List

• ArrayList

  • It internally uses an array

  • Fast to access the elements by index

  • Slower if you want to do operations in the middle

• LinkedList

  • Based on a Double Linked

  • Very fast for deleting or adding elements in the middle

• Vector

  • It belongs to the legacy

  • Synchronized

• Stack

  • It basically implements a stack.

Queue

• PrioritQueue

  • Implements a Queue

• ArrayDeque

  • Implements a Queue, but allows us to do operations at the bottom and at the top

Set

• HashSet

  • Doesn't allow duplications

  • Doesn't keep the order of insertion

• LinkedHashSet(Log(1))

  • Keep the order of insertion

• TreeSet(Log(n))

  • It sorts the elements using the natural order

Map

• HashMap

  • Unsorted keys

  • A pair of keys and values.

  • Allows null values at the key

• LinkedHashMap

  • Maintain the insertion order

• HashTable

  • The same as HashMap, but it is synchronized

  • Slower than HashMap

  • Belongs to the legacy of Java. Try to not use this

• TreeMap

  • The key is sorted using the natural order of the Keys.

  • Also, you can implement your own sort order