pa help po sa error ko

[sleepsteal]

Gumagawa po kase ako ng random number generator na may operations sa java. netbeans po gamit ko. eto po ung code:

package randomgenerator;

import java.util.Random;
import java.util.Scanner;


public class RandomGenerator {


public static void main(String[] args) {

Random rand = new Random();
Scanner answer = new Scanner(System.in);

int number1 = rand.nextInt(0)+1;
int number2 = rand.nextInt(9)+1;
int num = rand.nextInt(4)+1;
int userAnswer;
int result;
char operator;


for (int counter = 0; counter <=10; counter ++){

switch (num)
{
case 1: operator = '+';
break;
case 2: operator = '-';
break;
case 3: operator = '*';
break;
case 4: operator = '/';
break;

}

if (num == 1)
{
System.out.print(counter + ". " + number1 + "+" + number2 + "=" );
userAnswer = answer.nextInt();
result = number1 + number2;
if (userAnswer == result)
{
System.out.println("Correct!! \n");
}
else
{
System.out.println("Incorrect!! \n");
}


}

if (num == 2)
{
System.out.print(counter + ". " + number1 + "-" + number2 + "=" );
userAnswer = answer.nextInt();
result = number1 - number2;
if (userAnswer == result)
{
System.out.println("Correct!! \n");
}
else
{
System.out.println("Incorrect!! \n");
}


}

if (num == 3)
{
System.out.print(counter + ". " + number1 + "*" + number2 + "=" );
userAnswer = answer.nextInt();
result = number1 * number2;
if (userAnswer == result)
{
System.out.println("Correct!! \n");
}
else
{
System.out.println("Incorrect!! \n");
}


}

if (num == 4)
{
System.out.print(counter + ". " + number1 + "/" + number2 + "=" );
userAnswer = answer.nextInt();
result = number1 / number2;
if (userAnswer == result)
{
System.out.println("Correct!! \n");
}
else
{
System.out.println("Incorrect!! \n");
}


}
}

}

}

eto nmn po ung error:


run:

Exception in thread "main" java.lang.IllegalArgumentException: bound must be positive
at java.util.Random.nextInt(Random.java:388)
at randomgenerator.RandomGenerator.main(RandomGenerator.java:15)
C:\Users\User\AppData\Local\NetBeans\Cache\8.2\executor-snippets\run.xml:53: Java returned: 1
BUILD FAILED (total time: 0 seconds)

TIA mga sir