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Jun 23, 2009 · A set is an unordered group of distinct objects — no duplicate objects are allowed. It is generally implemented using the hash code of the objects being inserted. (Specific implementations may add ordering, but the Set interface itself does not.) A list is an ordered group of objects which may contain duplicates.
Apr 29, 2022 · Difference Between List and Set in Java. Last Updated : 29 Apr, 2022. The List interface allows storing the ordered collection. It is a child interface of Collection. It is an ordered collection of objects in which duplicate values are allowed to store.
Nov 26, 2018 · The set() method of java.util.ArrayList class is used to replace the element at the specified position in this list with the specified element. Syntax: public E set(int index, E element)
- Overview
- Conceptual Difference
- Code Example
- Performance Comparison Between List and Set
- Memory Allocation Comparison Between List and Set
- Conclusion
In this tutorial, we’ll discuss the differences between Set and List in Javawith the help of a simple example. Also, we’ll compare the two data structures in terms of performance and memory allocation.
Both List and Set are members of Java Collections. However, there are a few important differences: 1. A List can contain duplicates, but a Setcan’t 2. A List will preserve the order of insertion, but a Setmay or may not 3. Since insertion order may not be maintained in a Set, it doesn’t allow index-based access as in the List Please note that there...
3.1. Allowing Duplicates
Adding a duplicate item is allowed for a List. However, it isn’t for a Set:
3.2. Maintaining Insertion Order
A Set maintains order depending on the implementation. For example, a HashSet is not guaranteed to preserve order, but a LinkedHashSet is. Let’s see an example of ordering with LinkedHashSet: Since a Setis not guaranteed to maintain order, it can’t be indexed.
Let’s compare the performance of the List and Set data structures using the Java Microbench Harness (JMH). First, we’ll create two classes: ListAndSetAddBenchmark and ListAndSetContainBenchmark. Then, we’ll measure the execution time for add() and contains() methods for the List and Setdata structures.
In the previous section, we saw different metrics that measure the performance of List and Set with respect to time. Let’s measure the memory allocation for the benchmark methods by specifying the gc profiler option “-prof gc” while running the benchmark. Let’s modify the main()method and configure the JMH run options for the two benchmark classes:...
In this article, we learned the difference between a List and a Set in Java. Additionally, we saw a benchmark test to compare the performance of List and Set with respect to time and memory allocation. Depending on the use case, List and Set can be better for a specific operation. As always, the source code for the examples is available over on Git...
Jul 2, 2024 · The List interface is found in java.util package and inherits the Collection interface. It is a factory of the ListIterator interface. Through the ListIterator, we can iterate the list in forward and backward directions. The implementation classes of the List interface are ArrayList, LinkedList, Stack, and Vector.
Oct 11, 2015 · To set the value, you would take an ArrayList<String> passed as a parameter, and you would simply set the ArrayList to the parameter. Also, note the use of void rather than the ArrayList<String> shown in your question. Commonly, a setter method does not return anything.
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Jul 18, 2024 · In this Java list tutorial, I will help you understand the characteristics of list collections, how to use list implementations (ArrayList and LinkedList) in day-to-day programming and look at various examples of common programming practices when using lists.
