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Java Program to demonstrate the use of LinkedList.

Java Code Example — Collection Programs

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Java Program to demonstrate the use of LinkedList.

Objective

Write a Java program to demonstrate LinkedList operations.

Algorithm / Approach

  1. Import java.util.*.
  2. Instantiate a LinkedList<Integer>.
  3. Use ll.add(x) to append items.
  4. Use ll.indexOf(x) to search for an item.
  5. Use ll.remove(index) to delete an item.
Test.java 
import java.util.*;
class Test {
 LinkedList<Integer> ll;
 Scanner s;
 Test() {
  ll = new LinkedList<Integer>();
  s = new Scanner(System.in);
 }
 void addElement() {
  char c = 'y';
  while(c=='y') {
   System.out.print("Enter Element: ");
   int x = s.nextInt();
   ll.add(x);
   System.out.print("Want to Add[y/n]: ");
   try {
    c=(char)System.in.read();
   }
   catch(Exception e) { }
  }
 }
 void show() {
  System.out.println(ll);
  System.out.println("Size: "+ll.size());
 }
 void find() {
  System.out.print("Element to find: ");
  int x = s.nextInt();
  int i = ll.indexOf(x);
  if(i == -1) {
   System.out.println("NOT in List");
  }
  else {
   System.out.println("Find at "+(i+1));
  }
 }
 void delete() {
   System.out.print("Element to delete: ");
  int x = s.nextInt();
  int index = ll.indexOf(x);
  if(index == -1) {
   System.out.println("NOT in List");
  }
  else {
   ll.remove(index);
   System.out.println("Now List: "+ll);
  }
 }

 public static void main(String[] a)
  throws Exception
 { 
  Test t = new Test();
  System.out.println("Add in List ");
  t.addElement();
  t.show();
  t.find();
 }
}

Expected Output

Add in List
Enter Element: 1
Want to Add[y/n]: y
Enter Element: 2
Want to Add[y/n]: y
Enter Element: 3
Want to Add[y/n]: y
Enter Element: 4
Want to Add[y/n]: y
Enter Element: 5
Want to Add[y/n]: y
Enter Element: 6
Want to Add[y/n]: y
Enter Element: 7
Want to Add[y/n]: y
Enter Element: 8
Want to Add[y/n]: y
Enter Element: 9
Want to Add[y/n]: n
[1, 2, 3, 4, 5, 6, 7, 8, 9]
Size: 9
Element to find: 12
NOT in List
Element to delete: 5
Now List: [1, 2, 3, 4, 6, 7, 8, 9]

Explanation of the Program

  • LinkedList implements both the List and Deque interfaces.
  • Internally, it uses a doubly-linked list data structure. Each element (node) stores the data as well as memory pointers to both the previous and next nodes in the chain.
  • While ArrayList is faster for retrieving data (using an index), LinkedList is much faster for inserting or deleting data in the middle of the list, because it only requires updating a few pointers rather than shifting thousands of elements in an array.

Complexity

Time Complexity O(n) - For traversing nodes during search/remove operations.
Space Complexity O(n)
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