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import java.lang.ref.PhantomReference;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.HashMap;
public class Main {
public static void main(String[] args) {
ReferenceQueue referenceQueue = new ReferenceQueue();
Object object = new Object() {
public String toString() {
return "Referenced Object";
}
};
Object data = new Object() {
public String toString() {
return "Data";
}
};
HashMap map = new HashMap();
Reference reference = null;
System.out.println("Testing PhantomReference.");
reference = new PhantomReference(object, referenceQueue);
map.put(reference, data);
System.out.println(reference.get());
System.out.println(map.get(reference));
System.out.println(reference.isEnqueued());
System.gc();
System.out.println(reference.get());
System.out.println(map.get(reference));
System.out.println(reference.isEnqueued());
object = null;
data = null;
System.gc();
System.out.println(reference.get());
System.out.println(map.get(reference));
System.out.println(reference.isEnqueued());
}
}
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