Help with ArrayIndexOutOfBounds Exception

Question

Hi all,
I am very new to programming in general and Java in particular. I'm working on a program from a book that is supposed to read 72 hourly readings of voltage and then print the mean voltage over that time period and any hours where the voltage varies from the mean by more than ten percent.
I have an array set up that should have 72 elements created randomly, between 12000-14000. I'm getting an ArrayIndexOutOfBounds Exception when I try to run the program. So far as I understand, this means that somewhere in the program I'm trying to reference an array index that doesn't exist. I just can't see where that is! I've tried a couple different things to see if they've worked but have had no luck.
I'm sure this is just a simple thing, but I'm feeling a little under the weather and I think my brain is pickled from looking at this code for too long. Any suggestions or ideas are gladly welcomed! I'll paste the code below to take a look at. Sorry if it's ugly or messy... I'm just figuring this stuff out still!
Thanks so much-
Heather
import java.lang.*;
import java.util.*;
class VoltageReport {
VoltageReport () throws IOException {
System.out.println("Welcome to the voltage meter program!");
//int place = 0;
int MeterReadings[] = new int [71];
int place = 0;
for (int i = 0; i <= 71; i++) {
//if (place == 72) break; thought this would do it, but it doesn't.
MeterReadings[place] = (int) (Math.random()*2000+12000);
place++;
place = 0;
int VoltageMean;
VoltageMean = 0;
for (int i = 0; i <= 71; i++) {
VoltageMean = VoltageMean + MeterReadings[place];
place++;
place = 0;
VoltageMean = VoltageMean / 72;
for (int i = 0; i <= 71; i++) {
if (MeterReadings[place] < (.9 * VoltageMean)) {
System.out.println("Hour " + place + " is more than 10% lower than the " + "mean of " + VoltageMean + " .");
else if (MeterReadings[place] > (.9 * VoltageMean)) {
System.out.println("Hour " + place + " is more than 10% higher than the " + "mean of " + VoltageMean + " .");
place++;
System.out.println("That's all the information I have. Goodbye!"); }
public static void main (String [] args) throws IOException {
new VoltageReport();
}

Answer 1

if (MeterReadings[place] < (.9 * VoltageMean))
    System.out.println("Hour " + place + " is more than 10% lower than the " + "mean of " + VoltageMean + " .");
else if (MeterReadings[place] > (.9 * VoltageMean))
    System.out.println("Hour " + place + " is more than 10% higher than the " + "mean of " + VoltageMean + " .");The problem lies in the else-if. You are checking if the voltage is over 90% of the mean. I think you want to check if it is over 110% of(10% over) the mean.
else if(MeterReadings[place] > (1.1 * VoltageMean))
....And a few other things.
Arrays
int[] temp = new int[5]; // you have indexes (indices?) 0, 1, 2, 3 & 4 is the last one
// Count them, there is 5 there.  Since we always start at 0, the last one is always 1 less than the length.
// Never do temp[temp.length], this will ALWAYS end in IndexOutOfBoundsException.
// temp[temp.length-1] is the way to get the last element.
Posting code
Since you were unusually nice, no one has cut sick at you, but in the future when you post code, put it between [ code ] and [ /code ] tags (I added spaces so the forum doesn't recognize them, but you get the idea).
Cheers,
Radish21