get Random in ArrayList has error of java.lang.IllegalArgumentException: n must be positive
- by gabrielle fregil
In my ArrayList, i have get a random Item from my ArrayList for the equip method.
Whenever i use my tester, the terminal window prints java.lang.IllegalArgumentException: n must be positive when I try to call random for the size.
I tried to change the value of totalElements to the integer size of the elements, then the error would be an OutOfBoundsExeption
import java.util.*;
import java.util.Scanner;
import java.util.Random;
public class GameMaster {
private int turn, totalElements;
private boolean winner;
private Avatar x1;
private Avatar x2;
private ArrayList<Item> inventory;
public GameMaster(Avatar a1, Avatar a2)
{
x2 = a1;
x1 = a2;
turn = 1;
winner = false;
inventory = new ArrayList<Item>();
totalElements = 0;
}
private void fillInventory()
{
inventory.add( new Item( "Zealot Blades", true, 8 ) );
inventory.add( new Item( "BFG", true, 13 ) );
inventory.add( new Item( "Synthetic Cloth", false, 7 ) );
// more items
inventory.add( new Item( "Gauss Rifle", true, 9 ) );
inventory.add( new Item( "Flight Unit", false, 6 ) );
totalElements = inventory.size();
}
public String equip()
{
Avatar w;
String a;
if (turn%2==1)
w=x2;
else
w=x1;
if (w.beltIsFull())
{
a = w.getName() + "'s belt is full. \n";
}
else
{
turn++;
Random generator = new Random();
Item rand = inventory.get(generator.nextInt(totalElements));
//terminal window in blueJ: java.lang.IllegalArgumentException: n must be positive
a = w.getName()+" is equiped with "+rand.getName()+".";
}
return a;
}
