In this article, we will discuss an example of ArrayList on how to delete a particular element and later deleting all elements
1. ArrayList :
Below methods helps to delete single element or deletes all elements of an ArrayList,
- remove(Object) –> to delete a particular element by specifying object name
- clear() –> to delete all elements present in ArrayList
Note: Both above methods inherited from Collection interface
2. Delete an element & Delete all elements of an ArrayList :
Below ArrayList example depicts
- Deleting a particular element by specifying object name
- Deleting all elements or clearing ArrayList
DeleteAndDeleteAllElementsOfArrayList.java
package in.bench.resources.java.collections;
import java.util.ArrayList;
public class DeleteAndDeleteAllElementsOfArrayList {
public static void main(String[] args) {
// creating ArrayList object of type String
ArrayList<String> al = new ArrayList<String>();
// adding elements to ArrayList object
al.add("Sundar Pichai");
al.add("Satya Nadella");
al.add("Shiv Nadar");
al.add("Shantanu Narayen");
al.add("Sundar Pichai"); // duplicate object
al.add("Francisco D’Souza");
al.add(null); // null is allowed
System.out.println("Intial size of an ArrayList is : "
+ al.size());
// Iterating using for-loop
System.out.println("\nIterating "
+ "ArrayList elements using for-loop\n");
for(int index = 0; index < al.size(); index++) {
System.out.println(al.get(index));
}
// deleting particular element
al.remove("Shiv Nadar");
System.out.println("\n\nArrayList size after deleting : "
+ al.size());
// Iterating using enhanced for-loop
System.out.println("\nIterating "
+ "after deleting particular object\n");
for(String str : al) {
System.out.println(str);
}
// deleting all elements
al.clear();
System.out.println("\n\nArrayList size after clearing : "
+ al.size());
// Iterating using enhanced for-loop
System.out.println("\nIterating after clearing ArrayList\n"
+ al);
}
}
Output:
Intial size of an ArrayList is : 7
Iterating ArrayList elements using for-loop
Sundar Pichai
Satya Nadella
Shiv Nadar
Shantanu Narayen
Sundar Pichai
Francisco D’Souza
null
ArrayList size after deleting : 6
Iterating after deleting particular object
Sundar Pichai
Satya Nadella
Shantanu Narayen
Sundar Pichai
Francisco D’Souza
null
ArrayList size after clearing : 0
Iterating after clearing ArrayList
[]
From above example, ArrayList
- allows duplicate elements
- null object is allowed
- while iterating insertion-order is maintained
Q) What happens to ArrayList, when duplicate element is deleted ?
- Deletes 1st occurrence of duplicate element
- But other duplicate elements in ArrayList remain unchanged, except changing its index–position
- That’s moving upward direction by one index-position
Related Articles:
- Java – Creating ArrayList using nCopies method of Collections class
- Java – How to get size or length of an ArrayList ?
- Java – Adding element to ArrayList at specified index position
- Java – Remove element from ArrayList at specified index position
- Java – How to delete a element and delete all elements of an ArrayList ?
- Java- How to get sublist from ArrayList ?
- Java – How to check whether particular element is present in ArrayList ?
- Java – Comparing two ArrayList objects using containsAll() method
- Java – Adding one ArrayList to another ArrayList using addAll() method
- Java – Replacing ArrayList element with new value using set() method
- Java – Various ways to iterate through ArrayList
- Java – How to reverse ArrayList contents ?
- Java – Remove duplicate elements from ArrayList
- Java – How to remove duplicate elements of ArrayList maintaining insertion-order ?
References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Enumeration.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/7/docs/api/java/util/ListIterator.html
Happy Coding !!
Happy Learning !!