Merging Java Lists: A Comprehensive Guide
When working with Java, combining multiple lists into one can be a crucial task. Fortunately, Java provides several ways to achieve this, each with its own advantages. Let’s dive into three distinct methods to merge Java lists.
Method 1: Using addAll()
The addAll() method is a part of the List interface and is perhaps the most straightforward way to combine two lists. By calling addAll() on the target list and passing the source list as an argument, you can merge the two lists effortlessly.
Example 1: Merging Lists with addAll()
In this example, we’ll create two lists, list1 and list2, and then use addAll() to merge them into a new list called joined.
Output:
The resulting joined list will contain all elements from both list1 and list2.
Method 2: Utilizing union()
Another approach to merge lists is by using the union() method. This method returns a new list containing all elements from both input lists.
Example 2: Merging Lists with union()
In this example, we’ll use the union() method to combine list1 and list2 into a new list called joined.
Output:
The resulting joined list will contain all elements from both list1 and list2, identical to the previous example.
Method 3: Leveraging Java Streams
For a more modern approach, you can utilize Java Streams to merge lists. By converting the lists to streams, concatenating them using concat(), and then collecting the result back into a list, you can achieve the same outcome.
Example 3: Merging Lists with Java Streams
In this example, we’ll use Java Streams to merge list1 and list2 into a new list called joined.
Output:
The resulting joined list will contain all elements from both list1 and list2, identical to the previous examples.
Further Reading
If you’re interested in exploring more Java programming topics, be sure to check out our guides on merging two lists and calculating the union of two sets.