java大学程序设计和java大学基础教程的例子---缺的---ch14

// Fig. 14.14: CreditInquiry.java // This program reads a file sequentially and displays the // contents based on the type of account the user requests // (credit balance, debit balance or zero balance). import java.io.File; import java.io.FileNotFoundException; import java.lang.IllegalStateException; import java.util.NoSuchElementException; import java.util.Scanner; import com.deitel.jhtp7.ch14.AccountRecord; public class CreditInquiry { private MenuOption accountType; private Scanner input; private MenuOption choices[] = { MenuOption.ZERO_BALANCE, MenuOption.CREDIT_BALANCE, MenuOption.DEBIT_BALANCE, MenuOption.END }; // read records from file and display only records of appropriate type private void readRecords() { // object to be written to file AccountRecord record = new AccountRecord(); try // read records { // open file to read from beginning input = new Scanner( new File( "clients.txt" ) ); while ( input.hasNext() ) // input the values from the file { record.setAccount( input.nextInt() ); // read account number record.setFirstName( input.next() ); // read first name record.setLastName( input.next() ); // read last name record.setBalance( input.nextDouble() ); // read balance // if proper acount type, display record if ( shouldDisplay( record.getBalance() ) ) System.out.printf( "%-10d%-12s%-12s%10.2f\n", record.getAccount(), record.getFirstName(), record.getLastName(), record.getBalance() ); } // end while } // end try catch ( NoSuchElementException elementException ) { System.err.println( "File improperly formed." ); input.close(); System.exit( 1 ); } // end catch catch ( IllegalStateException stateException ) { System.err.println( "Error reading from file." ); System.exit( 1 ); } // end catch catch ( FileNotFoundException fileNotFoundException ) { System.err.println( "File cannot be found." ); System.exit( 1 ); } // end catch finally { if ( input != null ) input.close(); // close the Scanner and the file } // end finally } // end method readRecords // use record type to determine if record should be displayed private boolean shouldDisplay( double balance ) { if ( ( accountType == MenuOption.CREDIT_BALANCE ) && ( balance < 0 ) ) return true; else if ( ( accountType == MenuOption.DEBIT_BALANCE ) && ( balance > 0 ) ) return true; else if ( ( accountType == MenuOption.ZERO_BALANCE ) && ( balance == 0 ) ) return true; return false; } // end method shouldDisplay // obtain request from user private MenuOption getRequest() { Scanner textIn = new Scanner( System.in ); int request = 1; // display request options System.out.printf( "\n%s\n%s\n%s\n%s\n%s\n", "Enter request", " 1 - List accounts with zero balances", " 2 - List accounts with credit balances", " 3 - List accounts with debit balances", " 4 - End of run" ); try // attempt to input menu choice { do // input user request { System.out.print( "\n? " ); request = textIn.nextInt(); } while ( ( request < 1 ) || ( request > 4 ) ); } // end try catch ( NoSuchElementException elementException ) { System.err.println( "Invalid input." ); System.exit( 1 ); } // end catch return choices[ request - 1 ]; // return enum value for option } // end method getRequest public void processRequests() { // get user's request (e.g., zero, credit or debit balance) accountType = getRequest(); while ( accountType != MenuOption.END ) { switch ( accountType ) { case ZERO_BALANCE: System.out.println( "\nAccounts with zero balances:\n" ); break; case CREDIT_BALANCE: System.out.println( "\nAccounts with credit balances:\n" ); break; case DEBIT_BALANCE: System.out.println( "\nAccounts with debit balances:\n" ); break; } // end switch readRecords(); accountType = getRequest(); } // end while } // end method processRequests } // end class CreditInquiry /************************************************************************* * (C) Copyright 1992-2007 by Deitel & Associates, Inc. and * * Pearson Education, Inc. All Rights Reserved. * * * * DISCLAIMER: The authors and publisher of this book have used their * * best efforts in preparing the book. These efforts include the * * development, research, and testing of the theories and programs * * to determine their effectiveness. The authors and publisher make * * no warranty of any kind, expressed or implied, with regard to these * * programs or to the documentation contained in these books. The authors * * and publisher shall not be liable in any event for incidental or * * consequential damages in connection with, or arising out of, the * * furnishing, performance, or use of these programs. * *************************************************************************/