64 lines
1.9 KiB
Java
64 lines
1.9 KiB
Java
//: containers/References.java
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// ©2015 MindView LLC: see Copyright.txt
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// Demonstrates Reference objects
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import java.lang.ref.*;
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import java.util.*;
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class VeryBig {
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private static final int SIZE = 10000;
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private long[] la = new long[SIZE];
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private String ident;
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public VeryBig(String id) { ident = id; }
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@Override
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public String toString() { return ident; }
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@Override
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protected void finalize() {
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System.out.println("Finalizing " + ident);
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}
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}
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public class References {
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private static ReferenceQueue<VeryBig> rq =
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new ReferenceQueue<>();
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public static void checkQueue() {
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Reference<? extends VeryBig> inq = rq.poll();
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if(inq != null)
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System.out.println("In queue: " + inq.get());
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}
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public static void main(String[] args) {
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int size = 10;
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// Or, choose size via the command line:
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if(args.length > 0)
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size = new Integer(args[0]);
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LinkedList<SoftReference<VeryBig>> sa =
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new LinkedList<>();
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for(int i = 0; i < size; i++) {
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sa.add(new SoftReference<>(
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new VeryBig("Soft " + i), rq));
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System.out.println("Just created: " + sa.getLast());
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checkQueue();
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}
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LinkedList<WeakReference<VeryBig>> wa =
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new LinkedList<>();
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for(int i = 0; i < size; i++) {
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wa.add(new WeakReference<>(
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new VeryBig("Weak " + i), rq));
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System.out.println("Just created: " + wa.getLast());
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checkQueue();
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}
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SoftReference<VeryBig> s =
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new SoftReference<>(new VeryBig("Soft"));
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WeakReference<VeryBig> w =
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new WeakReference<>(new VeryBig("Weak"));
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System.gc();
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LinkedList<PhantomReference<VeryBig>> pa =
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new LinkedList<>();
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for(int i = 0; i < size; i++) {
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pa.add(new PhantomReference<>(
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new VeryBig("Phantom " + i), rq));
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System.out.println("Just created: " + pa.getLast());
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checkQueue();
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}
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}
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} /* (Execute to see output) *///:~
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