Java Collections Framework & Time Complexity Of Operations
Abid Anjum
Senior Full Stack Developer Architect | Java Spring Boot Microservices | Angular & React | Mobile Apps Engineer Android IOS Flutter | Asp.net Core C# | BI Expert | GIS Expertise
1. ArrayList
It is used for fast random access and is mainly for storing and accessing data sequentially.
Great for scenarios where you frequently need to access elements by index and the order of elements is important.
Time Complexity
? get: O(1)
? add: O(1)
? remove: O(n)
2. LinkedList
Use for frequent insertions and deletions in the middle of the list.
Also useful when the order of elements is important
Time Complexity
? get: O(n)
? add: O(1)
? remove: O(1)
? contains: O(n)
3. HashSet
Use when you need to store a unique set of elements and perform fast lookups for element existence.
It's great for checking for duplicates.
Time Complexity
? add: O(1)
? remove: O(1)
? contains: O(1)
4. TreeSet
When you need to store a sorted set of unique elements.
Time Complexity
? add: O(log n)
? remove: O(log n)
? contains: O(log n)
5. HashMap
Use when you need to store key-value pairs and quickly look up values based on keys.
Time Complexity
? put: O(1)
? remove: O(1)
? contains: O(1)
6. TreeMap
Use when you need to store key-value pairs in a sorted order based on the keys
Time Complexity
? put: O(log n)
? remove: O(log n)
? contains: O(log n)