Jonathan Lalou's Blog

Up to this day, I have coded in Java for more than 6 years. Of course, I enjoy Java, its compilation engine, and above all: with Java I need not handle pointers myself, which is a great progress (I suffered a trauma when I was younger, with C/C++ pointers).

Thanks to Java 5 (Tiger), many improvements are now available. Among them, the most I use are generics and the new for loop, ala foreach.

Nonetheless, I think Java lacks some features I encountered in other languages. Of course, I admit that implementing new features into such a complex project like the JVM is a hard issue. But I throw my ideas, may Sun developers feel free to accept or reject them.

• Multiple heritage is impossible.

• Default parameters values are unavailable:

public Toto(int i, String sz){   // do something } public Toto(){    this(0, “tata”); } public Toto(int i){    this(i, “tata”); } public Toto(String sz){    this(0, sz); }

In PHP (or Python), all these functions may be summed up to:

[php] function Toto(i = 0, sz = "tata"){   // do something } 

• Exception handling is too robust:

Let’s consider this function:

[java] public void toto() throws Exception1, Exception2, Exception3, Exception4{   // do something } 

Now, in Java we need to catch the exceptions like this:

[java] public void tata() throws Exception4{     try{ 	toto();     } catch(Exception1 e1){ 	e1.printStackTrace();     } catch(Exception2 e2){ 	e1.printStackTrace();     } catch(Exception2 e2){ 	e1.printStackTrace();     }     // throws the uncaught Exception4 } 

Obviously, we can catch a generic java.lang.Exception, but let’s acknowledge there is more elegant way :-(( I would like to have this code:

[java] public void tata() throws Exception4{     try{ 	toto();     } catch(Exception1, Exception2, Exception3 eee){ 	eee.printStackTrace();     }     // throws the uncatched Exception4 } 

J’ai installe le plugin de coloration syntaxique| pour DotClear.

Je dois dire que c’est pratique… et tres efficace:

[cpp] while (*p++=*q++); fprintf("toto %d", 18); 

[mysql] select * from toto where titi = 15 

Merci aux auteurs, je vais m’amuser comme un fou! 😉

Probleme rencontre ce matin en Java 5 (Tiger):

[java]
Vector toto = new Vector();
// ...remplissage du vecteur...
for (Object o : toto){
    toto.remove(o);
}

Cela leve une exception de type:
java.util.ConcurrentModificationException

Au debut j’ai pense a un probleme de synchronisation, et donc j’ai ajoute un bloc synchronized(mutex){...}, mais cela n’a pas fonctionne.
Mais en fait le probleme est different: apparemment cela vient de la facon dont le “foreach” a la Java gere le parcours des elements d’un vecteur (ou de tout autre objet iterable).

La solution que j’ai trouvee consiste a utiliser un “for” classique, qui fonctionne:

[java]
for (int i=0; i<toto.size(); i++){
    Object o = toto.elementAt(i);
    remove(o);
}

(je n’ai meme pas tente un remove(i), pour eviter les effets de bord sur les indices)
Neanmoins ce n’est pas ce qu’il y a de mieux, il aurait fallu utiliser un vrai Iterator, mais pour etre franc j’avais legerement la flemme…