reading a file, then replacing a string...

[Rogelio Tristan]

heres the package (compiles great)
http://www.outrun.org/shiz/skool/Students.java

package MyPack;
import java.io.*;
import java.util.*;
 
public class Students 
 {
  String input;
  String fname;
  String lname;
  int birthM;
  int birthD;
  int birthY;
 

  Calendar bday = new GregorianCalendar();
  int grade = 0;
  String strgrade;
 
  BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
 
 public void GetName() 
 {
 
                
       try
       {
        System.out.print("First name, Moron: ");
        fname = console.readLine();
       }
       catch(IOException ioex)
       {
        System.out.println("Input error!! idiot!!");
        System.exit(1);
       }//end try catch
    
    
       try
       {
        System.out.print("Last name, Moron: ");
        lname = console.readLine();
       }
       catch(IOException ioex)
       {
        System.out.println("Input error!! idiot!!");
        System.exit(1);
       }
        catch(Exception ioErr)
      {
        System.out.println(ioErr);
      }//end try catch
 
 try
  {
  //File f = new File ("./", "text.txt");
  FileWriter fos = new FileWriter("text.txt", true);
  String s = fname + " " + lname + " \n";
  char[] b = new char[s.length()];
  s.getChars(0, s.length(), b, 0);
  fos.write(b);
  fos.close();
  }
 catch(Exception ioErr)
  {
  System.out.println("No file exists...");
  }//end try catch
 }//end public void getname
  
  public void Printname() 
  {
   System.out.println("Name is " + fname + " " + lname + " ok!");
  }
 

  public void Getbdate() 
  {
   try
     {
     System.out.println("Enter birthdate, Moron!");
     System.out.print("Enter number of month(1 - 12) : ");
     input = console.readLine();
     birthM = Integer.parseInt(input);
 
     System.out.print("Enter Day!! : ");
     input = console.readLine();
     birthD = Integer.parseInt(input);
 
     System.out.print("Enter Year... : ");
     input = console.readLine();
     birthY = Integer.parseInt(input);
     }
   catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
 
 
 if(birthM > 12) 
  {
  System.out.println("Max Number of months in a year is 12");
   try
     {
     System.out.println("Enter number of month(1 - 12)");
     input = console.readLine();
     birthM = Integer.parseInt(input);
     }
   catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
   }
   
 if(birthD > 31) 
  {
  System.out.println("Max number of days in a month is 31");
   try
     {
     System.out.println("Enter number of month(1 - 31)");
     input = console.readLine();
     birthD = Integer.parseInt(input);
     }
   catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
   }
 
 if(birthY > 2004) 
  {
  System.out.println("Person isn't born yet");
   try
     {
     System.out.println("Enter Year of birth");
     input = console.readLine();
     birthY = Integer.parseInt(input);
     }
   catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
   }
 
 try
  {
  //File f = new File ("./", "text.txt");
  FileWriter fos = new FileWriter("text.txt", true);
  String s = birthM + "/" + birthD + "/" + birthY + " \n";
  char[] b = new char[s.length()];
  s.getChars(0, s.length(), b, 0);
  fos.write(b);
  fos.close();
  }
 catch(Exception ioErr)
  {
  System.out.println("No file exists...");
  }//end try catch bdate
   
  }//end get b date
 
  public void Printbdate() 
  {
   System.out.println("Birthday is " + birthM + "/" + birthD + "/" + birthY + " ok!");
  }
 
  public void Getgrade() 
  {
 
     try
     {
      System.out.print("Enter Grade, Moron: ");
      strgrade = console.readLine();
      grade = Integer.parseInt(strgrade);
     }
     catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
 

 try
  {
  //File f = new File ("./", "text.txt");
  FileWriter fos = new FileWriter("text.txt", true);
  String s = "Grade " + strgrade + "\n\n";
  char[] b = new char[s.length()];
  s.getChars(0, s.length(), b, 0);
  fos.write(b);
  fos.close();
  }
 catch(Exception ioErr)
  {
  System.out.println("No file exists...");
  }//end try catch getgrade
 

  }//end getgrade
 

  public void Printgrade() 
  {
   System.out.println("Grade is " + grade + " ok!");
  }
 

}

heres the main java file (works and compiles fine)
http://www.outrun.org/shiz/skool/part2.java

//Programmer: Rogelio Trist�n
//Date: 11/12/04
//Program: Student Database project 2!
 
import java.io.*;
import java.util.*;
import MyPack.Students; //package I made
 

public class part2
{
 

 
 public static void main(String[] args)
 {
 Vector v = new Vector(1,1);
 
 BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
 String strans = "";
 int intans = 1;
 Calendar date = new GregorianCalendar();
 Students coolies = new Students(); 
 Students coolies2 = new Students(); 
 int sizevector = 0;
 int current = 0;
 int i = 0;
 String strsearch = "";
 int intsearch = 0;
 String wow = "";
 
 while (intans != 0)
 {
 
 System.out.println("\nCurrent Date");
 System.out.println(date.get(Calendar.MONTH) + "/" + date.get(Calendar.DAY_OF_MONTH) + "/" + date.get(Calendar.YEAR) + "\n");
 System.out.println("Pick an option...");
 System.out.println("1.Enter a new student");
 System.out.println("2.List all students names");
 System.out.println("3.Retrieve a student by an index number");
 System.out.println("4.List all students in detail");
 System.out.println("0.X");
 

     try
     {
      System.out.print("Enter choice: ");
      strans = console.readLine();
      intans = Integer.parseInt(strans);
     }
     catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
 
   System.out.println("\n");
 
  switch (intans)
   {
    case 1:
    sizevector = v.size();
    coolies = new Students(); 
    coolies.GetName();
    coolies.Getbdate();
    coolies.Getgrade();
    System.out.println("\n");
    coolies.Printname();
    coolies.Printbdate();
    coolies.Printgrade();
 
    v.addElement(coolies);
    System.out.println("Your Student number is : " + sizevector + " ok!");
    break;
 
    case 2:
    sizevector = v.size();
    for(int count = 0; count < sizevector; count++)
    {
     System.out.println("\nStudent number " + count);  
     coolies2 =  (Students) v.elementAt(count);
     coolies2.Printname();
    }
    break; 
 
    case 3:
     sizevector = v.size();
         try
     {
      System.out.print("Enter Student number: ");
      strsearch = console.readLine();
      intsearch = Integer.parseInt(strsearch);
     }
     catch(IOException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
     catch(ArrayIndexOutOfBoundsException ioex)
     {
      System.out.println("Input error!! idiot!!");
      System.exit(1);
     }
 

 
      System.out.println("\nStudent number " + intsearch);  
      coolies2 =  (Students) v.elementAt(intsearch);
      coolies2.Printname();
      coolies2.Printbdate();
      coolies2.Printgrade();
 
    break;
 
    case 4:    
  try 
   {
    File f = new File("text.txt");
    FileReader fis = new FileReader(f);
    boolean status = true;
     while(status)
      {
       int m = fis.read();
       
       if ( m != -1)
        {
         System.out.print((char)m);
        }
       else
        {
        status = false;
        }
      }//end while
    fis.close();
   }
  catch(Exception ioErr)
   {
    System.out.println(ioErr);
   }//end try catch
    break;
   }//end case thingy
  }//end while
 }//end main
} 

Okay, its supposed to create a text.txt file, and it does, then with each student enter in a new entry of student in the text file. which it does fine.

It also can display all the contests of the text file, which is does fine.

however I am extremely stuck at how to get it to search the text file for a certain word, and rplace it with another word. I know I'm going to have to throw the entire text file into an instance of a string, but how (syntactically) would I do that? and how would I make it search and replace the text? I think I have to use the pushback somehow.. right?

any help is appreciated, thanks

[Stan James]

If your replacement value is exactly the same length as your find value, you can get real tricky with RandomAccessFile and update it in place. This doesn't often come together unless you have carefully designed fixed length records in your file.

So, much more likely you'll have to read the file, replace the value in memory and rewrite the file. You can read the whole thing into one string and do replacements, or read, replace and write one line at a time. If you're in JDK 1.4 (or want to use a 3rd party jar) you can look at Pattern for regular expressions, otherwise look at String.indexOf() for searching and lots of String.substring() for replacing.

Here's a trick I picked up from an old IBM operating system ...

read original
write temp
rename original to backup
rename temp to original
erase backup

That's a very paranoid and safe way to avoid losing the file through some error.

Holler if you need guidance on the particulars.
[ November 16, 2004: Message edited by: Stan James ]