冒泡排序字符串数组

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

Answer 1

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 .

Answer 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.)

Answer 3

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

Answer 4

您的问题是passNum <= (inL.length)它应该是passNum < (inL.length)因为0是Java中数组的第一个索引