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Garbage.javaAPI DocExample3932Mon Apr 06 18:10:26 BST 1998None

Garbage.java

//: Garbage.java
//////////////////////////////////////////////////
// Copyright (c) Bruce Eckel, 1998
// Source code file from the book "Thinking in Java"
// All rights reserved EXCEPT as allowed by the
// following statements: You can freely use this file
// for your own work (personal or commercial),
// including modifications and distribution in
// executable form only. Permission is granted to use
// this file in classroom situations, including its
// use in presentation materials, as long as the book
// "Thinking in Java" is cited as the source. 
// Except in classroom situations, you cannot copy
// and distribute this code; instead, the sole
// distribution point is http://www.BruceEckel.com 
// (and official mirror sites) where it is
// freely available. You cannot remove this
// copyright and notice. You cannot distribute
// modified versions of the source code in this
// package. You cannot use this file in printed
// media without the express permission of the
// author. Bruce Eckel makes no representation about
// the suitability of this software for any purpose.
// It is provided "as is" without express or implied
// warranty of any kind, including any implied
// warranty of merchantability, fitness for a
// particular purpose or non-infringement. The entire
// risk as to the quality and performance of the
// software is with you. Bruce Eckel and the
// publisher shall not be liable for any damages
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// Bruce Eckel or the publisher be liable for any
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// address for non-code errors found in the book.)
/////////////////////////////////////////////////

// Demonstration of the garbage
// collector and finalization

class Chair {
  static boolean gcrun = false;
  static boolean f = false;
  static int created = 0;
  static int finalized = 0;
  int i;
  Chair() {
    i = ++created;
    if(created == 47) 
      System.out.println("Created 47");
  }
  protected void finalize() {
    if(!gcrun) {
      gcrun = true;
      System.out.println(
        "Beginning to finalize after " +
        created + " Chairs have been created");
    }
    if(i == 47) {
      System.out.println(
        "Finalizing Chair #47, " +
        "Setting flag to stop Chair creation");
      f = true;
    }
    finalized++;
    if(finalized >= created)
      System.out.println(
        "All " + finalized + " finalized");
  }
}

public class Garbage {
  public static void main(String[] args) {
    if(args.length == 0) {
      System.err.println("Usage: \n" +
        "java Garbage before\n  or:\n" +
        "java Garbage after");
      return;
    }
    while(!Chair.f) {
      new Chair();
      new String("To take up space");
    }
    System.out.println(
      "After all Chairs have been created:\n" +
      "total created = " + Chair.created +
      ", total finalized = " + Chair.finalized);
    if(args[0].equals("before")) {
      System.out.println("gc():");
      System.gc();
      System.out.println("runFinalization():");
      System.runFinalization();
    }
    System.out.println("bye!");
    if(args[0].equals("after"))
      System.runFinalizersOnExit(true);
  }
} ///:~