LazyCleaner

This project implements an object cleaner for Java 6 (and later). It provides similar feature as Java 9's java.lang.ref.Cleaner but compatible with Java 6+. The main difference is that this library defaults to lazy cleaner thread creation and, more importantly, the thread is terminated if no objects are being tracked for threadTtl milliseconds.

Usage

To use it, add this dependency in you pom.xml:

<dependency>
    <groupId>net.juanlopes.lazycleaner</groupId>
    <artifactId>lazycleaner</artifactId>
    <version>1.1.0</version>
</dependency>  

Then, add it to your resource class like the following:

public class Resource implements Closeable {
    // creates a LazyCleaner instance with a thread TTL of 30 seconds
    private static final LazyCleaner CLEANER = new LazyCleaner(30000, "Resource Cleaner");

    private final LazyCleaner.Cleanable cleanable;

    public Resource() {
        // make sure Disposer is static, otherwise it will keep a reference to this
        this.cleanable = CLEANER.register(this, new Disposer());
    }

    @Override
    public void close() {
        cleanable.clean();
    }

    private static class Disposer implements LazyCleaner.CleaningAction {
        @Override
        public void onClean(boolean leak) throws Exception {
            System.out.println("Cleaning Resource. Did it leak? " + leak);
        }
    }
}

If you want to eagerly start the cleaning thread, initialize your LazyCleaner like the following:

new LazyCleaner(30000, "Resource Cleaner").setKeepThreadAlive(true);