public class LinkedList {
    Node head;
    LinkedList(){
        head=null;
    }
    class Node{
        int data;
        Node next;

        Node(int val){
            data=val;
            next=null;
        }
    }

    public void InsertAtBeginning(int val){
        Node newNode = new Node(val);
        if(head==null){
            head=newNode;
        }
        else{
            Node temp;
            temp=head;
            newNode.next=temp;
            head=newNode;
        }
    }

    public void Display(){
        Node temp=head;
        System.out.println("");
        if(head==null) {
            System.out.println("Linkedlist is empty");
            return;
        }
        while(temp.next!=null){

           System.out.print(temp.data   "->");
           temp=temp.next;
        }
        System.out.print(temp.data);
    }

    public void InsertAtPosition(int pos,int val){
        Node newNode = new Node(3);
        Node temp=head;
        if(head==null){
            InsertAtBeginning(val);
            return;
        }
        for(int i=1;i<pos-1;i  ){
             temp=temp.next;
        }
        newNode.next=temp.next;
        temp.next=newNode;
        return;
    }

    public void InsertAtEnd(int val){
        Node newNode=new Node(val);
        if(head==null){
            InsertAtBeginning(val);
            return;
        }
        Node temp=head;
        while(temp.next!=null){
            temp=temp.next;
        }
        temp.next=newNode;

    }

    public void DeleteAtBeginning(){
        if(head==null){
            System.out.println("Can't delete from empty list");
            return;
        }
        Node temp=head;
        head=temp.next;
    }

    public void DeleteAtEnd(){
        Node temp1=head;
        Node temp2=head;

        while(temp1.next!=null){
            temp2=temp1;
            temp1=temp1.next;
        }
        temp2.next=null;
    }

    public void DeleteAtPosition(int pos){
        Node temp1=head;
        Node temp2=head;
        if(head==null){
            DeleteAtBeginning();
            return;
        }
        for(int i=1;i<pos;i  ){
            temp2=temp1;
            temp1=temp1.next;
        }
        if(temp1.next==null){
            DeleteAtEnd();
            return;
        }
        temp2.next=temp1.next;
    }
    public int length(){
        Node temp=head;
        int i=0;
        while(temp.next!=null){
            i  ;
        }
        //System.out.println("Length:"   i);
        return i;
    }
    public int get(int pos){
        Node temp=head;
        for(int i=1;i<=pos;i  ){
            temp=temp.next;
        }
        return temp.data;
        //System.out.println("Value at the position"   pos   "is"   temp.data);
    }

    public void update(int pos,int val){
        Node temp=head;
        for(int i=1;i<pos;i  ){
            temp=temp.next;
        }
        temp.data=val;
    }
    
    public int search(int val){
        Node temp=head;
        int i=0;
        while(temp.next!=null){
            if(temp.data==val){
                return i;
                //System.out.println("The value"   val   "is found at index"   i);
            }
            i  ;
        }
        if(temp.data==val){
            return i;
            //System.out.println("The value"   val   "is found at index"   i);
        }
        
        return -1;
    }

    public boolean contains(int val){
        Node temp=head;
        while(temp.next!=null){
            if(temp.data==val){
                return true;
                //System.out.println("True");
            }
        }
        if(temp.data==val){
            //System.out.println("True");
            return true;
        }
        else{
           // System.out.println("False");
           return false;
        }

    }

    public static void main(String[] args){

        LinkedList list = new LinkedList();
        list.Display();
        list.InsertAtEnd(9);
        list.Display();
        list.InsertAtBeginning(5);
        list.Display();
        list.InsertAtBeginning(8);
        list.InsertAtBeginning(55);
        list.InsertAtBeginning(34);
        list.Display();
        list.InsertAtPosition(2,3);
        list.Display();
        list.InsertAtEnd(9);
        list.Display();
        list.update(2,33);
        list.Display();
        list.DeleteAtBeginning();
        list.Display();
        list.DeleteAtPosition(5);
        list.Display();
        list.DeleteAtEnd();
        list.Display();
        System.out.println("The element is is position:"   list.search(8));
        System.out.println("The element is in the list:"   list.contains(5));
        System.out.println("Element at position is:"   list.get(3));
        System.out.println(list.length());
    }
    
}

Here, the last four print statement is not working.

I get the output as:

**

Linkedlist is empty

9

5->9

34->55->8->5->9

34->3->55->8->5->9

34->3->55->8->5->9->9

34->33->55->8->5->9->9

33->55->8->5->9->9

33->55->8->5->9

33->55->8->5

**

So, I have been implementing singly linkedlist and tried to print the output of it. It works fine except for the last 4 print statements. It's just blank. Why is it not working?

CodePudding user response：

Look carefully into method search(). When you iterate over LinkedList you should change currentNode after increment otherwhise you will get an infinite loop.

Node temp=head;
int i=0;
while(temp.next!=null){
    if(temp.data==val){
        return i;
        //System.out.println("The value"   val   "is found at index"   i);
    }
    i  ;
    temp = temp.next;
}

CodePudding user response：

The bug is in your search method and contain method try this

public void searchNode(int data) {  
    Node current = head;  
    int i = 1;  
    boolean flag = false;  
    //Checks whether list is empty  
    if(head == null) {  
        System.out.println("List is empty");  
    }  
    else {  
        while(current != null) {  
             //Compares node to be found with each node present in the list  
            if(current.data == data) {  
                flag = true;  
                break;  
            }  
            i  ;  
            current = current.next;  
        }  
    }  
    if(flag)  
         System.out.println("Element is present in the list at the position : "   i);  
    else  
         System.out.println("Element is not present in the list");  
}  

and similarly try another method for contain();