Can someone take a look at my Radix sort code and help me figure out how i can properly enque the new entry? Because as of right now the way i did it seems to never be able to set a second entry... It always points it as a null for some reason. I tried to set the tempNode to = new Node(newEntry) then just set the next constalty to null if its not defined but that still did not work.
class LinkedQueue<T> implements QueueInterface<T> {
private Node start;
private Node end;
public LinkedQueue() {
start = null;
end = null;
}
@Override
public void enqueue(T newEntry) {
Node tempNode = new Node(newEntry, null);
if (isEmpty()) {
start = tempNode;
} else {
end.setNext(tempNode);
end = tempNode;
}
}
@Override
public T dequeue() {
T front = null;
if (!isEmpty()) {
front = start.getData();
start = start.getNext();
if (start == null) // verification purposes
end = null;
}
return front;
}
@Override
public T getFront() {
T front = null;
if (!isEmpty())
front = start.getData();
return front;
}
@Override
public boolean isEmpty() {
return (start == null && end == null);
}
// reset the list
@Override
public void clear() {
start = null;
end = null;
}
private class Node {
private T data;
private Node next;
public Node(T data) {
this.data = data;
next = null;
}
public Node(T data, Node next) {
this.data = data;
this.next = next;
}
public T getData() {
return data;
}
public void setData(T data) {
this.data = data;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}
}
public class RadixSorting {
public static final int MAX = 10;
public static void radixSort(int[] myArray, int start, int last, int maxDigit) {
@SuppressWarnings("unchecked")
QueueInterface<Integer>[] buckets = new LinkedQueue[MAX];
System.out.println("\n");
System.out.println("Buckets size:" + buckets.length);
int bucket;
int index;
int i;
for (bucket = 0; bucket < MAX; bucket++)
buckets[bucket] = new LinkedQueue<Integer>();
int multiplier = 1;
for (i = 1; i <= maxDigit; i++, multiplier *= MAX) {
for (bucket = 0; bucket < MAX; bucket++)
buckets[bucket].clear();
for (index = start; index <= last; index++) {
int tempNum = (myArray[index] % (multiplier * MAX)) / multiplier;
buckets[tempNum].enqueue(myArray[index]);
}
bucket = 0;
for (index = start; index <= last; index++) {
while (buckets[bucket].isEmpty())
bucket++;
myArray[index] = buckets[bucket].dequeue();
}
}
}
public static void main(String args[]) {
int array[] = { 5, 50, 15, 45, 40, 10, 25, 30, 20, 35 };
RadixSorting.radixSort(array, 0, array.length -1, 4);
}
}
Heres my error:
Exception in thread "main" java.lang.NullPointerException
at week5.LinkedQueue.enqueue(RadixSorting.java:51)
at week5.RadixSorting.radixSort(RadixSorting.java:143)
at week5.RadixSorting.main(RadixSorting.java:157)
