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How to remove an element from ArrayList or, LinkedList in Java?
The ArrayList and, LinkedList classes implements the List interface of the java.util package. This interface provided two variants of the remove() method to remove particular elements as shown below −
E remove(int index)
boolean remove(Object o) −
Using one of these methods you can delete a desired element from the List or, linkedList in Java.
E remove(int index) − This method accepts an integer representing a particular position in the List object and, removes the element at the given position. If the remove operation is successful, this method returns the element that has been removed.
If the index value passed to this method is less than 0 or greater than 1, an IndexOutOfBoundsException exception is raised.
Example
import java.util.ArrayList;
public class RemoveExample {
public static void main(String[] args) {
//Instantiating an ArrayList object
ArrayList<String> arrayList = new ArrayList<String>();
arrayList.add("JavaFX");
arrayList.add("Java");
arrayList.add("WebGL");
arrayList.add("OpenCV");
System.out.println("Contents of the Array List: "+arrayList);
//Removing elements
System.out.println("Elements removed: ");
System.out.println(arrayList.remove(0));
System.out.println(arrayList.remove(2));
System.out.println(" ");
//Instantiating an LinkedList object
ArrayList<String> linkedList = new ArrayList<String>();
linkedList.add("Krishna");
linkedList.add("Satish");
linkedList.add("Mohan");
linkedList.add("Radha");
System.out.println("Contents of the linked List: "+arrayList);
//Removing elements
System.out.println("Elements removed: ");
System.out.println(linkedList.remove(0));
System.out.println(linkedList.remove(2));
}
}Output
Contents of the Array List: [JavaFx, Java, WebGL, OpenCV] Elements removed: JavaFX OpenCV Contents of the linked List: [Java, WebGL] Elements removed: Krishna Radha
boolean remove(Object o) − This method accepts an object representing an element in the List and, removes the first occurrence of the given element. This method returns a boolean value which is −
true, if the operation is successful.
false, if the operation is unsuccessful.
Example
import java.util.ArrayList;
public class RemoveExample {
public static void main(String[] args) {
//Instantiating an ArrayList object
ArrayList<String> arrayList = new ArrayList<String>();
arrayList.add("JavaFX");
arrayList.add("Java");
arrayList.add("WebGL");
arrayList.add("OpenCV");
System.out.println("Contents of the Array List: "+arrayList);
//Removing elements
System.out.println("Elements removed: ");
System.out.println(arrayList.remove("JavaFX"));
System.out.println(arrayList.remove("WebGL"));
System.out.println("Contents of the array List after removing elements: "+arrayList);
System.out.println(" ");
//Instantiating an LinkedList object
ArrayList<String> linkedList = new ArrayList<String>();
linkedList.add("Krishna");
linkedList.add("Satish");
linkedList.add("Mohan");
linkedList.add("Radha");
System.out.println("Contents of the linked List: "+linkedList);
//Removing elements
System.out.println("Elements removed: ");
System.out.println(linkedList.remove("Satish"));
System.out.println(linkedList.remove("Mohan"));
System.out.println("Contents of the linked List after removing elements: "+linkedList);
}
}Output
Contents of the Array List: [JavaFX, Java, WebGL, OpenCV] Elements removed: true true Contents of the array List after removing elements: [Java, OpenCV] Contents of the linked List: [Krishna, Satish, Mohan, Radha] Elements removed: true true Contents of the linked List after removing elements: [Krishna, Radha]
The remove() method of the Iterator object
In addition to these two method you can also remove elements of the LinkedList or ArrayList objects using the remove() of the Iterator class.
Example
import java.util.ArrayList;
import java.util.Iterator;
public class RemoveExample {
public static void main(String[] args) {
//Instantiating an ArrayList object
ArrayList<String> arrayList = new ArrayList<String>();
arrayList.add("JavaFX");
arrayList.add("Java");
arrayList.add("WebGL");
arrayList.add("OpenCV");
System.out.println("Contents of the Array List: "+arrayList);
//Retrieving the Iterator object
Iterator<String> it1 = arrayList.iterator();
it1.next();
it1.remove();
System.out.println("Contents of the array List after removing elements: ");
while(it1.hasNext()) {
System.out.println(it1.next());
}
//Instantiating an LinkedList object
ArrayList<String> linkedList = new ArrayList<String>();
linkedList.add("Krishna");
linkedList.add("Satish");
linkedList.add("Mohan");
linkedList.add("Radha");
System.out.println("Contents of the linked List: "+linkedList);
//Retrieving the Iterator object
Iterator<String> it2 = linkedList.iterator();
it2.next();
it2.remove();
System.out.println("Contents of the linked List after removing elements: ");
while(it2.hasNext()) {
System.out.println(it2.next());
}
}
}Output
Contents of the Array List: [JavaFX, Java, WebGL, OpenCV] Contents of the array List after removing elements: Java WebGL OpenCV Contents of the linked List: [Krishna, Satish, Mohan, Radha] Contents of the linked List after removing elements: Satish Mohan Radha
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