Java Collection Class and Final, Finally, Finalize

The Collection Framework in Java provides a set of classes and interfaces to store and manipulate a group of objects efficiently. It is part of the java.util package.

Objectives of Collection Framework

• To represent a group of objects as a single unit.
• To provide ready-made data structures like List, Set, and Map.
• To improve code reusability and performance.

Advantages

• Reduces development time with reusable data structures.
• Provides dynamic storage (no fixed size like arrays).
• Supports algorithms like sorting and searching easily.

Common Interfaces and Classes

• List Interface: ArrayList, LinkedList, Vector
• Set Interface: HashSet, LinkedHashSet, TreeSet
• Map Interface: HashMap, TreeMap, LinkedHashMap

Example – Using ArrayList


import java.util.*;

public class Example {
  public static void main(String[] args) {
    ArrayList list = new ArrayList<>();
    list.add("Java");
    list.add("Python");
    list.add("C++");
    System.out.println(list);
  }
}

Final, Finally, and Finalize in Java

These three keywords look similar but serve completely different purposes in Java:

Final

Used to declare constants, prevent inheritance, or stop method overriding.

final int MAX = 100;

Finally

Used in exception handling to execute important code whether exception occurs or not.


try {
  int data = 50 / 0;
} catch (Exception e) {
  System.out.println(e);
} finally {
  System.out.println("Finally block executed");
}

Finalize

Used to perform cleanup operations before garbage collection.


protected void finalize() {
  System.out.println("Finalize called before object deletion");
}

Differences Between Final, Finally, and Finalize

Best Practices

Keyword	Usage	Belongs To
final	Constant / Prevent inheritance	Variable, Method, Class
finally	Used for cleanup code	Exception Handling
finalize	Called before object destruction	Object Class

• Use Final keyword for constants and security.
• Always close resources in Finally block.
• Avoid relying on Finalize; use try-with-resources instead.