Array Index Out of Bounds Exception (Java)

Question

Here is my code:

public class countChar {

    public static void main(String[] args) {
        int i;
        String userInput = new String();

        userInput = Input.getString("Please enter a sentence");

        int[] total = totalChars(userInput.toLowerCase());

        for (i = 0; i < total.length; i++);
        {
            if (total[i] != 0) {
                System.out.println("Letter" + (char) ('a' + i) + " count =" + total[i]);
            }
        }
    }

    public static int[] totalChars(String userInput) {
        int[] total = new int[26];
        int i;
        for (i = 0; i < userInput.length(); i++) {
            if (Character.isLetter(userInput.charAt(i))) {
                total[userInput.charAt(i) - 'a']++;
            }
        }
        return total;
    }
}

The program's purpose is to ask the user for a string, and then count the number of times each character is used in the string.

When I go to compile the program, it works fine. When I run the program, I am able to enter a string in the popup box, but after I submit the string and press OK, I get an error, saying

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 26
at countChar.main(countChar.java:14)

I'm not completely sure what the problem is or how to fix it.

I think the for loop should enclose the if statement and the ; at the end is wrong. — Philip Whitehouse
– Philip Whitehouse, Commented Aug 31, 2013 at 15:51
Could you please indicate which line is line 14? (Use // <-- ArrayIndexOutOfBoundsException here) — Stewart
– Stewart, Commented Aug 31, 2013 at 15:52

Philip Whitehouse · Accepted Answer · 2013-08-31 15:54:02Z

18

for ( i = 0; i < total.length; i++ );
                                    ^-- remove the semi-colon here

With this semi-colon, the loop loops until i == total.length, doing nothing, and then what you thought was the body of the loop is executed.

edited Aug 31, 2013 at 15:54

Philip Whitehouse

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answered Aug 31, 2013 at 15:52

JB Nizet

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3 Comments

Stewart Over a year ago

I feel a different formatting of the { (ie on the end of the for line) could have made this obvious.

Boxasauras Over a year ago

I updated the code, and I now get this error:

countChar.java:18: error: illegal start of expression         public static int[]totalChars( String userInput )         ^

That error occurs for all of the other words on the second method declaration line.

ajb Over a year ago

for (i = 0; !compiler.someoneFixesTheCompilerToWarnAboutThisError(); i++) StackOverflow.answerQuestionBySomeoneToMakeThisSameErrorAgain();

What is the current value of i? I suspect it's in the thousands by now ...

Sotirios Delimanolis · Accepted Answer · 2013-08-31 15:54:13Z

9

for ( i = 0; i < total.length; i++ ); // remove this
{
    if (total[i]!=0)
        System.out.println( "Letter" + (char)( 'a' + i) + " count =" + total[i]);
}

The for loop loops until i=26 (where 26 is total.length) and then your if is executed, going over the bounds of the array. Remove the ; at the end of the for loop.

edited Aug 31, 2013 at 15:54

answered Aug 31, 2013 at 15:52

Sotirios Delimanolis

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Comments

AyAz · Accepted Answer · 2017-01-14 09:22:26Z

This is Very Good Example of minus Length of an array in java, i am giving here both examples

 public static int linearSearchArray(){

   int[] arrayOFInt = {1,7,5,55,89,1,214,78,2,0,8,2,3,4,7};
   int key = 7;
   int i = 0;
   int count = 0;
   for ( i = 0; i< arrayOFInt.length; i++){
        if ( arrayOFInt[i]  == key ){
         System.out.println("Key Found in arrayOFInt = " + arrayOFInt[i] );
         count ++;
        }
   }

   System.out.println("this Element found the ("+ count +") number of Times");
return i;  
}

this above i < arrayOFInt.length; not need to minus one by length of array; but if you i <= arrayOFInt.length -1; is necessary other wise arrayOutOfIndexException Occur, hope this will help you.

avojak · Accepted Answer · 2017-07-14 16:01:08Z

-2

import java.io.*;
import java.util.Scanner;
class ar1 {
    public static void main(String[] args) {
        //Scanner sc=new Scanner(System.in);
        int[] a={10,20,30,40,12,32};
        int bi=0,sm=0;
        //bi=sc.nextInt();
        //sm=sc.nextInt();
        for(int i=0;i<=a.length-1;i++) {
            if(a[i]>a[i+1]) 
                bi=a[i];

            if(a[i]<a[i+1])
                sm=a[i];
        }
        System.out.println("big"+bi+"small"+sm);
    }
}

edited Jul 14, 2017 at 16:01

avojak

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answered Jul 14, 2017 at 15:12

vishnu

1

1 Comment

avojak Over a year ago

Instead of simply posting a block of code, please explain your answer

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