写入和读取顺序文件

下面是文件结构

// Fig. 14.5: AccountRecord.java// A class that represents one record of information.public class AccountRecord{   private int account;   private String firstName;   private String lastName;   private double balance;      // no-argument constructor calls other constructor with default values   public AccountRecord()    {      this( 0, "", "", 0.0 ); // call four-argument constructor   } // end no-argument AccountRecord constructor     // initialize a record   public AccountRecord( int acct, String first, String last, double bal )   {      setAccount( acct );      setFirstName( first );      setLastName( last );      setBalance( bal );   } // end four-argument AccountRecord constructor   // set account number      public void setAccount( int acct )   {      account = acct;   } // end method setAccount   // get account number      public int getAccount()    {       return account;    } // end method getAccount      // set first name      public void setFirstName( String first )   {      firstName = first;   } // end method setFirstName   // get first name      public String getFirstName()    {       return firstName;    } // end method getFirstName      // set last name      public void setLastName( String last )   {      lastName = last;   } // end method setLastName   // get last name      public String getLastName()    {      return lastName;    } // end method getLastName      // set balance     public void setBalance( double bal )   {      balance = bal;   } // end method setBalance   // get balance      public double getBalance()    {       return balance;    } // end method getBalance} // end class AccountRecord

下面是创建

import java.io.*;import java.util.Formatter;import java.util.InputMismatchException;import java.util.Scanner;public class CreatTextFile {private Formatter textFile;public void creatFile(){try{textFile = new Formatter("test.txt");}catch (SecurityException e){System.out.println("you have no access to open this file");System.exit(1);}catch( FileNotFoundException e){System.out.println("Creat File Error!");System.exit(1);}}public void addRecord(){AccountRecord record = new AccountRecord();System.out.print("enter account number(>0), first name, last name, balance\n? ");Scanner input = new Scanner (System.in);while (input.hasNext()){try{record.setAccount( input.nextInt() );record.setFirstName( input.next() );record.setLastName( input.next() );record.setBalance( input.nextDouble() );if (record.getAccount() < 0){System.out.println("account number must greater than 0, try again");}else{textFile.format("%d %s %s %.2f\n", record.getAccount(), record.getFirstName(),record.getLastName(), record.getBalance() );System.out.print("enter account number(>0), first name, last name, balance\n? ");}}catch (InputMismatchException e){System.out.println("Input invailed,try again");input.nextLine();}}}public void closeFile(){textFile.close();}public static void main (String args[] ){ CreatTextFile myTest = new  CreatTextFile(); myTest.creatFile(); myTest.addRecord(); myTest.closeFile();}}

下面是读取文件

import java.io.File;import java.io.FileNotFoundException;import java.util.Scanner;import java.util.InputMismatchException;public class ReadFiles {public Scanner input;public void openFiles(){try{input = new Scanner ( new File ("D:\\Java\\FIG14.7\\test.txt"));}catch (SecurityException e){System.out.println("You have no access to this file.");System.exit(1);}catch(FileNotFoundException e){System.out.println("File not found.");System.exit(1);  //注意 一定要加 exit语句，否则程序在捕捉后还会运行！！！}/*catch (IllegalStateException e){}*/}public void readData(){AccountRecord record = new AccountRecord();while (input.hasNext() ){try{record.setAccount( input.nextInt() );record.setFirstName( input.next() );record.setLastName( input.next() );record.setBalance( input.nextDouble() );}catch (InputMismatchException e){System.out.println( "inputMismatch");System.exit(1);}System.out.printf("%d\t%s\t%s\t%.2f\n", record.getAccount() , record.getFirstName(), record.getLastName(), record.getBalance() );}}public void closeFile(){input.close();}public static void main(String argc[] ){ReadFiles a= new ReadFiles();a.openFiles();a.readData();a.closeFile();}}