bubble sort string array

Question

I'm trying to use a bubble sort to alphabetize an array that I've read into a program. The code compiles without error but I get an Array Index Out Of Bounds Exception on my 'if' construct when I try to run the program. I have initialized int i to 0 to account for the first index of the array so I think my error is elsewhere. I'm not asking anyone to write code for me, just maybe a point in the right direction. Thanks for any help.

public static String[] bubbleSort(String[] inL)
{
    String temp;
    int i = 0, passNum;

    for(passNum = 1; passNum <= (inL.length); i++)  // controls passes through bubble sort
    {
        if(inL[i].compareToIgnoreCase(inL[i + 1]) < 0)
        {
            temp = inL[i];
            inL[i] = inL[i + 1];
            inL[i + 1] = temp;
        }
    }

    return inL; // returns sorted array 
} // end bubbleSort method

Zong · Accepted Answer · 2013-11-19 16:25:26Z

2

You compare passNum instead of i against the length of the array. Since passNum is never modified, the loop condition is always true, and i gets incremented until it exceeds the range of the array.

Even if this particular issue is resolved, you may still run into problems with off-by-one errors with your current implementation. Consider whether you should compare i against inL.length - 1.

answered Nov 19, 2013 at 16:25

Zong

6,2585 gold badges34 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

imnotmarvin Over a year ago

I realized after reading the answers here that my problem was more than an incorrect boolean operator or variable intialization. I went through my code with a debugger and found my problems. I should have done that before coming here but I wanted to say thanks to you and the others who helped me. I will not be so quick to post for help in the future.

Ted Hopp · Accepted Answer · 2013-11-19 16:25:37Z

2

You never increment passNum so i continues incrementing forever. Also, array indexing in Java is based at 0. That means that the largest valid index is inL.length - 1. Since the body of your loop accesses inL[i+1], you should arrange your code so that i never exceeds inL.length - 2. At a minimum, you should change <= to < in the for loop termination test. (However, the logic of your comparison and incrementing escapes me; you need to fix that as well.)

answered Nov 19, 2013 at 16:25

Ted Hopp

235k48 gold badges412 silver badges533 bronze badges

Comments

Dragondraikk · Accepted Answer · 2013-11-19 16:25:52Z

0

Array.length stores the total length of an array, starting counting at 1.

The first index in an array however is 0, meaning that the last index is length-1.

adjust your check in your for-loop to fix the error

answered Nov 19, 2013 at 16:25

Dragondraikk

1,67911 silver badges21 bronze badges

Comments

ford prefect · Accepted Answer · 2013-11-19 16:26:56Z

0

Your problem is the passNum <= (inL.length) it should be passNum < (inL.length) due to 0 being the first index of an array in java

answered Nov 19, 2013 at 16:26

ford prefect

7,41611 gold badges59 silver badges85 bronze badges

Collectives™ on Stack Overflow

bubble sort string array

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related