How to sort a Linked list
I created a linked list using nodes that prints out a list(string) of names. I'm trying to write a sort method that prints out the names in alphabetical order. If this was integers it would be easy but I have no idea how to go about doing this. Any help or tips are appreciated. -I cannot use the builtin collections.sort(). I need to make my own method.
SortMethod: (this is what I used when I was printing a list of numbers out but now its strings so I know I can't use the > operator. I just don't know how to replace it.
public void Sort( BigNode front)
{
BigNode first,second,temp;
first= front;
while(first!=null) {
second = first.next;
while(second!=null) {
if(first.dataitems < second.dataitems)
{
temp = new BigNode();
temp.dataitems =first.dataitems;
first.dataitems = second.dataitems;
second.dataitems = temp.dataitems;
}
second=second.next;
}
Heres the rest of program(I dont think its needed but just in case)
import java.util.*;
public class BigNode {
public String dataitems;
public BigNode next;
BigNode front ;
BigNode current;
String a = "1", b = "2", c = "3", d = "4";
String[] listlength;
public void initList(){
front = null;
}
public BigNode makeNode(String number){
BigNode newNode;
newNode = new BigNode();
newNode.dataitems = number;
newNode.next = null;
return newNode;
}
public boolean isListEmpty(BigNode front){
boolean balance;
if (front == null){
balance = true;
}
else {
balance = false;
}
return balance;
}
public BigNode findTail(BigNode front) {
BigNode current;
current = front;
while(current.next != null){
//System.out.print(current.dataitems);
current = current.next;
} //System.out.println(current.dataitems);
return current;
}
public void addNode(BigNode front ,String name){
BigNode tail;
if(isListEmpty(front)){
this.front = makeNode(name);
}
else {
tail = findTail(front);
tail.next = makeNode(name);
}
}
public void addAfter(BigNode n, String dataItem2) { // n might need to be front
BigNode temp, newNode;
temp = n.next;
newNode = makeNode(dataItem2);
n.next = newNode;
newNode.next = temp;
}
public void findNode(BigNode front, String value) {
boolean found , searching;
BigNode curr;
curr = front;
found = false;
searching = true;
while ((!found) && (searching)) {
if (curr == null) {
searching = false;
}
else if (curr.dataitems == value) { // Not sure if dataitems should be there (.data in notes)
found = true;
}
else {
curr = curr.next;
}
}
System.out.println(curr.dataitems);
}
public void deleteNode(BigNode front, String value) {
BigNode curr, previous = null; boolean found;
if (!isListEmpty(front)){
curr = front;
found = false;
while ((curr.next != null) && (!found)) {
if(curr.dataitems.equals(value)) {
found = true;
}
else {
previous = curr;
curr = curr.next;
}
}
if (!found) {
if(curr.dataitems.equals(value)) {
found = true;
}
}
if (found) {
if (curr.dataitems.equals(front.dataitems)){ // front.dataitems may be wrong .dataitems
front = curr.next;
} else {
previous.nex开发者_JAVA技巧t = curr.next;
}
} else {
System.out.println("Node not found!");
//curr.next = null; // Not sure If this is needed
}
}
showList(front);
}
public void printNodes(String[] len){
listlength = len;
int j;
for (j = 0; j < len.length; j++){
addNode(front, len[j]);
} showList(front);
}
public void showList(BigNode front){
current = front;
while ( current.next != null){
System.out.print(current.dataitems + ", ");
current = current.next;
}
System.out.println(current.dataitems);
MenuOptions();
}
public void MenuOptions() {
Scanner in = new Scanner(System.in);
System.out.println("Choose an Option Below:");
System.out.println(a + "(Display Length of List)" + ", " + b + "(Delete a person)" + ", " + c + ("(Exit)"));
String pick = in.nextLine();
if (pick.equals(b)) {
System.out.println("Who would you like to delete?");
String delete = in.nextLine();
deleteNode(front, delete);
}
if (pick.equals(a)) {
System.out.println("Length of List = " + listlength.length);
MenuOptions();
}
if (pick.equals(c)) {
}
}
public static void main(String[] args) {
String[] names = {"Billy Joe", "Sally Mae", "Joe Blow", "Tasha Blue", "Malcom Floyd"}; // Trying to print theses names..Possibly in alphabetical order
BigNode x = new BigNode();
x.printNodes(names);
}
}
first.dataitems.compareTo(second.dataitems)<0
or if you have a comparator
comp.compare(first.dataitems, second.dataitems)<0
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