Difference Between `final`, `finally`, and `finalize()` in Java

These three terms look similar but serve completely different purposes in Java. This is a very common interview question.

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🔹 1. final Keyword

final is a keyword used to restrict modification.

Uses of final

• Final Variable → Value cannot be changed (constant)
• Final Method → Cannot be overridden
• Final Class → Cannot be inherited

Example

final int x = 10;
// x = 20; ❌ Error (cannot change value)

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🔹 2. finally Block

finally is a block used in exception handling.
It always executes whether an exception occurs or not.

Purpose

• Close resources
• Database connections cleanup
• File handling cleanup

Example

try {
    int a = 10 / 0;
} catch (Exception e) {
    System.out.println("Exception handled");
} finally {
    System.out.println("Finally block executed");
}

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🔹 3. finalize() Method

finalize() is a method called by the Garbage Collector before destroying an object.

Purpose

• Perform cleanup before object removal
• Release system resources

Example

class Test {
    protected void finalize() {
        System.out.println("Object destroyed");
    }
}

⚠️ Note: finalize() is deprecated in modern Java versions and should generally be avoided.

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🔹 Key Differences

Feature	final	finally	finalize()
Type	Keyword	Block	Method
Used In	Variables, Methods, Classes	Exception Handling	Garbage Collection
Purpose	Restrict modification	Always execute cleanup code	Cleanup before object removal
Execution Time	Compile time rule	After try/catch	Before GC removes object

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✅ Easy Interview Line

• final → restriction
• finally → always executes
• finalize() → called by Garbage Collector

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