Java Singly linked list implementation

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Singly linked list: Items can navigate in forward direction only.

Linked list operations

    Insertion: Adds an element at the beginning of the list.
    Deletion: Deletes an element at the beginning of the list.
    Display: Displays the complete list.
    Search: Searches an element using the given key.
    Delete: Deletes an element using the given key.

Linked list examples

package com.w3schools;
 
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;
        }
    }
  }
 
   public class Test<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: "+element);
        if(head == null){
            head = nd;
            tail = nd;
        } else {
            tail.setNextRef(nd);
            tail = nd;
        }
    }
 
    public void addAfter(T element, T after){
 
        Node<T> tmp = head;
        Node<T> refNode = null;
        System.out.println("Traversing nodes");
        while(true){
            if(tmp == null){
                break;
            }
            if(tmp.compareTo(after) == 0){
                refNode = tmp;
                break;
            }
            tmp = tmp.getNextRef();
        }
        if(refNode != null){
            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("Element not found.");
        }
    }
 
    public void deleteFront(){         
        if(head == null){
            System.out.println("Underflow state");
        }
        Node<T> tmp = head;
        head = tmp.getNextRef();
        if(head == null){
            tail = null;
        }
        System.out.println("Deleted element: "+tmp.getValue());
    }
 
    public void deleteAfter(T after){
 
        Node<T> tmp = head;
        Node<T> refNode = null;
        System.out.println("Traversing nodes.");
        while(true){
            if(tmp == null){
                break;
            }
            if(tmp.compareTo(after) == 0){
                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 element: "+tmp.getValue());
        } else {
            System.out.println("Element not found.");
        }
    }
 
    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 args[]){
		try {
			Test<Integer> linkedlist = new Test<Integer>();
			linkedlist.add(13);
			linkedlist.add(23);
			linkedlist.add(4);
			linkedlist.addAfter(6, 13);
			linkedlist.deleteFront();
			linkedlist.deleteAfter(23);
			System.out.println("Traversing all nodes.");
			linkedlist.traverse();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

Linked list examples

Adding element: 13
Adding element: 23
Adding element: 4
Traversing nodes
Deleted element: 13
Traversing nodes.
Deleted element: 4
Traversing all nodes.
6
23