Programming Forums > Application Development > Java

crawforddavid2006 · May 27th, 2006, 1:23 AM

I was wondering exactly what I need to do (import... classes... methods) to read text from an external file. I honestly have no idea where to start so any help is great Thanks

Booooze · May 27th, 2006, 1:27 AM

http://www.programmingforums.org/for...ad.php?t=10008

It was 2 posts down man. If you really have no idea, at least make sure you kow the basics of Java first.

Mjordan2nd · May 27th, 2006, 1:27 AM

Here is an example (uncompiled, so there might be syntactical errors)

(Toggle Plain Text)

import java.io.*;
import java.util.*;

public static void main(String [] args) throws IOException
{
	 Scanner myFile = new Scanner(new File("filename.txt")) // creates a Scanner object to read from file filename.txt
	 /* use the appropriate Scanner methods here to read from your file*/
}

Scanner methods can be found here: http://java.sun.com/j2se/1.5.0/docs/...l/Scanner.html

Toro · May 27th, 2006, 1:27 AM

you would import java.io and javax.swing packages. File is the class that contains information about a file. JFileChooser is a dialog where you can open and save files.

[PHP]
//getting files graphically
JFileChooser chooser = new JFileChooser();
File file;
int result = chooser.showOpenDialog(null);
if( result == JFileChooser.APPROVE_OPTION)
file = chooser.getSelectedFile();
[/PHP]
This is how would you get a File using the "JFileChooser" class, located in the "javax.swing.JFileChooser". "File" is located in "java.io.File"

EDIT: "Core Java 2: Fundamentals, 7th Edition" by Cay Horstman has a great explaination on I/O classes. I recommend you check that out.

titaniumdecoy · May 27th, 2006, 1:30 AM

Here is some example code to get you started. I believe this is the preferred way to read/write files in Java. This code reads the first line from file.in and writes it to file.out.

(Toggle Plain Text)

import java.io.*;

public class IOTest {
  public static void main (String [] args) throws IOException {
    
    RandomAccessFile f = new RandomAccessFile("file.in", "r");
    String firstLine = f.readLine();
    f.close();
    
    PrintWriter out = new PrintWriter(
            new BufferedWriter(
            new FileWriter("file.out")));
    out.println(firstLine);
    out.close();
    
  }
}

Toro · May 27th, 2006, 1:32 AM

YEAH! I forgot to mention that when using I/O classes, most of them throw exceptions like IOExpetion, FileNotFoundException, and etc. A good reference or concept of Exception Handling in Java is a must for using the I/O Classes.

Props at titaniumdecoy for that good reminder, lol.

crawforddavid2006 · May 27th, 2006, 1:35 AM

Quote:

Originally Posted by Booooze

http://www.programmingforums.org/for...ad.php?t=10008

It was 2 posts down man. If you really have no idea, at least make sure you kow the basics of Java first.

I did know it was 2 posts down because that is what sparked my curiosity. I did not want to interupt that thread with my own questions. I have found that to be rude and people don't appreciate it. Thanks for the help

Booooze · May 27th, 2006, 2:31 AM

Quote:

Originally Posted by crawforddavid2006

I did know it was 2 posts down because that is what sparked my curiosity. I did not want to interupt that thread with my own questions. I have found that to be rude and people don't appreciate it. Thanks for the help

Agreed. Don't interupt with your own questions, but it seemed like you had the same question. Owell, you have plenty of resources now

May 27th, 2006, 1:27 AM	#3
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	Here is an example (uncompiled, so there might be syntactical errors) (Toggle Plain Text) import java.io.; import java.util.; public static void main(String [] args) throws IOException { Scanner myFile = new Scanner(new File("filename.txt")) // creates a Scanner object to read from file filename.txt /* use the appropriate Scanner methods here to read from your file/ } import java.io.; import java.util.; public static void main(String [] args) throws IOException { Scanner myFile = new Scanner(new File("filename.txt")) // creates a Scanner object to read from file filename.txt / use the appropriate Scanner methods here to read from your file*/ } Scanner methods can be found here: http://java.sun.com/j2se/1.5.0/docs/...l/Scanner.html __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

May 27th, 2006, 1:30 AM	#5
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 904 Rep Power: 3	Here is some example code to get you started. I believe this is the preferred way to read/write files in Java. This code reads the first line from file.in and writes it to file.out. (Toggle Plain Text) import java.io.; public class IOTest { public static void main (String [] args) throws IOException { RandomAccessFile f = new RandomAccessFile("file.in", "r"); String firstLine = f.readLine(); f.close(); PrintWriter out = new PrintWriter( new BufferedWriter( new FileWriter("file.out"))); out.println(firstLine); out.close(); } } import java.io.; public class IOTest { public static void main (String [] args) throws IOException { RandomAccessFile f = new RandomAccessFile("file.in", "r"); String firstLine = f.readLine(); f.close(); PrintWriter out = new PrintWriter( new BufferedWriter( new FileWriter("file.out"))); out.println(firstLine); out.close(); } }

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May 27th, 2006, 1:27 AM	#2
Booooze Expert Programmer Join Date: Mar 2006 Location: Igloo Posts: 710 Rep Power: 3	http://www.programmingforums.org/for...ad.php?t=10008 It was 2 posts down man. If you really have no idea, at least make sure you kow the basics of Java first.

May 27th, 2006, 1:27 AM	#4
Toro Hobbyist Programmer Join Date: Apr 2006 Posts: 136 Rep Power: 0	you would import java.io and javax.swing packages. File is the class that contains information about a file. JFileChooser is a dialog where you can open and save files. [PHP] //getting files graphically JFileChooser chooser = new JFileChooser(); File file; int result = chooser.showOpenDialog(null); if( result == JFileChooser.APPROVE_OPTION) file = chooser.getSelectedFile(); [/PHP] This is how would you get a File using the "JFileChooser" class, located in the "javax.swing.JFileChooser". "File" is located in "java.io.File" EDIT: "Core Java 2: Fundamentals, 7th Edition" by Cay Horstman has a great explaination on I/O classes. I recommend you check that out.

May 27th, 2006, 1:32 AM	#6
Toro Hobbyist Programmer Join Date: Apr 2006 Posts: 136 Rep Power: 0	YEAH! I forgot to mention that when using I/O classes, most of them throw exceptions like IOExpetion, FileNotFoundException, and etc. A good reference or concept of Exception Handling in Java is a must for using the I/O Classes. Props at titaniumdecoy for that good reminder, lol.

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Programming Forums > Application Development > Java

How do I read a file?