Singly linked list implementation
Singly Linked Lists are a type of data structure. It is a type of list. In a singly linked list each node in the list
stores the contents of the node and a pointer or reference to the next node in the list. It does not store any pointer or reference
to the previous node. It is called a singly linked list because each node only has a single link to another node. To store a single
linked list, you only need to store a reference or pointer to the first node in that list. The last node has a pointer to nothingness
to indicate that it is the last node.
Here is the pictorial view of singly linked list:
Here is the pictorial view of inserting an element in the middle of a singly linked list:
Here is the pictorial view of deleting an element in the middle of a singly linked list:
Below shows the java implementation of singly linked list:
package com.java2novice.ds.linkedlist;
public class SinglyLinkedListImpl<T> {
private Node<T> head;
private Node<T> tail;
public void add(T element){
Node<T> nd = new Node<T>();
nd.setValue(element);
System.out.println("Adding: "+element);
/**
* check if the list is empty
*/
if(head == null){
//since there is only one element, both head and
//tail points to the same object.
head = nd;
tail = nd;
} else {
//set current tail next link to new node
tail.setNextRef(nd);
//set tail as newly created node
tail = nd;
}
}
public void addAfter(T element, T after){
Node<T> tmp = head;
Node<T> refNode = null;
System.out.println("Traversing to all nodes..");
/**
* Traverse till given element
*/
while(true){
if(tmp == null){
break;
}
if(tmp.compareTo(after) == 0){
//found the target node, add after this node
refNode = tmp;
break;
}
tmp = tmp.getNextRef();
}
if(refNode != null){
//add element after the target node
Node<T> nd = new Node<T>();
nd.setValue(element);
nd.setNextRef(tmp.getNextRef());
if(tmp == tail){
tail = nd;
}
tmp.setNextRef(nd);
} else {
System.out.println("Unable to find the given element...");
}
}
public void deleteFront(){
if(head == null){
System.out.println("Underflow...");
}
Node<T> tmp = head;
head = tmp.getNextRef();
if(head == null){
tail = null;
}
System.out.println("Deleted: "+tmp.getValue());
}
public void deleteAfter(T after){
Node<T> tmp = head;
Node<T> refNode = null;
System.out.println("Traversing to all nodes..");
/**
* Traverse till given element
*/
while(true){
if(tmp == null){
break;
}
if(tmp.compareTo(after) == 0){
//found the target node, add after this node
refNode = tmp;
break;
}
tmp = tmp.getNextRef();
}
if(refNode != null){
tmp = refNode.getNextRef();
refNode.setNextRef(tmp.getNextRef());
if(refNode.getNextRef() == null){
tail = refNode;
}
System.out.println("Deleted: "+tmp.getValue());
} else {
System.out.println("Unable to find the given element...");
}
}
public void traverse(){
Node<T> tmp = head;
while(true){
if(tmp == null){
break;
}
System.out.println(tmp.getValue());
tmp = tmp.getNextRef();
}
}
public static void main(String a[]){
SinglyLinkedListImpl<Integer> sl = new SinglyLinkedListImpl<Integer>();
sl.add(3);
sl.add(32);
sl.add(54);
sl.add(89);
sl.addAfter(76, 54);
sl.deleteFront();
sl.deleteAfter(76);
sl.traverse();
}
}
class Node<T> implements Comparable<T> {
private T value;
private Node<T> nextRef;
public T getValue() {
return value;
}
public void setValue(T value) {
this.value = value;
}
public Node<T> getNextRef() {
return nextRef;
}
public void setNextRef(Node<T> ref) {
this.nextRef = ref;
}
@Override
public int compareTo(T arg) {
if(arg == this.value){
return 0;
} else {
return 1;
}
}
}
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