LinkedList

• LinkedList is an implementation of a list interface where one can add any element at any index and remove any element from any index or position.
• Here, elements are doubly linked to one another which makes it easy to add or remove elements from both ends.

Various operations performed on the LinkedList:

1. Addition of elements in the LinkedList:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                         new LinkedList<>();    // Instantiation of LinkedList

    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                    // Adding Element to the LinkedList
    linkedList.add(40);
    linkedList.add(50);
    
    System.out.println(linkedList);
  }
}

Output:

[10, 20, 30, 40, 50]

2. Addition of element at particular index:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                         new LinkedList<>();    // Instantiation of LinkedList

    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                                    
    linkedList.add(40);
    linkedList.add(50);
    
    linkedList.add(2,60);      // Adding Element at particular index
    
    System.out.println(linkedList);
  }
}

Output:

[10, 20, 60, 30, 40, 50]

3. Addition of a LinkedList in another LinkedList:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList1 = 
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList1.add(10);
    linkedList1.add(20);
    linkedList1.add(30);                     // Adding Element in linkedList1
     
    LinkedList<Integer> linkedList2 = 
                        new LinkedList<>();    // Instantiation of LinkedList2
    
    linkedList2.add(40);
    linkedList2.add(50);
    linkedList2.add(60);                    // Adding Element in linkedList2
   
    
    linkedList1.addAll(linkedList2);      // Adding linkedList2 in linkedList1
    
    System.out.println(linkedList1);
  }
}

Output:

[10, 20, 30, 40, 50, 60]

4. Removing a single element from LinkedList:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                        new LinkedList<>();     // Instantiation of LinkedList
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                        // Adding Element in LinkedList
    linkedList.add(40);
    linkedList.add(50);
                                    
    linkedList.remove();            // Removing single element from LinkedList
    System.out.println(linkedList);
  }
}

Output:

[20, 30, 40, 50]

5. Removing elements from a particular index:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                        new LinkedList<>();     // Instantiation of LinkedList
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                        // Adding Element in LinkedList
    linkedList.add(40);
    linkedList.add(50);
                                    
    linkedList.remove(1);                     // Removing element from index
    System.out.println(linkedList);
  }
}

Output:

[10, 30, 40, 50]

6. Removing all elements from LinkedList:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                        // Adding Element in linkedList
    linkedList.add(40);
    linkedList.add(50);
    
    System.out.println("LinkedList before removal: "+linkedList);                              
    linkedList.clear();                             // removal of all element
    System.out.println("LinkedList after  removal: "+linkedList);
  }
}

Output:

LinkedList before removal: [10, 20, 30, 40, 50]
LinkedList after  removal: []

7. Updating element at particular index:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList =
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                       // Adding Element in linkedList
    linkedList.add(40);
    linkedList.add(50);
    
    linkedList.set(2,25);                      // Updation of element
     
    System.out.println(linkedList);
  }
}

Output:

[10, 20, 25, 40, 50]

8. Check whether the given element is present inside the list or not:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                        // Adding Element in linkedList
    linkedList.add(40);
    linkedList.add(50);
     
    System.out.println(linkedList.contains(50));
    System.out.println(linkedList.contains(0));
  }
}

Output:

true
false

9. Traversing:

Example:

import java.util.*;
public class LinkedList {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                        // Adding Element in linkedList
    linkedList.add(40);
    linkedList.add(50);
     
    // using for loop 
    System.out.println("Traversing using for loop: ");
    for(int i=0;i<linkedList.size();i++)
    {
        System.out.print(linkedList.get(i)+" ");
    }
    // using foreach loop
    System.out.println("\nTraversing using foreach loop: ");
    for(int list:linkedList)
    {
        System.out.print(list+" ");
    }
  }
}

Output:

Traversing using for loop: 
10 20 30 40 50 
Traversing using foreach loop: 
10 20 30 40 50 

10. Iteration:

Example:

import java.util.*;
import java.util.Iterator;
public class Main {

  public static void main(String args[]) {

    LinkedList<Integer> linkedList = 
                       new LinkedList<>();     // Instantiation of LinkedList1
 
    linkedList.add(10);
    linkedList.add(20);
    linkedList.add(30);                      // Adding Element in linkedList
    linkedList.add(40);
    linkedList.add(50);
     
    Iterator it = linkedList.iterator();           // Iteration
    while(it.hasNext())
   {
       System.out.println(it.next());
   }
  }
}

Output:

10
20
30
40
50