why it throws index out of bounds exception??
- by Johanna
Hi
I want to use merge sort for sorting my doubly linked list.I have created 3 classes(Node,DoublyLinkedList,MergeSort) but it will throw this exception for these lines:
1.in the getNodes method of DoublyLinkedList---> throw new IndexOutOfBoundsException();
2.in the add method of DoublyLinkedList-----> Node cursor = getNodes(index);
3.in the sort method of MergeSort class------> listTwo.add(x,localDoublyLinkedList.getValue(x));
4.in the main method of DoublyLinkedList----->merge.sort();
this is my Merge class:(I put the whole code for this class for beter understanding)
public class MergeSort {
private DoublyLinkedList localDoublyLinkedList;
public MergeSort(DoublyLinkedList list) {
localDoublyLinkedList = list;
}
public void sort() {
if (localDoublyLinkedList.size() <= 1) {
return;
}
DoublyLinkedList listOne = new DoublyLinkedList();
DoublyLinkedList listTwo = new DoublyLinkedList();
for (int x = 0; x < (localDoublyLinkedList.size() / 2); x++) {
listOne.add(x, localDoublyLinkedList.getValue(x));
}
for (int x = (localDoublyLinkedList.size() / 2) + 1; x < localDoublyLinkedList.size(); x++) {
listTwo.add(x, localDoublyLinkedList.getValue(x));
}
//Split the DoublyLinkedList again
MergeSort sort1 = new MergeSort(listOne);
MergeSort sort2 = new MergeSort(listTwo);
sort1.sort();
sort2.sort();
merge(listOne, listTwo);
}
public void merge(DoublyLinkedList a, DoublyLinkedList b) {
int x = 0;
int y = 0;
int z = 0;
while (x < a.size() && y < b.size()) {
if (a.getValue(x) < b.getValue(y)) {
localDoublyLinkedList.add(z, a.getValue(x));
x++;
} else {
localDoublyLinkedList.add(z, b.getValue(y));
y++;
}
z++;
}
//copy remaining elements to the tail of a[];
for (int i = x; i < a.size(); i++) {
localDoublyLinkedList.add(z, a.getValue(i));
z++;
}
for (int i = y; i < b.size(); i++) {
localDoublyLinkedList.add(z, b.getValue(i));
z++;
}
}
}
and just a part of my DoublyLinkedList:
private Node getNodes(int index) throws IndexOutOfBoundsException {
if (index < 0 || index > length) {
throw new IndexOutOfBoundsException();
} else {
Node cursor = head;
for (int i = 0; i < index; i++) {
cursor = cursor.getNext();
}
return cursor;
}
}
public void add(int index, int value) throws IndexOutOfBoundsException {
Node cursor = getNodes(index);
Node temp = new Node(value);
temp.setPrev(cursor);
temp.setNext(cursor.getNext());
cursor.getNext().setPrev(temp);
cursor.setNext(temp);
length++;
}
public static void main(String[] args) {
int i = 0;
i = getRandomNumber(10, 10000);
DoublyLinkedList list = new DoublyLinkedList();
for (int j = 0; j < i; j++) {
list.add(j, getRandomNumber(10, 10000));
MergeSort merge = new MergeSort(list);
merge.sort();
System.out.println(list.getValue(j));
}
}
PLEASE help me thanks alot.
