I am needing to sort a linked list alphabetically. I have a Linked List full of passengers names and need the passengers name to be sorted alphabetically. How would one do this? Anyone have any references or videos?
This question is related to
java
linked-list
I wouldn't. I would use an ArrayList or a sorted collection with a Comparator. Sorting a LinkedList is about the most inefficient procedure I can think of.
Here is the example to sort implemented linked list in java without using any standard java libraries.
package SelFrDemo;
class NodeeSort {
Object value;
NodeeSort next;
NodeeSort(Object val) {
value = val;
next = null;
}
public Object getValue() {
return value;
}
public void setValue(Object value) {
this.value = value;
}
public NodeeSort getNext() {
return next;
}
public void setNext(NodeeSort next) {
this.next = next;
}
}
public class SortLinkList {
NodeeSort head;
int size = 0;
NodeeSort add(Object val) {
// TODO Auto-generated method stub
if (head == null) {
NodeeSort nodee = new NodeeSort(val);
head = nodee;
size++;
return head;
}
NodeeSort temp = head;
while (temp.next != null) {
temp = temp.next;
}
NodeeSort newNode = new NodeeSort(val);
temp.setNext(newNode);
newNode.setNext(null);
size++;
return head;
}
NodeeSort sort(NodeeSort nodeSort) {
for (int i = size - 1; i >= 1; i--) {
NodeeSort finalval = nodeSort;
NodeeSort tempNode = nodeSort;
for (int j = 0; j < i; j++) {
int val1 = (int) nodeSort.value;
NodeeSort nextnode = nodeSort.next;
int val2 = (int) nextnode.value;
if (val1 > val2) {
if (nodeSort.next.next != null) {
NodeeSort CurrentNext = nodeSort.next.next;
nextnode.next = nodeSort;
nextnode.next.next = CurrentNext;
if (j == 0) {
finalval = nextnode;
} else
nodeSort = nextnode;
for (int l = 1; l < j; l++) {
tempNode = tempNode.next;
}
if (j != 0) {
tempNode.next = nextnode;
nodeSort = tempNode;
}
} else if (nodeSort.next.next == null) {
nextnode.next = nodeSort;
nextnode.next.next = null;
for (int l = 1; l < j; l++) {
tempNode = tempNode.next;
}
tempNode.next = nextnode;
nextnode = tempNode;
nodeSort = tempNode;
}
} else
nodeSort = tempNode;
nodeSort = finalval;
tempNode = nodeSort;
for (int k = 0; k <= j && j < i - 1; k++) {
nodeSort = nodeSort.next;
}
}
}
return nodeSort;
}
public static void main(String[] args) {
SortLinkList objsort = new SortLinkList();
NodeeSort nl1 = objsort.add(9);
NodeeSort nl2 = objsort.add(71);
NodeeSort nl3 = objsort.add(6);
NodeeSort nl4 = objsort.add(81);
NodeeSort nl5 = objsort.add(2);
NodeeSort NodeSort = nl5;
NodeeSort finalsort = objsort.sort(NodeSort);
while (finalsort != null) {
System.out.println(finalsort.getValue());
finalsort = finalsort.getNext();
}
}
}
In java8 you no longer need to use Collections.sort method as LinkedList inherits the method sort from java.util.List, so adapting Fido's answer to Java8:
LinkedList<String>list = new LinkedList<String>();
list.add("abc");
list.add("Bcd");
list.add("aAb");
list.sort( new Comparator<String>(){
@Override
public int compare(String o1,String o2){
return Collator.getInstance().compare(o1,o2);
}
});
References:
http://docs.oracle.com/javase/8/docs/api/java/util/LinkedList.html
http://docs.oracle.com/javase/7/docs/api/java/util/List.html
Node mergeSort(Node head) {
if(head == null || head.next == null) {
return head;
}
Node middle = middleElement(head);
Node nextofMiddle = middle.next;
middle.next = null;
Node left = mergeSort(head);
Node right = mergeSort(nextofMiddle);
Node sortdList = merge(left, right);
return sortdList;
}
Node merge(Node left, Node right) {
if(left == null) {
return right;
}
if(right == null) {
return left;
}
Node temp = null;
if(left.data < right.data) {
temp = left;
temp.next = merge(left.next, right);
} else {
temp = right;
temp.next = merge(left, right.next);
}
return temp;
}
Node middleElement(Node head) {
Node slow = head;
Node fast = head;
while (fast != null && fast.next != null && fast.next.next != null) {
fast = fast.next.next;
slow = slow.next;
}
return slow;
}
In order to sort Strings alphabetically you will need to use a Collator, like:
LinkedList<String> list = new LinkedList<String>();
list.add("abc");
list.add("Bcd");
list.add("aAb");
Collections.sort(list, new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
return Collator.getInstance().compare(o1, o2);
}
});
Because if you just call Collections.sort(list) you will have trouble with strings that contain uppercase characters.
For instance in the code I pasted, after the sorting the list will be: [aAb, abc, Bcd] but if you just call Collections.sort(list); you will get: [Bcd, aAb, abc]
Note: When using a Collator you can specify the locale Collator.getInstance(Locale.ENGLISH) this is usually pretty handy.
You can do it by Java 8 lambda expression :
LinkedList<String> list=new LinkedList<String>();
list.add("bgh");
list.add("asd");
list.add("new");
//lambda expression
list.sort((a,b)->a.compareTo(b));
LinkedList<String>list = new LinkedList<String>();
list.add("abc");
list.add("Bcd");
list.add("aAb");
list.sort(String::compareToIgnoreCase);
Another option would be using lambda expressions:
list.sort((o1, o2) -> o1.compareToIgnoreCase(o2));
If you'd like to know how to sort a linked list without using standard Java libraries, I'd suggest looking at different algorithms yourself. Examples here show how to implement an insertion sort, another StackOverflow post shows a merge sort, and ehow even gives some examples on how to create a custom compare function in case you want to further customize your sort.
Source: Stackoverflow.com