Why will this code fragment not run in Java?

Question

Stared at this for hours and am so frustrated, please help:




public class PrimeNumbers {
	
	public static void main (String[] args)

		{
		
int endNum = 11;
		

		
    	boolean sieveArray[] = new boolean[endNum+1];
    	
    	for (int i = 2; i < sieveArray.length; i++)
    	{
    		sieveArray[i] = true;
    	}
    	
    	for (int i = 2; i < sieveArray.length; i++)
    		{
    			if (sieveArray[i] == true)
    			cancelMultiples(i, sieveArray);
			}
    	
    	System.out.print(sieveArray[1]);
    	
		}
	
	
    	
    	
    	
    	
public static void cancelMultiples(int prime, boolean[] sieveArray) {
        	
        	for (int i = (2*prime); i <= sieveArray.length; i += prime)
        	{
        		if (i % prime == 0)
        			sieveArray[i] = false;		
        	}
    	  	
		}
    	
    	
    	
    }

? · Accepted Answer

You have given true value to only elements 2 to 11
what about 0 and 1
so when in the last print statement you try to print element 1 it gives error

Person · Answer

It would help to know what error you're getting and where, but it looks like you're not even instantiating the first two boolean values in your array, yet you're trying to print out value 1. Java no like that. 

Also, in your cancelMultiples class, you're running i to <= array length. Don't do that. You could go out of bounds.

Trending News

Why will this code fragment not run in Java?

2 Answers