);
}
X is the range of random number. this program generate random number between 0 to 100.If you want to specify a min value than you can try this line inside the loop:
n = ranNum.nextInt(x-min)+min;
With this you create 20 random numbers. I still didn't understand wheter you wanna have duplicates in your random numbers or not. Well, try this:
static Random r = new Random();
private static final int number = 5;
public static void main(String[] args) {
for(int i =0; i<20;i++){
System.out.println(r.nextInt(number));
}
}
Depends on what you need the numbers for.
To print them, you would:
Random randNum = new Random();
for(int x = 0; x < 20; x++){
System.out.println(randNum.nextInt(20));
}
Put in ArrayList and print out:
ArrayList<Integer> list = new ArrayList<Integer>();
Random randNum = new Random();
for(int x = 0; x < 20; x++){
list.add(randNum.nextInt(x)); //must set x to set maximum number it can be
}
for(int a : list)
System.out.println(a);
I like Math.random(), it returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.
public int getNumber(int max) {
return (int) (Math.random() * max); //returns an int between 0 and max
}
public void main() {
for(int i = 0; i < 20; i++) {
System.out.println(getNumber(100));
}
}
Prints 20 numbers between 0 and 100, for more info about Math.random() https://docs.oracle.com/javase/7/docs/api/java/lang/Math.html
getNumber method. The upper limit for Math.random() is not 0.9, and multiplying by max and casting to int will never yield max.
nextInt would be better, that's what it's for. Noting within your answer that things need to be handled differently depending on whether the upper bound is inclusive or exclusive would make it a better answer. Not putting in false statements such as Math.random() "returns a double between 0.0 and 0.9" would be best of all. for (int i = 0; i < 20; i++) {
double r = Math.random();
int[] RandomNumbers= new int[20];
RandomNumbers[i] = (int) (101. * r);
System.out.println(RandomNumbers[i]);
}
x? 3) What do you think is accomplished by adding zero? 4) Have you tried what you proposed? If not, why not, and if so, what did it not do that you were hoping to see?