Iterating over a HashSet is essential for processing each element stored in the set. Although HashSet does not maintain any specific order, you can traverse its elements using various methods. Two common approaches for iteration are the for-each loop and the Iterator interface. Both techniques allow you to access each element in the set, but they offer different levels of control over the iteration process.

• For-Each Loop: A simple and concise way to iterate through all elements.
• Iterator: Provides explicit control, including the ability to remove elements during iteration.

1. Iterating Using a For-Each Loop

The for-each loop simplifies iteration by automatically accessing each element in the collection one by one. This method is very readable and is typically used when you do not need to modify the collection during iteration.

Syntax:

for (Type element : hashSet) {
    // Process element
}

• Explanation:
  • hashSet is the collection you want to iterate over.
  • element represents the current element in the iteration.
  • The loop automatically iterates over each element in the HashSet.

Example:

Example Explanation:

• For-Each Loop:
  • The for-each loop automatically iterates over each element in the colors HashSet.
  • Each element is printed without needing to manage an iterator manually.
• Outcome:
  • All colors in the set are displayed, though the order is not guaranteed.

2. Iterating Using an Iterator

The Iterator interface offers more control over the iteration process. It allows you to traverse the collection and also supports the removal of elements while iterating. This method is useful when you need to modify the collection during iteration.

Syntax:

Iterator<Type> iterator = hashSet.iterator();
while (iterator.hasNext()) {
    Type element = iterator.next();
    // Process element
}

• Explanation:
  • hashSet.iterator() returns an Iterator for the set.
  • hasNext() checks if there are more elements.
  • next() retrieves the next element in the iteration.

Example:

Example Explanation:

• Iterator Creation:
  • An iterator is obtained by calling iterator() on the colors HashSet.
• Iteration Process:
  • The while loop uses hasNext() to check for more elements.
  • The next() method retrieves each element in turn, which is then printed.
• Outcome:
  • The output displays all elements from the HashSet, with complete control over the iteration process.

Both methods enable you to process each element in a HashSet, even though the set does not guarantee a specific order. Understanding these iteration techniques is essential for working with sets in Java, allowing you to efficiently access and manipulate unique collections of data.