//: Frog.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 // suffered by you or any third party as a result of // using or distributing software. In no event will // Bruce Eckel or the publisher be liable for any // lost revenue, profit, or data, or for direct, // indirect, special, consequential, incidental, or // punitive damages, however caused and regardless of // the theory of liability, arising out of the use of // or inability to use software, even if Bruce Eckel // and the publisher have been advised of the // possibility of such damages. Should the software // prove defective, you assume the cost of all // necessary servicing, repair, or correction. If you // think you've found an error, please email all // modified files with clearly commented changes to: // Bruce@EckelObjects.com. (Please use the same // address for non-code errors found in the book.) ///////////////////////////////////////////////// // Testing finalize with inheritance class DoBaseFinalization { public static boolean flag = false; } class Characteristic { String s; Characteristic(String c) { s = c; System.out.println( "Creating Characteristic " + s); } protected void finalize() { System.out.println( "finalizing Characteristic " + s); } } class LivingCreature { Characteristic p = new Characteristic("is alive"); LivingCreature() { System.out.println("LivingCreature()"); } protected void finalize() { System.out.println( "LivingCreature finalize"); // Call base-class version LAST! if(DoBaseFinalization.flag) try { super.finalize(); } catch(Throwable t) {} } } class Animal extends LivingCreature { Characteristic p = new Characteristic("has heart"); Animal() { System.out.println("Animal()"); } protected void finalize() { System.out.println("Animal finalize"); if(DoBaseFinalization.flag) try { super.finalize(); } catch(Throwable t) {} } } class Amphibian extends Animal { Characteristic p = new Characteristic("can live in water"); Amphibian() { System.out.println("Amphibian()"); } protected void finalize() { System.out.println("Amphibian finalize"); if(DoBaseFinalization.flag) try { super.finalize(); } catch(Throwable t) {} } } public class Frog extends Amphibian { Frog() { System.out.println("Frog()"); } protected void finalize() { System.out.println("Frog finalize"); if(DoBaseFinalization.flag) try { super.finalize(); } catch(Throwable t) {} } public static void main(String[] args) { if(args.length != 0 && args[0].equals("finalize")) DoBaseFinalization.flag = true; else System.out.println("not finalizing bases"); new Frog(); // Instantly becomes garbage System.out.println("bye!"); // Must do this to guarantee that all // finalizers will be called: System.runFinalizersOnExit(true); } } ///:~