CODEWITHSUNDEEP
javaarrayssortingrecursionbubble-sort
randomizertech
randomizertech

Reputation: 2329

Recursive Bubble Sort in Java

I am trying to write a Recursive Bubble sort in Java and I'm getting an Index Out of Bounds Exception. What am I doing wrong and why am I getting this error? Here is my code:

public static  <T extends Comparable< ? super T>>
    void sort(T [] a){
    T tmp;
    for(int i=0;i<a.length;i++){
        if(a[i].compareTo(a[i+1])>0){
            tmp = a[i];
            a[i]=a[i+1];
            a[i+1]=tmp;
            sort(a);
        }
        System.out.println("i:"+i+" "+a[i]);

    }

Also, even tho it sorts the array and I get the error at the end, it is printing all of the steps, how do I make it print the last final sorted array? Is probably a simple answer but my brain is fried right now and can't think straight. Thanks in advance.

Upvotes: 3

Views: 4300

Answers (5)

Dulanjana Nehan
Dulanjana Nehan

Reputation: 1

The IndexOutOfBoundsException happens because your loop tries to access a[i+1] when i is at the last index (a.length - 1), which goes out of bounds.

To fix it, adjust the loop to run until i < a.length - 1, so a[i+1] is always valid:

public static <T extends Comparable<? super T>> void sort(T[] a) {
    T tmp;
    boolean swapped = false;

    for (int i = 0; i < a.length - 1; i++) {  
        if (a[i].compareTo(a[i + 1]) > 0) {
            tmp = a[i];
            a[i] = a[i + 1];
            a[i + 1] = tmp;
            swapped = true;
        }
    }

    if (swapped) {
        sort(a); 
    } else {
        // Print the final sorted array
        for (T element : a) {
            System.out.print(element + " ");
        }
        System.out.println();
    }

The error happened because the loop tried to access an index that doesn’t exist (a[i+1] when i is at a.length - 1). The fix ensures valid index access and lets the array sort correctly, printing the final sorted array only once at the end.

Upvotes: 0

Arafe Zawad Sajid
Arafe Zawad Sajid

Reputation: 92

Try this.

 public static void bubbleSort(Object[] source, int fromIndex, int endIndex){
            if(fromIndex==endIndex){
                return;
            }
            else{
                if(((Comparable) source[fromIndex]).compareTo(source [fromIndex+1])>0){
                    Object temp=source[fromIndex];
                    source[fromIndex]=source[fromIndex+1];
                    source[fromIndex+1]=temp;
                }
                bubbleSort(source,fromIndex+1,endIndex);
            }
            bubbleSort(source,fromIndex,endIndex-1);
        }

Upvotes: -1

&#211;scar L&#243;pez
&#211;scar L&#243;pez

Reputation: 236004

The loop should stop when i < a.length-1 , because in your code you access the position i+1, and when i == a.length - 1 then i+1 will be trying to access an element off the end of the array that doesn't exist - hence, out of bounds.

Upvotes: 10

Ted Hopp
Ted Hopp

Reputation: 234795

You've written your loop so that i gets as bit as a.length - 1. Then you are trying to access a[i+1], which is an out-of-bounds index when i == a.length - 1. Lower your loop's limit by 1.

Upvotes: 5

Al Kepp
Al Kepp

Reputation: 5980

The upper limit should be length-1

for(int i=0;i<a.length-1;i++)

Upvotes: 2

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