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/**
* Copyright (c) 2024 Araf Karsh Hamid
* <p>
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* <p>
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
* <p>
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
* <p>
* or (per the licensee's choosing)
* <p>
* under the terms of the Apache 2 License version 2.0
* as published by the Apache Software Foundation.
*/
package java18;
import java.util.Date;
import static java.lang.System.out;
/**
* JavaExamples / FinalizerExample
*
* JEP 421: Deprecate Finalization for Removal
*
* Java 18 deprecates the finalization mechanism for removal, which encourages developers to use
* alternative methods like AutoCloseable.
*
* Old Way: Using finalize()
*
* In the older Java versions, developers often used the finalize() method to release resources,
* such as closing a file or releasing memory. However, this approach has significant downsides,
* such as unpredictable timing of finalization and high overhead for garbage collection.
*
* New Way: Using AutoCloseable and try-with-resources
*
* Java 18 encourages developers to use AutoCloseable with try-with-resources to release
* resources deterministically and effectively, addressing the issues found with finalize().
*
* @author: Araf Karsh Hamid
* @version: 0.1
* @date: 2024-09-29T21:52
*/
public class FinalizerExample {
public static void main(String[] args) throws Exception {
// Java 18
out.println("JAVA 18 >>>>>--------------------------------------------------------");
var ofe = new OldFinalizerExample();
ofe.printResource();
ofe = null;
// Finalizer may or may not be called in a timely manner
System.gc();
try (var nfe = new NewFinalizerExample()) {
// Example usage of the resource
nfe.printResource();
}
// Resource is automatically closed when exiting the try-with-resources block
}
}
/**
* Old Finalizer Model
*/
class OldFinalizerExample {
private String resource;
public OldFinalizerExample() {
resource = "Old Finalizer Model...";
out.println(new Date()+" | Old Finalizer Model");
}
public void printResource() {
out.println(new Date()+" | Resource = "+resource);
}
/**
* finalize()
* • finalize() is invoked by the garbage collector just before an object is destroyed.
* • This method can be used to release resources, but it has major drawbacks:
* • Unpredictable timing: There’s no guarantee on when finalize() will be called.
* • Performance: The use of finalizers adds an overhead to garbage collection and can cause delays.
* • Memory Leaks: Objects with a finalize() method often take longer to be collected.
* @throws Throwable
*/
@Override
protected void finalize() throws Throwable {
try {
out.println(new Date()+" | Releasing resource in finalize: " + resource);
} finally {
super.finalize();
}
}
}
/**
* New Finalizer Model
*/
class NewFinalizerExample implements AutoCloseable {
private String resource;
public NewFinalizerExample() {
resource = "New Finalizer Model...";
out.println(new Date()+" | New Finalizer Model");
}
public void printResource() {
out.println(new Date()+" | Resource = "+resource);
}
/**
* - AutoCloseable Interface: Implementing AutoCloseable allows the object to be used in
* a try-with-resources block, where close() is called automatically at the end of the block.
* - try-with-resources: This construct ensures that the resource is closed automatically,
* which is deterministic and occurs immediately after the block is exited.
* - Clearer Lifecycle Management: Resources are properly closed as soon as they’re no
* longer needed, without relying on the unpredictable garbage collector behavior.
* @throws Exception
*/
@Override
public void close() throws Exception {
out.println(new Date()+" | Releasing resource in finalize: " + resource);
}
}