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標 題繼承和finalize()的問題
發信站無名小站 (Sat Feb 25 19:54:11 2006)
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以下是Thinking in Java中譯本當中P333~335的code
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() throws Throwable{
System.out.println("LivingCreature finalize");
if(DoBaseFinalization.flag)
super.finalize();
}
}
class Animal extends LivingCreature{
Characteristic p =new Characteristic("hac heart");
Animal(){
System.out.println("Anaimal()");
}
protected void finalize() throws Throwable{
System.out.println("Animal finalize");
if(DoBaseFinalization.flag)
super.finalize();
}
}
class Amphibian extends Animal{
Characteristic p =new Characteristic("can live in water");
Amphibian(){
System.out.println("Amphibian()");
}
protected void finalize() throws Throwable{
System.out.println("Amphibian finalize");
if (DoBaseFinalization.flag)
super.finalize();
}
}
public class Frog extends Amphibian {
Frog(){
System.out.println("Frog()");
}
protected void finalize() throws Throwable{
System.out.println("Frog finalize");
if(DoBaseFinalization.flag)
super.finalize();
}
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();
System.out.println("Bye!!");
System.gc();
}
}
然後執行所得的結果如下：
Not finalizing bases
Creating Characteristic is alive
LivingCreature()
Creating Characteristic has heart
Animal()
Creating Characteristic can live in water
Amphibian()
Frog()
Bye!
finalizing Characteristic can live in water
finalizing Characteristic has heart
finalizing Characterisitc is alive
Frog finalize
在此提出幾個問題，多謝指導!!
1.System.gc之後的動作會呼叫finalize()，但帶有extends的關係中，順序是什麼呢？
2.在該本書中的執行結果為，請問是不是有誤呢？
(上面略)
Bye!
Frog finalize
finalizing Characterisitc is alive
finalizing Characteristic has heart
finalizing Characteristic can live in water
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