Tutorial Playlist
191 Lessons1. Introduction to Java
2. What is Java?
3. History of Java
4. Java Tutorial for Beginners
5. How Do Java Programs Work?
6. JDK in Java
7. C++ Vs Java
8. Java vs. Python
9. Java vs. JavaScript
10. From Java Source Code to Executable
11. How to Install Java in Linux
12. How to Install Java in Windows 10
13. Java Hello World Program
14. Structure of Java Program and Java Syntax
15. Operators in Java
16. Java If-else
17. Switch Case In Java
18. Loops in Java
19. Infinite loop in Java
20. For Loop in Java
21. For Each Loop in Java
22. Constructor in Java
23. Constructor Overloading in Java
24. Copy Constructor in Java
25. Default Constructor in Java
26. Parameterized Constructors in Java
27. Constructor Chaining In Java
28. Finalize Method in Java
29. Static Method in Java
30. Equals Method in Java
31. Abstract Method in Java
32. toString() Method in Java
33. Difference between equals method in Java
34. Inheritance in Java
35. Multiple Inheritance in Java
36. Hierarchical Inheritance in Java
37. Java Classes and Objects
38. Scanner Class in java
39. All classes in java are inherited from which class
40. What is Nested Class in Java
41. POJO Class in Java
42. Anonymous Class in Java
43. Final Class in Java
44. Object Class in Java
45. Packages in Java
46. Access Modifiers in Java
47. Static Keyword In Java
48. Final Keyword in Java
49. Checked and Unchecked Exceptions in Java
50. User Defined Exception in Java
51. Error vs. Exception in Java
52. Java Collection
53. Collections in Java
54. Garbage Collection in Java
55. Generics In Java
56. Java Interfaces
57. Functional Interface in Java
58. Marker Interface in Java
59. Streams in Java
60. Byte stream in java
61. File Handling in Java
62. Thread in Java
63. Thread Lifecycle In Java
64. Daemon Thread in Java
65. Thread Priority in Java
66. Deadlock in Java
67. String Pool in Java
68. Java Database Connectivity(JDBC)
69. Design Patterns in Java
70. Functional Programming in Java
71. OOP vs Functional vs Procedural
72. Heap Memory and Stack Memory in Java
73. Applet in Java
74. Java Swing
75. Java Frameworks
76. Hibernate Framework
77. JUnit Testing
78. How to Install Eclipse IDE for Java?
79. Command line arguments in Java
80. Jar file in Java
81. Java Clean Code
82. OOPs Concepts in Java
83. Java OOPs Concepts
84. Overloading vs Overriding in Java
85. Java 8 features
86. String in Java
87. String to int in Java
88. Why String Is Immutable in Java?
89. Primitive Data Types in Java
90. Non-Primitive Data Types in Java
91. This and Super Keyword in Java
92. HashMap in Java
93. Comparable And Comparator in Java
94. Type Casting in Java
95. Arrays Sort in Java with Examples
96. Variable Hiding and Variable Shadowing in Java
97. Enum in Java
98. Substring in Java
99. Pattern Programs in Java
100. Hashcode in Java
101. What is ByteCode in Java?
102. How To Take Input From User in Java
103. GCD of Two Numbers in Java
104. Linked List in Java
105. Arithmetic Operators in Java
106. Conditional Operators in Java
107. Stack and Queue in Java
108. Array Length in Java
109. Number Pattern Program in Java
110. Split in java
111. Map In Java
112. Difference Between Throw and Throws in Java
113. Difference Between Data Hiding and Abstraction
114. HashSet in Java
115. String Length in Java
116. Factorial Using Recursion in Java
117. DateFormat in Java
118. StringBuilder Class in java
119. Instance variables in Java
120. Java List Size
121. Java APIs
122. Reverse an Array in Java
123. StringBuffer and StringBuilder Difference in Java
124. Java Program to Add Two Numbers
125. String to Array in Java
126. Regular Expressions in Java
127. Identifiers in Java
128. Data Structures in Java
129. Set in Java
130. Pass By Value and Call By Reference in Java
131. Try Catch in Java
132. Bubble Sort in Java
133. Caesar Cipher Program in Java
134. Queue in Java
135. Object Creation in Java
136. Multidimensional Array in Java
137. How to Read a File in Java
138. String Comparison in Java
139. Volatile Keyword in Java
140. Control Statements in Java
141. Jagged Array in Java
142. Two-Dimensional Array in Java
143. Java String Format
144. Replace in Java
145. charAt() in Java
146. CompareTo in Java
147. Matrix Multiplication in Java
148. Static Variable in Java
149. Event Handling in Java
150. parseInt in Java
151. Java ArrayList forEach
152. Abstraction in Java
153. String Input in Java
154. Logical Operators in Java
155. instanceof in Java
156. Math Floor in Java
157. Selection Sort Java
158. int to char in Java
159. Stringtokenizer in java
160. Implementing and Manipulating Abs in Java
161. Char array to string in java
162. Convert Double To String In Java
163. Deque in Java
164. Converting a List to an Array in Java
165. The Max function in java
166. Removing whitespace from string in java
167. String arrays in Java
168. Strings in Java Vs Strings in Cpp
169. Sum of digits of a number in Java
170. Art of Graphical User Interfaces
171. Trim in Java
172. RxJava
173. Recursion in Java
174. HashSet Java
Now Reading
175. Difference Between Java and Python
176. Square Root in Java
177. Reverse A String in Java
178. Even Odd Program in Java
179. Fibonacci Series in Java
180. Prime Number Program in Java
181. Java Program to Print Prime Numbers in a Given Range
182. Java Leap Year Program
183. Swapping of Two Numbers in Java
184. LCM of Two Numbers in Java
185. Math.sqrt() Function in Java
186. Area of Triangle in Java
187. Sort a String In Java
188. Factorial Program in Java
189. Javafx
190. Lambda expression in java
191. Setup Java Home and IDE on macOS
Welcome to this tutorial on HashSet in Java! If you're a programming enthusiast looking to explore an essential data structure for collection management, you're in the right place. HashSet Java allows you to manage collections of elements efficiently and is a convenient and efficient paradigm for storing elements while maintaining uniqueness.
Its foundation lies in a robust data structure known as a hash table. HashSet orchestrates seamless organization and access within the collection by assigning a distinct hash code to each element. This intelligent approach empowers the data structure to perform basic operations such as addition, removal, and retrieval with constant-time efficiency, as you will understand with some HashSet Java examples.
The beauty of HashSet Java 8 lies in its ability to simplify your programming journey. With HashSet methods in Java, you can effortlessly append new elements, verify the presence of an element, or selectively eliminate items. The burden of dealing with duplicates is entirely alleviated, leaving you with a streamlined approach to managing collections of any HashSet size in Java.
This tutorial provides a comprehensive overview of HashSet Java. You will learn about a hash table's features, benefits, and implementation. You will also explore the efficient storage, fast operations, and handling of duplicate elements, enabling you to manage collections in Java effectively.
Here are the features of HashSet in Java:
Here is the declaration of HashSet:
HashSet<T> set = new HashSet<>();
In the syntax above, T represents the type of elements that the HashSet will hold. Replace T with the desired type, such as Integer, String, or a custom class.
Here are the constructors of the HashSet Class:
import java.util.HashSet;
public class upGradTutorials {
public static void main(String[] args) {
// Create a HashSet
HashSet<String> set = new HashSet<>();
// Add elements to the HashSet
set.add("Apple");
set.add("Banana");
set.add("Orange");
set.add("Mango");
set.add("Grapes");
// Print the HashSet
System.out.println("HashSet: " + set);
// Check if an element exists in the HashSet
boolean containsBanana = set.contains("Banana");
System.out.println("Contains Banana? " + containsBanana);
// Remove an element from the HashSet
boolean removedOrange = set.remove("Orange");
System.out.println("Removed Orange? " + removedOrange);
// Print the size of the HashSet
System.out.println("Size of HashSet: " + set.size());
// Iterate over the elements of the HashSet
System.out.println("Elements of HashSet:");
for (String element : set) {
System.out.println(element);
}
// Clear the HashSet
set.clear();
System.out.println("HashSet after clear: " + set);
}
}
In this example, we create a HashSet called set to store strings. We add elements to the HashSet using the add() method, and then we print the HashSet using the println() method. We demonstrate checking if an element exists in the HashSet using the contains() method and removing an element using the remove() method. We also show how to get the size of the HashSet using the size() method.
We use a for-each loop to iterate over the elements of the HashSet. Finally, we use the clear() method to remove all elements from the HashSet.
The hierarchy of HashSet starts with the Object class, which is the root of the Java class hierarchy.
Next, HashSet extends the AbstractCollection class, which provides a partial implementation of the Collection interface. AbstractCollection implements the Iterable interface, allowing elements in the collection to be iterated.
HashSet extends the AbstractSet class, an abstract implementation of the Set interface. AbstractSet provides common set operations such as adding, removing, and checking for the presence of elements in the set.
Finally, HashSet is the concrete implementation of the Set interface. It represents an unordered collection of unique elements. HashSet uses a hash table data structure to store elements, providing constant-time performance for basic operations such as adding, removing, and searching for elements.
This is the hierarchy of HashSet in Java:
java.lang.Object
└─ java.util.AbstractCollection<E>
└─ java.util.AbstractSet<E>
└─ java.util.HashSet<E>
Here is the internal working of a HashSet:
Here are some important methods in HashSet:
import java.util.HashSet;
public class upGradTutorials {
public static void main(String[] args) {
HashSet<String> set = new HashSet<>();
set.add("apple");
set.add("banana");
set.add("orange");
System.out.println(set); // Output: [orange, apple, banana]
}
}
In this example, we create a HashSet of type String and add three elements: "apple", "banana", and "orange". The add() method is used to add elements to the HashSet.
import java.util.HashSet;
public class upGradTutorials {
public static void main(String[] args) {
HashSet<String> set = new HashSet<>();
set.add("apple");
set.add("banana");
set.add("orange");
set.remove("banana");
System.out.println(set); // Output: [orange, apple]
}
}
Here, we remove the element "banana" from the HashSet using the remove() method. After removal, the HashSet will contain "apple" and "orange" elements.
import java.util.HashSet;
public class upGradTutorials {
public static void main(String[] args) {
HashSet<String> set = new HashSet<>();
set.add("apple");
set.add("banana");
set.add("orange");
for (String item : set) {
System.out.println(item);
}
// Output:
// orange
// apple
// banana
}
}
In this example, we iterate through the HashSet using a for-each loop. Each element in the HashSet is printed using the println() method. The iteration order is not guaranteed to be the same as the insertion, as HashSet does not maintain any specific order for its elements.
List | Set |
Allows duplicate elements. | Does not allow duplicate elements. |
Elements are ordered and have an index-based position. | Elements are not ordered and do not have a specific position. |
Provides methods like get(), set(), and remove() to access and manipulate elements by their index. | Provides methods like add(), remove(), and contains() to add, remove, and check for the presence of elements. |
Implementations include ArrayList, LinkedList, etc. | Implementations include HashSet, TreeSet, etc. |
import java.util.HashSet;
import java.util.ArrayList;
import java.util.Collection;
public class upGradTutorials {
public static void main(String[] args) {
// Create a collection
Collection<String> collection = new ArrayList<>();
collection.add("apple");
collection.add("banana");
collection.add("orange");
// Create a HashSet from the collection
HashSet<String> set = new HashSet<>(collection);
System.out.println(set); // Output: [banana, orange, apple]
}
}
In this program, a HashSet is created and initialized with elements from an existing collection. The addAll() method is used to add all elements from the collection to the HashSet, effectively creating a HashSet with the same elements as the collection.
import java.util.HashSet;
public class upGradTutorials {
public static void main(String[] args) {
HashSet<String> set = new HashSet<>();
// Add elements, ignoring duplicates
set.add("apple");
set.add("banana");
set.add("orange");
set.add("apple"); // Ignored because it's a duplicate
System.out.println(set); // Output: [orange, apple, banana]
}
}
This program demonstrates how HashSet automatically handles duplicate elements. Multiple elements with the same value are added to the HashSet, but only unique values are stored. When printing the HashSet, duplicate elements are ignored, resulting in a set with distinct values.
import java.util.HashSet;
class Book {
private String title;
private String author;
public Book(String title, String author) {
this.title = title;
this.author = author;
}
@Override
public int hashCode() {
return title.hashCode() + author.hashCode();
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Book other = (Book) obj;
return title.equals(other.title) && author.equals(other.author);
}
@Override
public String toString() {
return "Book [title=" + title + ", author=" + author + "]";
}
}
public class upGradTutorials {
public static void main(String[] args) {
HashSet<Book> bookSet = new HashSet<>();
// Create book objects
Book book1 = new Book("Harry Potter", "J.K. Rowling");
Book book2 = new Book("The Great Gatsby", "F. Scott Fitzgerald");
Book book3 = new Book("Harry Potter", "J.K. Rowling"); // Duplicate book
// Add books to the set
bookSet.add(book1);
bookSet.add(book2);
bookSet.add(book3); // Ignored because it's a duplicate based on equals() and hashCode()
System.out.println(bookSet);
}
}
This program illustrates the usage of a HashSet to store Book objects. Each Book object is uniquely identified by its title and author. The hashCode() and equals() methods of the Book class are overridden to ensure proper comparison and uniqueness in the HashSet.
HashSet Java is a powerful and versatile data structure that simplifies collections management while ensuring uniqueness. HashSet automatically handles duplicates, making it a reliable choice for maintaining distinct values.
The flexibility of HashSet reflects in various scenarios, such as removing duplicates from a collection or quickly checking for membership. Its usage eliminates the need for manual duplicate checks and simplifies collection manipulation tasks. Although HashSet does not maintain a specific order of elements, its benefits of efficiency and automatic uniqueness make it a valuable tool in Java programming. If order preservation is a requirement, LinkedHashSet can be used as an alternative.
By understanding the capabilities and best practices of HashSet, you can harness its power to efficiently manage collections and enhance the performance of your Java applications.
A HashSet JavaScript collection stores unique elements and maintains no specific order. It uses a hash table to provide efficient storage and fast operations like adding, removing, and searching elements.
Yes, HashSet allows storing null values. It treats null as a valid element and handles it without issues during addition, removal, or retrieval operations.
No, HashSet is not a built-in data structure in Python. However, Python offers a data structure called a set, which provides similar functionality for storing unique elements and performing set operations like union, intersection, and difference.
PAVAN VADAPALLI
Director of Engineering
Director of Engineering @ upGrad. Motivated to leverage technology to solve problems. Seasoned leader for startups and fast moving orgs. Working …Read More
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upGrad does not grant credit; credits are granted, accepted or transferred at the sole discretion of the relevant educational institution offering the diploma or degree. We advise you to enquire further regarding the suitability of this program for your academic, professional requirements and job prospects before enr...