62 lines
1.5 KiB
Java
62 lines
1.5 KiB
Java
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//: polymorphism/ReferenceCounting.java
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// <20>2015 MindView LLC: see Copyright.txt
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// Cleaning up shared member objects.
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import static com.mindviewinc.util.Print.*;
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class Shared {
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private int refcount = 0;
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private static long counter = 0;
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private final long id = counter++;
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public Shared() {
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print("Creating " + this);
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}
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public void addRef() { refcount++; }
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protected void dispose() {
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if(--refcount == 0)
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print("Disposing " + this);
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}
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@Override
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public String toString() { return "Shared " + id; }
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}
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class Composing {
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private Shared shared;
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private static long counter = 0;
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private final long id = counter++;
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public Composing(Shared shared) {
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print("Creating " + this);
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this.shared = shared;
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this.shared.addRef();
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}
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protected void dispose() {
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print("disposing " + this);
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shared.dispose();
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}
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@Override
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public String toString() { return "Composing " + id; }
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}
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public class ReferenceCounting {
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public static void main(String[] args) {
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Shared shared = new Shared();
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Composing[] composing = { new Composing(shared),
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new Composing(shared), new Composing(shared),
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new Composing(shared), new Composing(shared) };
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for(Composing c : composing)
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c.dispose();
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}
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} /* Output:
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Creating Shared 0
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Creating Composing 0
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Creating Composing 1
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Creating Composing 2
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Creating Composing 3
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Creating Composing 4
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disposing Composing 0
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disposing Composing 1
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disposing Composing 2
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disposing Composing 3
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disposing Composing 4
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Disposing Shared 0
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*///:~
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