Java codestyle & tipstricks

Java Code Conventions Java Tips & Tricks Italtel, Italtel logo and iMSS (Italtel Multi-Service Solutions) are registered trademarks owned by Italtel S.p.A. All other trademarks mentioned in this document are property of their respective owners. Italtel S.p.A. cannot guarantee the accuracy of the information presented, which may change without notice. All contents are © Copyright 2006 Italtel S.p.A. - All rights reserved. Domenico Briganti

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style ,[object Object],[object Object]

Java Code Style 1/10 ,[object Object],[object Object],[object Object],Dominio Progetto Modulo

Java Code Style 2/10 ,[object Object],[object Object],[object Object],[object Object]

Numeri ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C Con lo “0” davanti, il numero è un ottale.

Java Code Style 3/10 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style 4/10 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style 5/10 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Operazione aritmetiche ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C

Java Code Style 6/10 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style 7/10 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style 8/10 ,[object Object],[object Object],[object Object],[object Object],[object Object]

Stringhe ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],A

Java Code Style 9/10 ,[object Object],[object Object],[object Object],[object Object]

Java Code Style 10/10 ,[object Object],[object Object],[object Object]

Java Code Style Riepilogo ,[object Object],[object Object],[object Object],[object Object]

Java Code Style Tools ,[object Object],[object Object],[object Object]

Java Code Style DEMO Classe sottoposta alla verifica ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java Code Style DEMO Risulatato della verifica

Debug Remoto (JPDA) - Demo ,[object Object],[object Object],[object Object],[object Object],[object Object]

Ant con JUnit Cobertura e CheckStyle ,[object Object]

FindBug e PDM ,[object Object],[object Object],[object Object],[object Object]

Java Tips & Tricks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

La gerarchia di classe delle eccezioni Object Throwable Error Exception LinkageError Virtual MachineError AWTError RuntimeException ClassNotFoundException NullPointerException IndexOutOfBoundException ArthemticException NoSuchMethodException Eccezioni non controllate

Eccezioni checked e unchecked ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Catch annidati e blocco finally ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],9

Exception propagation main() : … demo.level1() … level1() : … try{ … level2() …} catch( ArithmeticException p) {…} …. level2() : … level3() … level3() : … c = c / 0; // divided by zero … normal flow exception flow

C’è qualcosa che non va nel codice sotto? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Quando usare le eccezioni ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Gestione della memoria e Memory Leak Java Memory leak Allocated Reachable Live Handled by JVM

UnsupportedClassVersionError (Unsupported major.minor version 49.0) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Metodo equals ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],@Override public boolean equals(Object obj) { if (obj instanceof MioValore) { MioValore valore = (MioValore) obj; if (valore.val1.equals(val1) && valore.val2.equals(val2)) return true ; } return false ; } Quale risultato si ottiene? Come Procedere in questo caso?

Metodo Clone – Shallow copy e deep copy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Clone = {(“ The quick brown fox jumps over the lazy dog ”)}

Argomenti a linea di comando ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) AnyProg b) Well c) Done d)ArrayIndexOutOfBoundException Risultato? D

StringBuilder ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Keyword synchronized ,[object Object],[object Object],[object Object],[object Object],B

Thread ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],D

Overloading ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C

Polimorfismo ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C

Sovrascrittura di metodi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) Errore qui b) Errore qui c) Runtime Exception Risultato? B

Interfacce ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Classi e variabili Final ,[object Object],[object Object],[object Object]

Costruttori ,[object Object],[object Object],[object Object],[object Object],[object Object],B

Ereditarietà ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) C,B,B,Main b) Main,A,C,B c) Main,A,B,C d) Main,A,B,A Risultato? B

Switch ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) Output “default” b) Output “10 20” c) Non compila d) Nessuna di queste Risultato? B

Garbage Collection ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C

Passaggio per Valore o per Riferimento ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) 15 0 20 b) 15 0 15 c) 20 0 20 d) 0 15 20 Risultato? A

Assegnamento ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Risultato? 3

Instanze di oggetti e campi statici ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],a) Output “SCJP” x 2 b) Output “SCJP” c) Non compila d) NullPointerExc… Risultato? A

Cosa e’ un pattern? 1/2 ,[object Object],[object Object],[object Object]

Cosa e’ un pattern? 2/2 ,[object Object],[object Object],[object Object],[object Object]

Classificazione 1/2 ,[object Object],[object Object],[object Object]

Classificazione 2/2 ,[object Object],[object Object],[object Object]

Observer 1/3 ,[object Object],[object Object],[object Object],[object Object]

Observer 3/3 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Factory 1/4 ,[object Object],[object Object],[object Object]

Factory 3/4 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Proxy 1/4 ,[object Object],[object Object],[object Object]

Proxy 3/4 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Proxy 4/4 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Più interfacce sulla stessa macchina ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Java codestyle & tipstricks

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