Urgent help

SellingJuan

Test 2mro, kinda need help. It says

"java.lang.ArrayIndexOutOfBoundsException:10"

I cant see where is going wrong.



import java.lang.Math;
import javax.swing.JOptionPane;
public class WK912

{
public static void main(String [] args)

{
int numberofnumbers, odd, aNumber, sum= 0, even= 0, neven = 0, max = 0, min = 0;
String ofnumbers= " ";
double avg = 0.0;
int [] numbers = new int [10];

for(int counter = 0; counter < numbers.length; counter ++)
{
aNumber = (int) ((Math.random () *70)+20);
numbers[counter] = aNumber;
sum += aNumber;
ofnumbers += aNumber + ", ";
}
avg = (sum/numbers.length);
for(int counter = 0 ; counter < numbers.length; counter++)
{
if(numbers[counter] % 2 ==0)
{
even +=1;

}
else
{
neven +=1;
}

}
int counter1 = 0;
max = numbers[0];
for( counter1 = 0; counter1 < numbers.length; counter1 ++);
{
if(numbers[counter1] > max)
{
max = numbers[counter1];
}

}

min = numbers[0];
for( counter1 =0; counter1 < numbers.length; counter1++)
{
if(numbers[counter1] < min)
{
min = numbers[counter1];
}
}

JOptionPane.showMessageDialog(null, ofnumbers + "\n The average is " + avg + "\n The sum is " + sum + "\n There are " + even + "numbers" + "\n There are " + neven + " numbers" + max + " " + min);
}
}

yoyo

Moved to Development

Esel

Did you get a line number where the exception is occurring?

http://www.google.ie/#hl=en&sugexp=les%3B&gs_nf=3&cp=43&gs_id=7&xhr=t&q=java.lang.ArrayIndexOutOfBoundsException%3A10&pf=p&output=search&sclient=psy-ab&oq=java.lang.ArrayIndexOutOfBoundsException:10&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=871f43a5ac29f5dc&bpcl=37189454&biw=1366&bih=665

SellingJuan

Esel wrote: »

Did you get a line number where the exception is occurring?

http://www.google.ie/#hl=en&sugexp=les%3B&gs_nf=3&cp=43&gs_id=7&xhr=t&q=java.lang.ArrayIndexOutOfBoundsException%3A10&pf=p&output=search&sclient=psy-ab&oq=java.lang.ArrayIndexOutOfBoundsException:10&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=871f43a5ac29f5dc&bpcl=37189454&biw=1366&bih=665

it said
39

SellingJuan

I have it working now, all I did was change counter to =1



But that shouldnt have been the problem like

Esel

Is this line 39? (presumably blank lines are counted?)

if(numbers[counter1] > max)

I actually don't know Java, just trying to help you as you've got a deadline.....

smokiebeverage

check the ; on line 37

for( counter1 = 0; counter1 < numbers.length; counter1 ++);

Esel

smokiebeverage wrote: »

check the ; on line 37

for( counter1 = 0; counter1 < numbers.length; counter1 ++);

Interesting that line 22 (similar code) has

for(int counter = 0 ; counter < numbers.length; counter++)

Is the absence of int the problem?

cgarvey

smokiebeverage wrote: »

check the ; on line 37

Yup, that's the problem. The effect is that the for loop has run 10 times before it ever gets to the next line (38), by which time counter1 is now 10.

smokiebeverage

cgarvey wrote: »

Yup, that's the problem. The effect is that the for loop has run 10 times before it ever gets to the next line (38), by which time counter1 is now 10.

Thanks for answering that, nature called and I had to nip off!

Esel

If counter and counter1 are array indices (and so should start at zero), should you not be testing them against (number.length-1)?

Esel

Educate me here lads - were my suggestions/comments wide of the mark?

awec

Esel wrote: »

Educate me here lads - were my suggestions/comments wide of the mark?

Yup. Basically the error here is that the OP tried to access an index in the array that doesn't exist. It's a very generic error, you'll get really good at spotting where you made the mistake over time.

The foreach statement is much better in situations like this. I'm not sure how foreach works in Java, but it's bound to have it.

The counter1 variable had already been declared 2 lines above the for statement so there was no need to redeclare it within the for statement. There's no real need for the int counter1 = 0; line, putting for(int counter1 =0; ...... would have done the same thing.

For the second one:

for(int counter1 = 0; counter1 < numbers.length; counter++)

If numbers has 10 items, that means it has indexes of 0-9. We are using the less than operator, not the less than or equals, so there's no need to do .length -1, seeing as in this case 9 will be the last time that the statement is true (as 10 is not less than 10).

Esel

Thanks for that.

A few of more questions to improve my understanding, if you don't mind.

Was the OP wrong though to 'fix' the error be "I have it working now, all I did was change counter to =1" (post 5 above)?

Why didn't line 22 give a similar out-of-bounds error though:

Line 22 for(int counter = 0 ; counter < numbers.length; counter++)

Line 37 for( counter1 = 0; counter1 < numbers.length; counter1 ++);

What is the issue with the ; in Line 37?

smokiebeverage

Esel wrote: »

Was the OP wrong though to 'fix' the error be "I have it working now, all I did was change counter to =1" (post 5 above)?

Why didn't line 22 give a similar out-of-bounds error though:

Line 22 for(int counter = 0 ; counter < numbers.length; counter++)

Line 37 for( counter1 = 0; counter1 < numbers.length; counter1 ++);

What is the issue with the ; in Line 37?

Yes all he did was stop the error but his logic was still wrong

the ; at the end of the line tells java the statement is complete so all it did was count to 10 so when it went to the next line the array index was 10 but the array index only goes from 0 - 9 so 10 is out of bounds. All the OP needed to do was remove the ; and the logic would be correct as the it would have moved on to the next line and looped through the indices 0 - 9 and then stopped.