Gestione delle eccezioni Individuazione e ripristino parseint Individuazione e ripristino Individuazione e ripristino parseint

Transcript

1 parseint parseint

2 showinputdialog JOptionPanenull null

3 throw BankAccount IllegalArgumentException amount

4 public class BankAccount { public void withdraw(double amount) { if (balance < amount) { // Parametro amount troppo grande IllegalArgumentException exception = new IllegalArgumentException( Richiesta maggiore del saldo ); throw exception; // Se arrivo qui posso fare l'operazione public class BankAccount { public void withdraw(double amount) { if (balance < amount) { // Parametro amount troppo grande throw new IllegalArgumentException( Amount exceedes balance ); // Faccio l'operazione balance -= amount;... throw return readline BufferedReader null EOFException

5 EOFEXception IOException Exception RuntimeException RuntimeException java.lang.exception ErrorOutOfMemoryError java.lang.throwable

6 NullPointerException NumberFormatException parseint parsedouble readline BufferedReader IOException readline BufferedReader readline

7 throws public class Coin { public void read(bufferedreader in) throws IOException { value = Double.parseDouble( in.readline()); name = in.readline();...

8 public class Purse { public void read(bufferedreader in) throws IOException { while (...) { Coin c = new Coin(); // read di Coin rilancia! c.read(in); add(c);... readcoin readlinebufferedreader IOException throws readpurse readcoin IOException throws public void m() throws IOException, ClassNotFoundException {... read IOException

9 null if (amount > balance) throw new InsufficientFundsException( withdrawal of + amount + exceeds balance of + balance); else... InsufficientFundsException

10 withdraw RuntimeException public class InsufficientFundsException extends RuntimeException { public InsufficientFundsException() { // Costruttore senza parametri public InsufficientFundsException( String reason) { super(reason); // chiamo il // costruttore della superclasse String reason

11 trycatch try catchtry catch catch try-catch try { BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); System.out.println( How old are you? ); String inputline = in.readline(); int age = Integer.parseInt(inputLine); age++; System.out.println( Next year you ll be + age); catch (IOException exception) { System.out.println( Input/Output exception + exception); catch (NumberFormatException exception) { System.out.println( Input was not a number ); IOException readlinenumberformatexception parseint NumberFormatException

12 catch( e) try e try printstacktrace() try ThrowableException Error catch(exception e) catch (Throwable t) finally try-catch finally

13 BufferedReader in = null; try { in = new BufferedReader( new FileReader(fileName)); purse.read(in); finally { if (in!= null) in.close(); NumberFormatException main

14 public boolean read(bufferedreader in) throws IOException { String input = in.readline(); if (input == null) // Non ci sono più monete da leggere // Segnalo con false in uscita return false; value = Double.parseDouble(input); name = in.readline() if (name == null) // Situazione anomala non prevista! throw new EOFException( Coin name expected ); return true; IOException readline() EOFException false EOFException public void read( BufferedReader in) throws IOException { boolean done = false; while (!done) { Coin c = new Coin(); if (c.read(in)) add(c); else done = true; IOException readcoin

15 public void readfile(string filename) throws IOException { BufferedReader in = null; try { in = new BufferedReader( new FileReader(fileName)); read(in) finally { if (in!= null) in.close() read boolean done = false; String filename = JOptionPane.showInputDialog( Enter File name ); while(!done) { try { Purse mypurse = new Purse(); mypurse.readfile(filename); System.out.println( Total: + mypurse.gettotal()); done = true; catch (IOException e) { System.out.println( Input/Output error: + e); catch (NumberFormatException e) { e.printstacktrace(); if (!done) { filename = JOptionPane.showInputDialog( Try another file or Cancel to exit ); if (filename == null) done = true;

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