Name four Container classes.

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Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane.

In Core Java, container classes typically refer to classes that hold and manage other objects. Here are four container classes in Java:

  1. ArrayList: It’s a dynamic array implementation of the List interface, allowing the dynamic resizing of the array as elements are added or removed.
java
List<String> list = new ArrayList<>();
  1. LinkedList: It’s a doubly-linked list implementation of the List interface, providing fast insertion and deletion but slower random access compared to ArrayList.
java
List<String> linkedList = new LinkedList<>();
  1. HashMap: It’s an implementation of the Map interface, using a hash table to store key-value pairs. It provides fast retrieval and insertion.
java
Map<String, Integer> hashMap = new HashMap<>();
  1. HashSet: It’s an implementation of the Set interface, using a hash table to store unique elements. It does not allow duplicate elements.
java
Set<String> hashSet = new HashSet<>();

These classes are part of the Java Collections Framework and are commonly used for storing and managing groups of objects.