Java - create an Array and ArrayList

Question

Hi I’m pretty new to java and I’m still learning.
How can I create an array of 10 random Rational numbers (ex:between 1 to 50) and create an ArrayList containing the 10 Rational numbers.

Answer 1

There are different methods to create a random number. (Google java random)
Normally I use this:

import java.util.Random;
Random r = new Random ();
int randomNum = r.nextInt (50) + 1;
//creates a number between 1 - 50

To create an Array:

int [] num = new int [10];

Fill the array with a loop:

for (int i = 0; i < num.length; i++){
randomNum = r.nextInt (50) + 1;
num [i] = randomNum;
}

edit: I didn't see that you want rational numbers --> double or float
double num = r.nextDouble should work or use Math.random ()

Answer 2

Arraylist:

import java.util.ArrayList;

ArrayList nums = new ArrayList();

for (int i = 0; i < 10; i++){
//create randomNum
nums.add (randomNum);
}

Answer 3

Hi,

Have a look at the Java standard library. You can find documentation of both generating random numbers and creating ArrayLists :) good luck!

//Johan