问题
inside of the arrayAverage method, avg has the right value (I tested it by puting println (avg) inside of the method. When i call the method from my main method and then print avg, netbeans tells me that the variable may not have been initialized. I must be doing something wrong, but I cannot figure out what.
/*****************************************************************************\
* randomIntCount |
* program generates a list of random numbers from 1-10, calculates |
* the frequency of each number (1-10), calculates the mean, and |
* outputs mean and frequency to a txt file | |
* created for CSci 111 |
* Last modified 10/23/2013 |
*****************************************************************************/
package randomintcount;
/**
*@author Steve Pesce
*
*/
public class RandomIntCount {
/**
* Main method generates an array of 1000 random numbers and calls other
* methods to calculate frequency, calculate average and output these to a
* text file
*/
public static void main(String[] args) {
int [] randomNumbers = new int [1000]; //1000 random numbers
int i; //loop counter
int [] count = new int [11]; //frequency of 1-10 in randomNumbers[]
double avg; /* Ʃ[ number * frequency]
calculation of mean(avg): ----------------------
arrayLength
*/
int arrayLength; //used in mean calculation
count[0] = 0;
for (i = 0; i < randomNumbers.length; i++ ) //fill randomNumbers with
{ //random numbers
randomNumbers[i] = (int) ((Math.random() * 10) + 1);
}
arrayLength = randomNumbers.length;
//------------------------
for (i = 1; i < 11; i++) //count controlled loop
{ //that uses frequencyCounter
frequencyCounter(randomNumbers, count, i); //method for each possible
} //value
//-----------------------------
for (i = 1; i < count.length; i++)
{
System.out.println (count [i]); //TEST DELETE ME!
}
System.out.println("length " + arrayLength); //TEST DELETE ME!
averageArray(count, arrayLength);
System.out.println (avg);
}
/******************************************************************************\
| frequencyCounter counts the frequency of a number in a given array |
| uses numbers[], count[], and i |
| numbers[]: the sample array of numbers |
| count []: array that holds the frequency of a value in numbers[n] |
| i: used as a counter for count [] |
| |
| returns: count |
\----------------------------------------------------------------------------**/
public static void frequencyCounter (int[] numbers, int[] count, int i )
{
int n; //for count controlled loop
for (n = 0; n <1000; n++) //for loop that checks if loop
{ // counter from method calling loop(i)
if (numbers[n] == i) //is equal to values from numbers[]
count[i]++; //and incriments count sub counter
}
}
/******************************************************************************\
| this method finds the average of an array using |
| Ʃ[ number * frequency]|
| calculation of mean(avg): ---------------------|
| arrayLength |
|method paramaters: int[] count |
| int arrayLength |
| Method returns mean as (double avg) |
|_____________________________________________________________________________*/
public static double averageArray (int[] count,int arrayLength)
{
double totalSum = 0;
double avg = 0;
int i; //for count controlled loop
for (i = 1; i < count.length; i++)//uses formula calculation of mean
{ //to find avg. CTRL+F calculation of mean
totalSum = ((count[i] * i) +totalSum);//to see formula used (document-
} //ed in main method)
avg = (totalSum/ arrayLength );
System.out.println(avg); //just a test to see if avg was initialized
return avg;
}
}
回答1:
Your averageArray method returns the average, but you forgot to assign it to avg in main. Nothing currently gives the avg variable in main a value. Change
averageArray(count, arrayLength);
to
avg = averageArray(count, arrayLength);
来源：https://stackoverflow.com/questions/19554287/variable-may-not-have-been-initialized