How to implement a Linked List in Java? [duplicate]

Answer 1

//Single linked list implementation

public class Nodes {

    int data;
    Nodes next = null;

    public Nodes(int data) {
        this.data = data;
    }
}


public class Lists {

    static Nodes first = null;

    public static void insertBegin(int data) {
        Nodes temp = new Nodes(data);
        if(first == null) {
            first = temp;
        }
        else {
            temp.next = first;
            first = temp;           
        }
    }

    public static void insertEnd(int data) {
        Nodes temp = new Nodes(data);
        if(first == null) {
            first = temp;
        }
        else{
            Nodes n = first;
            while(n.next != null) {
                n = n.next;
            }
            n.next = temp;
        }
    }

    public static void insertPos(int pos, int data) {
        Nodes temp = new Nodes(data);
        if(first == null) {
            System.out.println("List empty. Cannot insert");
        }
        else {
            Nodes n = first;
            while(n.data != pos && n.next != null) {
                n = n.next;
            }
            if(n.data != pos){
                System.out.println("Position not found");
            }
            else {
                temp.next = n.next;
                n.next = temp;
            }
        }
    }

    public static void deleteBegin() {
        if(first == null) {
            System.out.println("List empty. Cannot delete");
        }
        else {
            first = first.next;
        }       
    }


    public static void deleteEnd() {
        if(first == null) {
            System.out.println("List empty. Cannot delete");
        }
        else {
            Nodes n = first;
            while(n.next.next != null) {
                n = n.next;
            }
            n.next = n.next.next;
        }
    }

    public static void deletePos(int pos) {
        if(first == null) {
            System.out.println("List empty. Cannot delete");
        }
        else {
            Nodes n = first;
            while(n.next.data != pos && n.next.next != null) {
                n = n.next;
            }
            if(n.next.data != pos) {
                System.out.println("Element not found. Deletion failed");
            }
            else{
                n.next = n.next.next;
            }
        }
    }

    public static void printAll() {
        System.out.println("Elements in link list");
        Nodes n = first;
        while(n != null) {
            System.out.print(n.data + "->");
            n = n.next;
        }
    }
}