In this article, we will add one HashSet contents to another HashSet using addAll method of Collection interface
1. Adding one HashSet to another HashSet :
- This method is used to add one HashSet contents to another HashSet contents
- Returns true, if this set changed as a result of the call
Method signature:
boolean addAll(Collection c);
AddOneHashSetToAnotherHashSet.java
package in.bench.resources.java.collections;
import java.util.HashSet;
public class AddOneHashSetToAnotherHashSet {
public static void main(String[] args) {
// 1: creating HashSet object of type String
HashSet<String> hset1 = new HashSet<String>();
// adding elements to HashSet object
hset1.add("Sundar Pichai");
hset1.add("Satya Nadella");
hset1.add("Shiv Nadar");
hset1.add("Shantanu Narayen");
// Iterating using enhanced for-loop
System.out.println("Iterating original HashSet-1\n");
for(String str : hset1) {
System.out.println(str);
}
// 2: creating HashSet object of type String
HashSet<String> hset2 = new HashSet<String>();
// adding elements to HashSet object
hset2.add("Narayan Murthy");
hset2.add("Nandan Nilekeni");
hset2.add("Shibulhset SD");
boolean boolAddAll = hset1.addAll(hset2);
System.out.println("\n\nWhether invoking HashSet-1 "
+ "changed : " + boolAddAll);
// Iterating using enhanced for-loop
System.out.println("\n\nIterating after addAll operation\n");
for(String str : hset1) {
System.out.println(str);
}
}
}
Output:
Iterating original HashSet-1
Shantanu Narayen
Shiv Nadar
Sundar Pichai
Satya Nadella
Whether invoking HashSet-1 changed : true
Iterating after addAll operation
Shantanu Narayen
Shiv Nadar
Sundar Pichai
Nandan Nilekeni
Shibulhset SD
Satya Nadella
Narayan Murthy
From above example, HashSet
- doesn’t allow duplicate elements
- maximum of one null object is allowed
- while iterating, retrieve elements in random-order
Related Articles:
- How to get size or length of HashSet
- How to delete a element and delete all elements of HashSet
- retainAll() method explanation with HashSet
- How to check whether particular element is present in HashSet
- Comparing two HashSet objects using containsAll() method
- Adding one HashSet to another HashSet using addAll() method
- Various ways to iterate through HashSet
- How to reverse LinkedHashSet contents
- Sorting HashSet contents in ascending and descending order
- How to Sort HashSet in Java – 2 ways
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/tutorial/collections/interfaces/set.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Set.html
- https://docs.oracle.com/javase/7/docs/api/java/util/class-use/HashSet.html
- https://docs.oracle.com/javase/7/docs/api/java/util/HashSet.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
Happy Coding !!
Happy Learning !!
