Difference between HashMap and LinkedHashMap

In Java, both LinkedHashMap and HashMap are used for key-value pair storage. However, there are some differences between them:

1. Ordering: HashMap does not maintain any order for the elements, while LinkedHashMap maintains the insertion order of the elements.
2. Performance: HashMap has better performance in terms of adding and searching elements, while LinkedHashMap has better performance when iterating over all elements.
3. Memory usage: LinkedHashMap uses slightly more memory than HashMap due to the need to maintain the order of the elements.
4. Concurrency: HashMap is not thread-safe, while LinkedHashMap can be made thread-safe by using Collections.synchronizedMap().

In summary, LinkedHashMap is more suitable when we need to maintain the order of elements or when we need to iterate over all elements frequently, while HashMap is more suitable when we need better performance in adding and searching elements.