42 lines
1.0 KiB
Java
42 lines
1.0 KiB
Java
// housekeeping/TerminationCondition.java
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// (c)2020 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Using finalize() to detect an object that
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// hasn't been properly cleaned up
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import onjava.*;
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class Book {
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boolean checkedOut = false;
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Book(boolean checkOut) {
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checkedOut = checkOut;
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}
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void checkIn() {
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checkedOut = false;
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}
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@SuppressWarnings("deprecation")
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@Override
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public void finalize() {
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if(checkedOut)
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System.out.println("Error: checked out");
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// Normally, you'll also do this:
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// super.finalize(); // Call the base-class version
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}
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}
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public class TerminationCondition {
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public static void main(String[] args) {
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Book novel = new Book(true);
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// Proper cleanup:
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novel.checkIn();
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// Drop the reference, forget to clean up:
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new Book(true);
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// Force garbage collection & finalization:
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System.gc();
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new Nap(1); // One second delay
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}
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}
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/* Output:
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Error: checked out
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*/
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