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Introduction to Java LinkedList
Overview:
The Java LinkedList class is a part of the Java Collections Framework and implements the List, Queue, and Deque interfaces. It is used for storing elements in a linked list structure, allowing for efficient insertion and removal operations.
Key Features:
LinkedList allows null elements, maintains insertion order, and is not synchronized. It provides constant-time performance for add and remove operations.
Creating a LinkedList
Example:
Let's create a LinkedList of strings and add some elements to it.
import java.util.LinkedList;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
System.out.println(list);
}
}
Console Output:
[Apple, Banana, Cherry]
Accessing Elements
Example:
Access elements using the get() method.
import java.util.LinkedList;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
System.out.println("First element: " + list.get(0));
}
}
Console Output:
First element: Apple
Removing Elements
Example:
Remove elements using the remove() method.
import java.util.LinkedList;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
list.remove("Banana");
System.out.println(list);
}
}
Console Output:
[Apple, Cherry]
Iterating through LinkedList
Example:
Use an iterator to traverse the elements.
import java.util.LinkedList;
import java.util.Iterator;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
Iterator iterator = list.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}
}
Console Output:
Apple
Banana
Cherry
Using LinkedList as a Queue
Example:
Implement queue operations using LinkedList.
import java.util.LinkedList;
import java.util.Queue;
class Example {
public static void main(String args[]) {
Queue queue = new LinkedList();
queue.add("Apple");
queue.add("Banana");
queue.add("Cherry");
System.out.println("Queue: " + queue);
System.out.println("Removed: " + queue.remove());
System.out.println("Queue after removal: " + queue);
}
}
Console Output:
Queue: [Apple, Banana, Cherry]
Removed: Apple
Queue after removal: [Banana, Cherry]
Using LinkedList as a Deque
Example:
Perform deque operations like adding and removing elements from both ends.
import java.util.LinkedList;
import java.util.Deque;
class Example {
public static void main(String args[]) {
Deque deque = new LinkedList();
deque.addFirst("Apple");
deque.addLast("Banana");
deque.addFirst("Cherry");
System.out.println("Deque: " + deque);
deque.removeFirst();
System.out.println("Deque after removal: " + deque);
}
}
Console Output:
Deque: [Cherry, Apple, Banana]
Deque after removal: [Apple, Banana]
Checking LinkedList Size
Example:
Use the size() method to determine the number of elements in the LinkedList.
import java.util.LinkedList;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
System.out.println("Size of the LinkedList: " + list.size());
}
}
Console Output:
Size of the LinkedList: 3
Clearing a LinkedList
Example:
Use the clear() method to remove all elements from the LinkedList.
import java.util.LinkedList;
class Example {
public static void main(String args[]) {
LinkedList list = new LinkedList();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
list.clear();
System.out.println("LinkedList after clear operation: " + list);
}
}
Console Output:
LinkedList after clear operation: []
